Dissertations / Theses on the topic 'Tunable single photon source'
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Zhang, Jiaxiang. "Single- and entangled-photon emission from strain tunable quantum dots devices." Doctoral thesis, Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-177579.
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On demand single-photon and entangled-photon sources are key building-blocks for many proposed photonic quantum technologies. For practical device applications, epitaxially grown quantum dots (QDs) are of increasing importance due to their bright photon emission with sharp line width. Particularly, they are solid-state systems and can be easily embedded within a light-emitting diode (LED) to achieve electrically driven sources. Therefore, one would expect a full-fledged optoelectronic quantum network that is running on macroscopically separated, QD-based single- and entangled-photon devices.
An all-electrically operated wavelength-tunable on demand single-photon source (SPS) is demonstrated first. The device consists of a LED in the form of self-assembled InGaAs QDs containing nanomembrane integrated onto a piezoelectric crystal. Triggered single photons are generated via injection of ultra-short electrical pulses into the diode, while their energy can be precisely tuned over a broad range of about 4.8 meV by varying the voltage applied to the piezoelectric crystal. High speed operation of this single-photon emitting diode up to 0.8 GHz is demonstrated.
In the second part of this thesis, a fast strain-tunable entangled-light-emitting diode (ELED) is demonstrated. It has been shown that the fine structure splitting of the exciton can be effectively overcome by employing a specific anisotropic strain field. By injecting ultra-fast electrical pulses to the diode, electrically triggered entangled-photon emission with high degree of entanglement is successfully realized. A statistical investigation reveals that more than 30% of the QDs in the strain-tunable quantum LED emit polarization-entangled photon-pairs with entanglement-fidelities up to f+ = 0.83(5). Driven at the highest operation speed ever reported so far (400 MHz), the strain-tunable quantum LED emerges as unique devices for high-data rate entangled-photon applications.
In the end of this thesis, on demand and wavelength-tunable LH single-photon emission from strain engineered GaAs QDs is demonstrated. Fourier-transform spectroscopy is performed, from which the coherence time of the LH single-photon emission is studied. It is envisioned that this new type of LH exciton-based SPS can be applied to realize an all-semiconductor based quantum interface in the foreseeable distributed quantum networks.
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Jamil, Ayesha. "Growth of site-controlled InAs quantum dots with tunable emission for future single photon sources." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.607798.
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Finazzer, Matteo. "Boîtes quantiques accordées par contrainte mécanique et nanostructures photoniqueslarge bande pour le traitement quantique de l'information." Electronic Thesis or Diss., Université Grenoble Alpes, 2024. http://www.theses.fr/2024GRALY014.
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Les sources de photons uniques indiscernables accordables en longueur d’onde sont des composants clés pour les technologies quantiques de l'information. La réalisation d'un tel dispositif avec une boîte quantique semi-conductrice (BQ) nécessite un "bouton" pour accorder la longueur d'onde de l’émetteur et une structure photonique offrant une grande efficacité d'extraction de la lumière sur une large bande passante. Cette thèse présente plusieurs étapes importantes vers cet objectif.Nous étudions tout d'abord une cavité nanonocylindre, structure photonique qui, bien que très simple, offre une forte accélération de l'émission spontanée par effet Purcell sur une large bande passante. Pour la première fois, nous réalisons une spectroscopie strictement résonante d'une BQ intégrée dans une telle structure, en exploitant une détection avec une polarisation croisée pour supprimer la lumière parasite associée au laser d’excitation (collaboration avec le groupe de Richard Warburton). Ceci a permis une caractérisation fine des propriétés optiques de l'émetteur.Nous démontrons ensuite une source de photons uniques accordable basée sur une BQ intégrée dans une antenne à fil photonique. Des électrodes intégrées appliquent une force électrostatique qui tord le fil ; la déformation mécanique qui en résulte modifie l'énergie de bande interdite des BQs. Nous contrôlons la direction de flexion du fil et démontrons le décalage, vers les grandes comme vers les courtes longueurs d’ondes, de l'émission des BQs.En utilisant une tension alternative, l'actuation électrostatique peut également exciter les modes de vibration du nanofil. Cette capacité est intéressante dans le contexte de la nanomécanique hybride. Dans ces expériences, nous tirons parti de la photoluminescence des BQs pour détecter et identifier les modes de vibration mécaniques. En particulier, nous mettons en évidence un mode de flexion d'ordre élevé qui résonne à 190 MHz, une valeur qui dépasse le taux d’émission spontanée de la BQ. Ceci constitue une étape importante vers l’obtention du régime de bandes latérales résolues pour ce système.Les dispositifs étudiés dans ce travail ouvrent des perspectives très prometteuses pour les développements futurs de la photonique quantique et de la nanomécanique hybrideBright and tunable sources of indistinguishable single photons are key devices for photonic quantum information technologies. Building such a source with a semiconductor quantum dot (QD) requires a “knob” to tune the QD emission wavelength combined with a broadband photonic structure for light extraction. This thesis reports several important steps towards this goal.We first investigate a nanocylinder cavity, a photonic structure that, despites its simplicity, offers a pronounced Purcell acceleration of spontaneous emission over a large spectral bandwidth. We demonstrate the first resonant optical spectroscopy of a QD embedded in a nanopost cavity, by leveraging a cross-polarization scheme that efficiently suppresses stray laser light (collaboration with the group of Richard Warburton). This technique enabled a precise characterization of the optical properties of the emitter.We next demonstrate a tunable single-photon source based on a QD embedded in a tapered photonic wire. In our device, a set of on chip electrodes biased with a DC voltage applies an electrostatic force to the wire. As the wire bends, the resulting mechanical strain changes the bandgap energy of the embedded QDs. We demonstrate both a large increase and a large decrease of the QD emission wavelength by controlling the wire bending direction.With an AC voltage, the above-mentioned actuation scheme can also excite the vibration modes of the nanowire. This capability is interesting in the context of hybrid nanomechanics. In our experiments, we leverage the QD photoluminescence to detect and identify the wire mechanical vibrations. In particular, we evidence a high-order flexural mode that resonates at 190 MHz, a value that exceeds the QD radiative rate. This constitutes an important step towards the spectrally-resolved-sidebands regime.The devices demonstrated in this work open promising prospects for the future developments of quantum photonics and hybrid nanomechanics
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Riley-Watson, Andrew G. "A fibre-based single-photon source." Thesis, University of Sussex, 2013. http://sro.sussex.ac.uk/id/eprint/45315/.
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The controlled emission and absorption of single photons is an important enabling technology in the fields of quantum communication, cryptography and computing. We have realised a novel single photon source, based on a miniature ‘endcap' ion trap with integrated optical fibres. To minimise distortion of the trapping field the fibres are tightly integrated and recessed within the two hollow cylindrical rf electrodes of the trap. This allows us to bring the fibres to within approximately 300 μm of the trapped ion. With the fibres in place we are able to collect the ion's fluorescence using no further optics. In this thesis the ion trap is fully characterised, and the quantum nature of the light demonstrated in the results of a variant on the Hanbury Brown-Twiss photon-correlation experiment. The scheme will ultimately be extended to implement a coherent ion-photon interface through strong coupling cavity-QED. Towards this end, an ultra-high-finesse cavity has been designed and fabricated by laser-machining and coating surfaces with a range of radii of curvature on the end facets of the fibres. To improve the stability and precision manipulation of the cavity in-vacuum, an entirely new trap has been designed and built. Finally, the current status of the fibre cavity and the outlook for the experiment are presented.
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Dilley, Jerome Alexander Martin. "A single-photon source for quantum networking." Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:380a4aaf-e809-4fff-84c7-5b6a0856a6cf.
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Cavity quantum electrodynamics (cavity QED) with single atoms and single photons provides a promising route toward scalable quantum information processing (QIP) and computing. A strongly coupled atom-cavity system should act as a universal quantum interface, allowing the generation and storage of quantum information. This thesis describes the realisation of an atom-cavity system used for the production and manipulation of single photons. These photons are shown to exhibit strong sub-Poissonian statistics and indistinguishability, both prerequisites for their use in realistic quantum systems. Further, the ability to control the temporal shape and internal phase of the photons, as they are generated in the cavity, is demonstrated. This high degree of control presents a novel mechanism enabling the creation of arbitrary photonic quantum bits.
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Intallura, Philip Michael. "Quantum communication with a single photon source." Thesis, University of Cambridge, 2010. https://www.repository.cam.ac.uk/handle/1810/283859.
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Dalgarno, Paul Allan. "Time correlated single photon counting on charge tunable semiconductor quantum dots." Thesis, Heriot-Watt University, 2005. http://hdl.handle.net/10399/202.
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Sadler, Thomas Christopher. "Nitride distributed Bragg reflectors for single photon source applications." Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608521.
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Leone, Nicolò. "A quantum entropy source based on Single Photon Entanglement." Doctoral thesis, Università degli studi di Trento, 2022. https://hdl.handle.net/11572/339572.
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In this thesis, I report on how to use Single Photon Entanglement for generating certified quantum random numbers. Single Photon Entanglement is a particular type of entanglement which involves non-contextual correlations between two degrees of freedom of a single photon. In particular, here I consider momentum and polarization. The presence of the entanglement was validated using different attenuated coherent and incoherent sources of light by evaluating the Bell inequality, a well-known entanglement witness. Different non-idealities in the calculation of the inequality are discussed addressing them both theoretically and experimentally. Then, I discuss how to use the Single Photon Entanglement for generating certified quantum random numbers using a semi-device independent protocol. The protocol is based on a partial characterization of the experimental setup and the violation of the Bell's inequality. An analysis of the non-idealities of the devices employed in the experimental setup is also presented
In the last part of the thesis, the integrated photonic version of the previously introduced experiments is discussed: first, it is presented how to generate single photon entangled states exploiting different degrees of freedom with respect to the bulk experiment. Second, I discuss how to perform an integrated test of the Bell's inequality.
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Gorniaczyk, Hannes M. [Verfasser]. "Single Photon Transistor mediated by electrically tunable Rydberg-Rydberg Interactions / Hannes M. Gorniaczyk." München : Verlag Dr. Hut, 2017. http://d-nb.info/1126297313/34.
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Conterio, Michael John. "An electrically driven resonant tunnelling semiconductor quantum dot single photon source." Thesis, University of Cambridge, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708597.
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Beltran, Madrigal Josslyn. "Integration of a single photon source on a planar dielectric waveguide." Thesis, Troyes, 2017. http://www.theses.fr/2017TROY0007/document.
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Le développement de dispositifs optiques intégrés dans des domaines tels que l'information quantique et la détection de molécules est actuellement dirigé vers l'intégration de nanosources (NS) sur des systèmes sur puce avec faible pertes de propagation. Cette thèse montre une contribution à la conception, à la fabrication et à la caractérisation de structures photonique-plasmoniques en vue de l'intégration d'une seule NS sur des puces optiques à travers le spectre visible. Nous recherchons à optimiser l’efficacité d’excitation et de collection de l'émission de la fluorescence d'une NS en combinant un nano-prisme en or et une structure formée par une couche de dioxyde de titane (TiO2) et un guide d'ondes à échange d'ions (IEW) sur verre. Le couplage entre les modes permet un transfert efficace de l'énergie entre un mode faiblement confiné dans l'IEW vers un mode plasmonique confiné dans un volume effectif de quelques nanomètres cubes. Ce mode confiné interagit avec une NS en améliorant son émission de fluorescence par l'effet de facteur Purcell. En utilisant le théorème de réciprocité de l'électromagnétisme, nous avons étudié le cas réciproque où la lumière émise par la NS peut être collectée dans les modes photoniques du IEW.La caractérisation a été réalisée en champ lointain et en champ proche avec en particulier l'utilisation d'un microscope optique de champ proche à sonde diffusante (SNOM). Nous avons proposé une configuration SNOM qui permet d'imiter l'interaction d'une NS et des systèmes guidés, cartographiant la densité locale des modes guidés (LDOM)The development of integrated optical devices in areas such as quantum information and molecular sensing is currently directed towards the integration of nanosources (NS) into systems on a chip with low propagation losses. This thesis shows a contribution on the design, fabrication, and characterization of photonic-plasmonic structures towards the integration of a NS on optical chips across the visible spectrum. We pursue the efficient excitation and collection of the fluorescence emission of a NS by making use of the interaction between an electromagnetic field concentrator (gold nanoprism) and an integrated optics structure formed by a high-index layer of titanium dioxide (TiO2) and a low-contrast index ion exchanged waveguide on glass (IEW). The coupling mode allows an efficient transfer of the energy between a weakly confined mode in the IEW and a plasmonic mode confined in an effective volume of few cubic nanometers. This confined mode interacts with a NS enhancing its florescence emission through Purcell factor effect. Using the reciprocity theorem of electromagnetism, we studied the reciprocal case where the light emitted by the NS can be collected into the photonic modes of the IEW.The characterization was performed in the far and in the near field with the use of a scanning near-field optical microscopy (SNOM). We proposed a SNOM configuration that allows us to imitate the interaction of a NS and guided systems, mapping the local density of guided modes (LDOM)
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Klarup, Kyle. "Density Controlled Photon Pair Generation: a Prototype Source of Tunable Entangled Photons from Supercritical Xenon." Thesis, University of Oregon, 2018. http://hdl.handle.net/1794/23127.
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This dissertation describes the development and verification of a fiber based prototype system for generating entangled photon pairs with a reduced spontaneous Raman scattering background compared to solid-core optical fibers. To achieve this goal, the guidance properties of hollow-core photonic bandgap fibers are combined with the density variability and high optical nonlinearity of supercritical xenon fluid. The dispersion properties of the system provide the proper conditions for the spontaneous generation of entangled photons by the nonlinear process of degenerate four-wave mixing. By altering the density of supercritical xenon in the fiber, the conditions for the four-wave mixing can be modified to tune the frequencies of the entangled photons.
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Zhang, Xiang. "Single and entangled photon manipulation for photonic quantum technologies." Thesis, The University of Sydney, 2018. http://hdl.handle.net/2123/19899.
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Photonic quantum technologies that harness the fundamental laws of quantum physics open the possibility of developing quantum computing and communication that could show unprecedented computational power on specific problems and unconditional information security, respectively. However, the lack of high-efficiency single-photon sources and integrated photonic circuits that can generate, manipulate and analyse entanglement states are the major hurdles to demonstrate the quantum advantages. The potential solutions are clearly explained in this thesis. Chapter 1 provides a brief overview that explains the theme of each chapter. Chapter 2 emphasises the importance of a high-efficiency single-photon source and an integrated time-bin entanglement chip, after explaining the advantages of photonic quantum computing and communication over their classical counterparts. In Chapter 3, three different temporal multiplexing schemes are experimentally demonstrated as the potential solutions to build a high-efficiency single-photon source. Chapter 3 also identifies the potential limitations of temporal multiplexing with high repetition rate. In Chapter 4, the linear processing circuits and nonlinear photon source are separately demonstrated in a low-loss double-stripe silicon nitride waveguide. In the final section of Chapter 4, an integrated silicon nitride time-bin entanglement chip that combines linear processing circuits and nonlinear photon sources is demonstrated as a potential solution to build a robust, scalable and cost-efficient quantum network in the real world. After a succinct summarisation, the final chapter briefly discusses the promising strategies and platforms to build an integrated high-efficiency single-photon source and an integrated quantum node with broad bandwidth and long storage time.
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Wang, Chunlang. "A Solid-State Single Photon Source Based on Color Centers in Diamond." Diss., lmu, 2007. http://nbn-resolving.de/urn:nbn:de:bvb:19-72761.
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Vezzoli, S. "EXPERIMENTAL STUDY OF NANOCRYSTALS AS SINGLE PHOTON SOURCES." Doctoral thesis, Università degli Studi di Milano, 2013. http://hdl.handle.net/2434/222688.
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Wet-chemically synthesized colloidal nanocrystals are promising single photon emitters at room temperature, due to the strong quantum confinement induced by the small dimensions. However, their applications have been so far limited by two main drawbacks: the blinking of their photo-luminescence and a non-polarized emission.
This manuscript is consecrated to the study of the optical properties of a particular type of colloidal nanocrystals, called dot-in-rod (DR), in which a spherical CdSe core is surrounded by a rod-like CdS shell.
We demonstrate for the first time a suppression of the blinking in thick shell DRs. In contrast to spherical nanocrystals, we show that it can be obtained while keeping a good quality of the single photon emission and a high degree of linear polarization.
A complete room-temperature characterization of the optical, and especially quantum optical, properties of DRs is provided for several geometrical parameters.
In particular, an original approach, based on an ensemble photoluminescence measurement, is developed to assess the quality of a sample of nanocrystals as single photon sources.
By studying single DRs in a confocal microscope, we analyze the influence of the core size and of the shell thickness and length on the photon anti-bunching, radiative lifetime and polarization of the emission.
This systematic study brings a contribution to the understanding of the interaction processes of the confined carriers in semiconductor nanocrystals. The interplay of radiative and non-radiative recombinations and, in particular, the role of the Auger effect in the photo-luminescence blinking and in the emission of non-classical light are deeply investigated.
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Ripka, Fabian [Verfasser]. "A Single-Photon Source Based on Strongly Interacting Thermal Rydberg Atoms / Fabian Ripka." München : Verlag Dr. Hut, 2019. http://d-nb.info/1194288855/34.
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Finch, Jeffrey William. "Selective mass spectrometry by single-photon ionization from a molecular hydrogen laser source." Diss., The University of Arizona, 1992. http://hdl.handle.net/10150/185895.
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A molecular hydrogen laser, with an output of 7.8 eV photons in the vacuum ultraviolet, is evaluated as a selective source for photoionization mass spectrometry. Types of compounds ionized by the laser include a variety of amines, nitrogen heterocycles, drugs of abuse, pharmaceuticals, and polynuclear aromatic hydrocarbons (PAHS). The laser is coupled to a time-of-flight mass analyzer, which allows a spectrum to be recorded with each laser pulse. The laser is a "soft" ionization source and mass spectra of nearly all of the compounds studied yield single ion peaks due to the parent molecule with no fragments. This results in simplified mass spectra with a one-to-one correspondence of photoactive molecules with molecular ion peaks. Since the photoionization threshold of the laser is relatively low, selectivity of the photoactive species is high in the presence of a complex sample matrix. The performance of the laser source is improved with a few changes in the original design. In addition, the previous method of recording mass spectra with a photographic emulsion is replaced with a digital oscilloscope, which averages spectra over many laser pulses. As a result, a true assessment of the technique's sensitivity is finally achieved. The time-of-flight mass spectrometer is modified with a new microchannel plate ion detector and preamplifier. As a result, detection limits for PAH's improve by nearly three orders of magnitude, from the 100 ng range to the 100 pg range. Selectivity of the laser photoionization source in complex mixture analysis is demonstrated with the ability to detect PAH's in a drinking water sample at concentrations below 100 parts-per-trillion, using a simple solid-phase extraction technique. Application of the technique for rapid screening of drugs of abuse in urine is demonstrated where solid-phase extraction columns are utilized for sample pretreatment. Urine samples spiked with drugs such as cocaine, codeine, morphine, phencyclidine, and methadone, yield photoionization mass spectra consisting of parent molecular ions for the drugs with a few noninterfering ion signals from the matrix. The technique is evaluated and compared to other drug screening techniques such as enzyme-multiplied immunoassay.
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McMillan, Alex. "Development of an all-fibre source of heralded single photons." Thesis, University of Bath, 2012. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.557827.
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The preparation of single photons in a pure quantum state is a subject of great interest in physics, enabling the control of light at an unprecedented level. The ease with which certain degrees of freedom of photon states, such as polarisation, can be manipulated, along with the inherent resilience of photons to decoherence, makes them well suited for use as qubits. Recent rapid developments in the transmission and processing of quantum information, as well as the likely technological impact of potential real-world applications such as quantum cryptography and quantum computation, mean that the demand for high performance single photon sources is likely to increase in the near future. One approach to producing single photon states, which are known to be in a well-defined spatio-temporal mode without destructively measuring them, is to take advantage of nonlinear optics. Nonlinear processes can be used to realise frequency conversion by generating a single, correlated pair of photons from an intense pump laser source. The detection of one of the photons from a pair can then be used to indicate the presence of the other photon in the pair, a procedure known as heralding. This thesis describes the development of a source of heralded single photons at 1550 nm, generated directly in the core of a photonic crystal fibre (PCF). By taking advantage of low loss fibre components for the required spectral filtering of the generated photon state, a heralding fidelity of 52% was achieved. The source was designed to be used with a picosecond pulsed fibre laser, making it relatively low cost and maintenance free. With 148 mW of average pump power a heralded output photon rate of 6.4 × 104 s-1 was observed, demonstrating the brightness of the source. The purity of the generated single photons was established by measuring non-classical interference, with a visibility of 70%, between the photons output from this source and a source based on a PPLN waveguide. The fabrication of a series of birefringent PCFs for the generation of spectrally pure state photons at 1550 nm is also discussed. These PCFs will be useful for incorporation in the next generation of high performance, fibre-based photon sources.
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Spring, Justin Benjamin. "Single photon generation and quantum computing with integrated photonics." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:b08937c7-ec87-47f8-b5ac-902673f87ce2.
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Photonics has consistently played an important role in the investigation of quantum-enhanced technologies and the corresponding study of fundamental quantum phenomena. The majority of these experiments have relied on the free space propagation of light between bulk optical components. This relatively simple and flexible approach often provides the fastest route to small proof-of-principle demonstrations. Unfortunately, such experiments occupy significant space, are not inherently phase stable, and can exhibit significant scattering loss which severely limits their use. Integrated photonics offers a scalable route to building larger quantum states of light by surmounting these barriers. In the first half of this thesis, we describe the operation of on-chip heralded sources of single photons. Loss plays a critical role in determining whether many quantum technologies have any hope of outperforming their classical analogues. Minimizing loss leads us to choose Spontaneous Four-Wave Mixing (SFWM) in a silica waveguide for our source design; silica exhibits extremely low scattering loss and emission can be efficiently coupled to the silica chips and fibers that are widely used in quantum optics experiments. We show there is a straightforward route to maximizing heralded photon purity by minimizing the spectral correlations between emitted photon pairs. Fabrication of identical sources on a large scale is demonstrated by a series of high-visibility interference experiments. This architecture offers a promising route to the construction of nonclassical states of higher photon number by operating many on-chip SFWM sources in parallel. In the second half, we detail one of the first proof-of-principle demonstrations of a new intermediate model of quantum computation called boson sampling. While likely less powerful than a universal quantum computer, boson sampling machines appear significantly easier to build and may allow the first convincing demonstration of a quantum-enhanced computation in the not-distant future. Boson sampling requires a large interferometric network which are challenging to build with bulk optics, we therefore perform our experiment on-chip. We model the effect of loss on our postselected experiment and implement a circuit characterization technique that accounts for this loss. Experimental imperfections, including higher-order emission from our photon pair sources and photon distinguishability, are modeled and found to explain the sampling error observed in our experiment.
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TOLIOPOULOS, DIMOSTHENIS. "Single photon sources integrated on Ge Mie resonator fabricated by solid state dewetting." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2021. http://hdl.handle.net/10281/311361.
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-The following Ph.D. thesis summarizes the work that has been made aiming at the fabrication and characterization of quantum emitters integrated inside Ge nanoisland on Si substrates. We choose to induce localized Ge impurities centers inside a thin layer of Al0.25Ga0.75As epitaxially grown on Ge islands acting as dielectric Mie Resonators (MR’s). These centers are working as light sources, capable of single photon emission and quantum entanglement properties. Fabrication of the Ge islands was done by solid state dewetting in an ultra-high vacuum environment, obtaining both amorphous and monocrystalline islands, with sizes ranging from 50 to 500 nm. These islands are also photonic Mie-resonators enhancing light-matter interaction and steering the localized defects emission, acting as dielectric nanoantennas. This thesis exploits molecular beam epitaxy, solid state dewetting and electron assisted lithography for realizing patterned samples. Many different characterization methods have been used to assess the quality of the fabricated samples. We use morphological characterization via scanning electron microscopy (SEM) and atomic force microscopy (AFM). Optically, we characterized the Mie resonators by dark field (DF) spectroscopy to ensure their photonic mode appearance. Also, the crystallinity of the Ge seeds was investigated by RAMAN spectroscopy. In the end, the optical response of the samples will be tested by micro and macro Photoluminescence, time-resolved measurements, and auto-correlation measurements to assess the quantum nature of the emission at low temperatures. Towards our goal we faced three main different topics: i) the growth of Ge nanoisland via solid state dewetting, ii) the optimization of the photonic response of semiconductor Mie resonators by engineering the geometry of the substrates, iii) the integration of III-V layers on Ge islands and the observation of interesting associated defects. Each of these aspects is described in detail in chapters 3,4 and 5. During my secondments at UNIFI, I had also been involved in a quite different approach towards the deterministic realization of quantum emitters integrated beneath a glass nanoantenna, an activity which led to article submission, but it is not reported in this thesis.
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Schröder, Tim. "Integrated photonic systems for single photon generation and quantum applications." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2013. http://dx.doi.org/10.18452/16723.
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Im Rahmen der vorliegenden Dissertation wurden neuartige integrierte Einzelphotonenquellen (EPQ) und ihre Anwendung für die Quanteninformationsverarbeitung entwickelt und untersucht. Die Erzeugung von Einzelphotonen basiert auf einzelnen Defektzentren in nanometergroßen Diamantkristallen mit einzigartigen optischen Eigenschaften: Stabilität bei Zimmertemperatur ohne optisches Blinken. Diamantkristalle mit Größen bis unter 20nm wurden mit neuartigen „pick-and-place“ Techniken (z.B. mit einem Atomkraftmikroskop) in komplexe photonische Strukturen integriert. Zwei unterschiedliche Ansätze für die Realisierung der neuartigen EPQ wurden verfolgt. Beim ersten werden fluoreszierende Diamantkristalle in nano- und mikrometergroße Faser-basierte oder resonante Strukturen in einem „bottom-up“ Ansatz integriert, dadurch werden zusätzliche optische Komponenten überflüssig und das Gesamtsystem ultra-stabil und wartungsfrei. Der zweite Ansatz beruht auf einem Festkörperimmersionsmikroskop (FIM). Seine Festkörperimmersionslinse wirkt wie eine dielektrische Antenne für die Emission der Defektzentren. Es ermöglicht die höchsten bisher erreichten Photonenzählraten von Stickstoff-Fehlstellen von bis zu 2.4Mcts/s und Einsammeleffizienzen von bis zu 4.2%. Durch Anwendung des FIM bei cryogenen Temperaturen wurden neuartige Anwendungen und fundamentale Untersuchungen möglich, weil Photonenraten signifikant erhöht wurden. Die Bestimmung der spektralen Diffusionszeit eines einzelnen Defektzentrums (2.2µs) gab neue Erkenntnisse über die Ursachen von spektraler Diffusion. Spektrale Diffusion ist eine limitierende Eigenschaft für die Realisierung von Quanteninformationsanwendungen. Das Tisch-basierte FIM wurde außerdem als kompakte mobile EPQ mit Ausmaßen von nur 7x19x23cm^3 realisiert. Es wurde für ein Quantenkryptographie-Experiment implementiert, zum ersten Mal mit Siliziumdefektzentren. Des Weiteren wurde ein neues Konzept für die Erzeugung von infraroten EPQ entwickelt und realisiert.The presented thesis covers the development and investigation of novel integrated single photon (SP) sources and their application for quantum information schemes. SP generation was based on single defect centers in diamond nanocrystals. Such defect centers offer unique optical properties as they are room temperature stable, non-blinking, and do not photo-bleach over time. The fluorescent nanocrystals are mechanically stable, their size down to 20nm enabled the development of novel nano-manipulation pick-and-place techniques, e.g., with an atomic force microscope, for integration into photonic structures. Two different approaches were pursued to realize novel SP sources. First, fluorescent diamond nanocrystals were integrated into nano- and micrometer scaled fiber devices and resonators, making them ultra-stable and maintenance free. Secondly, a solid immersion microscope (SIM) was developed. Its solid immersion lens acts as a dielectric antenna for the emission of defect centers, enabling the highest photon rates of up to 2.4Mcts/s and collection efficiencies of up to 4.2% from nitrogen vacancy defect centers achieved to date. Implementation of the SIM at cryogenic temperatures enabled novel applications and fundamental investigations due to increased photon rates. The determination of the spectral diffusion time of a single nitrogen vacancy defect center (2.2µs) gave new insights about the mechanisms causing spectral diffusion. Spectral diffusion is a limiting property for quantum information applications. The table-top SIM was integrated into a compact mobile SP system with dimension of only 7x19x23cm^3 while still maintaining record-high stable SP rates. This makes it interesting for various SP applications. First, a quantum key distribution scheme based on the BB84 protocol was implemented, for the first time also with silicon vacancy defect centers. Secondly, a conceptually novel scheme for the generation of infrared SPs was introduced and realized.
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Hsiao, Tzu-Kan. "A single-photon source based on a lateral n-i-p junction driven by a surface acoustic wave." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/283189.
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Single-photon sources are essential building blocks in quantum photonic networks, where quantum-mechanical properties of photons are utilised to achieve quantum technologies such as quantum cryptography and quantum computing. In this thesis, a single-photon source driven by a surface acoustic wave (SAW) is developed and characterised. This single-photon source is based on a SAW-driven lateral n-i-p junction in a GaAs quantum-well structure. On this device, the lateral n-i-p junction is formed by gate-induced electrons and holes in two adjacent regions. The SAW potential minima create dynamic quantum dots in a 1D channel between these two regions, and are able to transport single electrons to the region of holes along the channel. Single-photon emission can therefore be generated as these electrons consecutively recombine with holes. After characterisation and optimisation in four batches of devices, clear SAW-driven charge transport and the corresponding electroluminescence (EL) can be observed on an optimised SAW-driven n-i-p junction. Time-resolved measurements have been carried out to study the dynamics of SAW-driven electrons. Time-resolved EL signals indicate that a packet of electrons is transported to the region of holes in each SAW minimum. In addition, the carrier lifetime of SAW-driven electrons in the region of holes is shown to be $\sim 100$ ps, which is much shorter than the SAW period of $860$ ps. Hence, it is promising to observe single-photon emission in the optimised device. In order to test single-photon emission, a Hanbury Brown-Twiss experimental setup has been employed to record an autocorrelation histogram of the SAW-driven EL signal at the single-electron regime. Suppression of autocorrelation coincidences at time delay $\Delta t = 0$ is evidence of photon antibunching. By fitting theoretical functions describing the SAW-driven EL signal, it is found that the second-order correlation function shows $g^{(2)}(0) = 0.39 \pm 0.05$, which is lower than the common criterion for a single-photon source $g^{(2)}(0) < 0.5$. Moreover, theoretical calculation and simulation suggest that, if a constant background signal can be filtered out, $\sim 80 \%$ of the SAW-driven EL is single-photon emission.
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Mosley, Peter James. "Generation of heralded single photons in pure quantum states." Thesis, University of Oxford, 2007. http://ora.ox.ac.uk/objects/uuid:44c36e1e-11ee-41e2-ba29-611c932ce4ff.
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Single photons - discrete wavepackets of light - are one of the most fundamental entities in physics. In recent years, the ability to consistently create and manipulate both single photons and pairs of photons has facilitated everything from tests of quantum theory to the implementation of quantum-enhanced precision measurements. These activities all fall within the scope of the rapidly-growing field of quantum information - the exploitation of the properties of quantum states (and specifically their capability to exist in superpositions) to accomplish tasks that would not be possible with classical objects. One stated goal of research in quantum information is to build a device consisting of a network of quantum logic gates that can evaluate quantum algorithms. The photonic implementation of individual logic gates has already been demonstrated. However, partly due to standard methods of preparing single photons, current schemes have severe limitations in terms of scaling up from a single logic gate to multiple concatenated operations. Until now it has not been proven that single photons can be generated in pure and indistinguishable quantum states, something upon which the successful operation of optical quantum logic gates relies. This thesis presents an experimental demonstration of simultaneous generation of almost identical single photons in highly pure states from two independent sources based on parametric downconversion. This is a process of photon pair generation during the passage of a light beam through a nonlinear crystal; one photon from the resulting pair is detected to herald the other. The work herein describes, refines, and implements a technique that minimises the strong quantum correlations usually present within each pair by spectral engineering of the source. This allows the heralded single photons to be in pure states, a property that is confirmed by observing a high-visibility two-photon interference effect without spectral filtering.
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Ngo, Gia Long. "Manipulation of solid-state single-photon emitters by deterministic coupling into polymer-based photonic structures." Electronic Thesis or Diss., université Paris-Saclay, 2023. http://www.theses.fr/2023UPAST177.
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Dans cette thèse, nous nous concentrons sur l'utilisation de écriture directe par laser par absorption ultra-faible à un-photon (LOPA-DLW) pour coupler précisément des émetteurs de photons uniques à base de nanocristaux colloïdaux (NCx) individuels à des structures polymères multidimensionnelles. Les travaux comportent quatre parties :La première partie présente les propriétés optiques des NCx à cœur/coquille de CdSe/CdS. Nous optimisons l'émission de photons uniques et étudions l'orientation des dipôles d'émission des NC. Nous montrons que les nanocristaux à notre disposition sont des candidats appropriés pour l'intégration à des structures photoniques.La deuxième partie détaille le mécanisme d'écriture par laser utilisé pour coupler les nanocristaux à des structures photoniques arbitraires élaborées à partir de la résine photo négative SU-8. Nous montrons qu'un guide d'ondes circulaire résonant permet d'ajuster le diagramme de rayonnement en champ lointain d'un NC individuel. Nos résultats contribuent à la compréhension des propriétés optiques des structures à base de réseau circulaire concentrique utilisant des matériaux à faible indice de réfraction.La troisième partie présente la réalisation de diviseurs et combineurs optiques utilisant des structures polymères à base de micropiliers verticaux fonctionnant en régime de comptage de photons. Plusieurs architectures sont présentées. Les résultats constituent une avancée vers de futures interconnexions optiques basées sur le couplage d'onde évanescente en configuration verticale.La quatrième partie explore les diviseurs optiques basés sur une structure de guide d'onde polymère en arcs croisés à trois dimensions. Cette approche offre des avantages car la structure est mécaniquement plus stable que les structures à base de micropilliers verticaux et présente des perspectives prometteuses de mise à l'échelle.En conclusion, cette thèse fournit un cadre cohérent pour coupler de manière déterministe des NCx individuels dans des structures photoniques polymères en utilisant la technique d'écriture par laser LOPA-DLW, faisant progresser le domaine de la photonique quantique intégrée. Les travaux futurs pourraient se concentrer sur l'optimisation des structures pour une efficacité accrue et la mise à l'échelle des guides d'onde 3D pour des configurations plus complexesIn this thesis, we focus on utilizing low-one photon absorption (LOPA) direct laser writing (DLW) to precisely couple colloidal quantum dot (QD)-based single photon emitters (SPEs) into multidimensional polymeric structures. The research is segmented into four parts :The first part presents the optical properties of CdSe/CdS core/shell nanocrystals. We optimize single-photon emission and study the orientation of emitting dipoles within the QDs. We identify our QDs as suitable candidates for integration into photonic structures.The second part details the mechanism of LOPA-based DLW to couple QDs into arbitrary photonic structures based on SU-8 negative photoresist. Next, a particular focus on the circular waveguide resonant grating structure allows us to customize far-field radiation patterns of QD-based SPEs. The findings here contribute to the understanding of optical properties of concentric circular grating structures using low refractive index polymer materials.The third part showcases an approach to optical splitters and combiners using vertical polymeric submicropillar structures operating at the single-photon level. Several architectural configurations are introduced. The results represent advancement toward future quantum optical interconnects based on evanescent wave coupling in vertical configuration.The fourth part explores quantum optical splitters based on a 3D polymeric crossed-arc waveguide structure. This approach provides advantages as it is more mechanically stable than submicropillar structures and has potential for scalability.In conclusion, this thesis provides a framework for deterministically coupling single QDs into polymeric photonic structures using LOPA-based DLW, advancing the field of integrated quantum photonics. Future work could focus on optimizing structures for improved efficiency and scaling the 3D waveguides for more complex configurations
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Au, Thi Huong. "Optimisation et manipulation d'une source de photons uniques par des structures photoniques 2D et 3D à base de matériau polymère à température ambiante." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLN046.
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Cette thèse a été consacrée à l'étude théorique et expérimentale du couplage contrôlé de la source de photon unique (SPS) aux structures photoniques multidimensionnelles, par l'utilisation de la méthode dite écriture directe par laser (DLW) par absorption ultra-faible à un photon (LOPA). La thèse est constitutée de trois parties principales suivantes:La première partie concerne le caractérisation et l'optimisation des dots quantiques (QD) colloïdaux CdSe/CdS. La dépendance de la longeur d'onde d'excitation a été étudiée. En utilisant une excitation à 532 nm, seul le core est excité et l’effet d'Auger est donc supprimé. Cette approche permet donc d'obtenir avec la suppression de la commutation intermittente et une source de photon unique très stable à température ambiante. Afin d’obtenir une meilleure performance des QDs sur une longue période, nous avons ensuite étudié l'influence du milieu dans lequel les QDs sont logés sur leurs propriétés optiques. En intégrant les QDs dans les matrices de polymère SU-8, nous avons montré que l'environnement polymérique permet non seulement de conserver de bonnes caractéristiques des QDs CdSe/CdS avec une photostabilité élevée, mais également de nous offrir une excellente accessibilité à la fabrication des structures en polymère contenant une particule unique.Dans la deuxième partie, la technique LOPA DLW est utilisée pour le couplage des QDs uniques dans diverses structures photoniques. Deux dispositifs, l’antenne du type ''pilier diélectrique'' sous-lambda et la membrane de réseau circulaire (cavité du type ''bulleye''), ont été étudiés théoriquement et expérimentalement pour améliorer l’émission du QD couplé en termes de l'émission spatiale et de l’émission radiative spontanée de l’émetteur.Dans la troisième partie, la manipulation de la SPS est démontrée en couplant le QD unique à des structures magnéto-photoniques multidimensionnelles. À l'aide d'un champ magnétique externe, le mouvement contrôlable d'un seul QD a été démontré dans un environnement fluidique. En contrôlant l'amplitude et l'orientation du champ magnétique externe, la position et l'orientation de la SPS à base d'un QD ont été manipulées à la demande. Les propriétés optiques, magnétiques et mécaniques des dispositifs magnéto-photoniques hybrides ont été étudiées pour montrer les capacités multifonctionnelles de telles structuresThe thesis has been devoted to study the controlled coupling of a colloidal quantum dot (QD) based single photon source (SPS) into multidimensional polymeric photonic structures by using low-one photon absorption (LOPA) direct laser writing (DLW) technique. The thesis consists of three main parts:The first part addresses the characteristic optimization of the CdSe/CdS based SPS. The excitation wavelength dependence of the QDs was investigated. By using 532 nm, only the core of the QD is excited with the suppression of the Auger effects. Thus, this approach allows for obtaining the suppression of fluorescence intermittency and a stable single-photon emission at ambient conditions. In order to obtain the long-term high fluorescence quality of the QDs, we then studied the influence of the local dielectric medium on the optical properties of the QDs. By incorporating the QDs into a photoresist (SU-8), we demonstrated that the polymeric environment not only enables the long-term preservation of the QD with high photostability but also provides us excellent accessibility to fabricate polymeric structures containing SPS.In the second part, the LOPA-based DLW is employed for the coupling of single QD into various photonic structures. Two devices including submicropillar dielectric antenna and 3D membrane bulleye cavity are theoretically and experimentally investigated to enhance the fluorescence emission of the single QD in terms of far-field angular radiation pattern and the spontaneous radiative emission of the emitter.In the third part, the manipulation of SPS is demonstrated by coupling the single QD into multidimensional magneto-photonic structures. With the aid of an external magnetic field, the controllable movement of the coupled QD was performed in the fluidic environment. The position and orientation of the SPS coupled in the structure were manipulated on demand. The mechanical, magnetic and optical properties of the device are investigated showing the multifunctional capabilities of magneto-photonic structures
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Jagsch, Stefan Thomas [Verfasser], Axel [Akademischer Betreuer] Hoffmann, Axel [Gutachter] Hoffmann, and Donat Josef [Gutachter] As. "Towards a deterministic cavity-integrated III-nitride single-photon source with two-photon resonant control / Stefan Thomas Jagsch ; Gutachter: Axel Hoffmann, Donat Josef As ; Betreuer: Axel Hoffmann." Berlin : Technische Universität Berlin, 2020. http://d-nb.info/1215177836/34.
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Zhang, Jiaxiang [Verfasser], Oliver G. [Akademischer Betreuer] Schmidt, Oliver G. [Gutachter] Schmidt, and Armando [Gutachter] Rastelli. "Single- and entangled-photon emission from strain tunable quantum dots devices / Jiaxiang Zhang ; Gutachter: Oliver G. Schmidt, Armando Rastelli ; Betreuer: Oliver G. Schmidt." Chemnitz : Universitätsbibliothek Chemnitz, 2015. http://d-nb.info/1213813603/34.
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Schunk, Gerhard [Verfasser], Gerd [Akademischer Betreuer] Leuchs, Hugues de [Gutachter] Riedmatten, and Christoph [Gutachter] Marquardt. "Tunable single photons from resonant parametric down-conversion for efficient photon-atom coupling / Gerhard Schunk ; Gutachter: Hugues de Riedmatten, Christoph Marquardt ; Betreuer: Gerd Leuchs." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2018. http://d-nb.info/1160444250/34.
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Schunk, Gerhard Rainer [Verfasser], Gerd [Akademischer Betreuer] Leuchs, Hugues de [Gutachter] Riedmatten, and Christoph [Gutachter] Marquardt. "Tunable single photons from resonant parametric down-conversion for efficient photon-atom coupling / Gerhard Schunk ; Gutachter: Hugues de Riedmatten, Christoph Marquardt ; Betreuer: Gerd Leuchs." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2018. http://d-nb.info/1160444250/34.
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Close, Tom A. "Robust quantum phenomena for quantum information processing." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:95324cad-e44b-4bd8-b6e1-173753959993.
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This thesis is concerned with finding technologically useful quantum phenomena that are robust against real world imperfections. We examine three different areas covering techniques for spin measurement, photon preparation and error correction. The first research chapter presents a robust spin-measurement procedure, using an amplification approach: the state of the spin is propagated over a two-dimensional array to a point where it can be measured using standard macroscopic state mea- surement techniques. Even in the presence of decoherence, our two-dimensional scheme allows a linear growth in the total spin polarisation - an important increase over the √t obtainable in one-dimension. The work is an example of how simple propagation rules can lead to predictable macroscopic behaviour and the techniques should be applicable in other state propagation schemes. The next chapter is concerned with strategies for obtaining a robust and reliable single photon source. Using a microscopic model of electron-phonon interactions and a quantum master equation, we examine phonon-induced decoherence and assess its impact on the rate of production, and indistinguishability, of single photons emitted from an optically driven quantum dot system. We find that, above a certain threshold of desired indistinguishability, it is possible to mitigate the deleterious effects of phonons by exploiting a three-level Raman process for photon production. We introduce a master equation technique for quantum jump situations that should have wide application in other situations. The final chapter focusses on toric error correcting codes. Toric codes form part of the class of surface codes that have attracted a lot of attention due to their ability to tolerate a high level of errors, using only local operations. We investigate the power of small scale toric codes and determine the minimum size of code necessary for a first experimental demonstration of toric coding power.
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Hafenbrak, Robert [Verfasser]. "Tuning the exciton fine structure of single (In,Ga)As/GaAs quantum dots to realize a triggered entangled photon source / Robert Hafenbrak." München : Verlag Dr. Hut, 2011. http://d-nb.info/1013526325/34.
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Tartari, Enrico. "Study of localized defect-bound excitonic transitions in TMD-WSe2 monolayers and evanescent coupling to tapered optical nanofibers." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/22128/.
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The project has two main objectives. First, the demonstration of the existence of single photon emitters in WSe2 monolayers. We recognized localized defect-bound excitons as responsible for this. Second, the demonstration of the evanescent coupling of a localized defect-bound exciton emission to a tapered optical nano fiber. To achieve these goals, we produced a detailed study ofWSe2, starting from the fabrication process in the clean room, up to the characterization ofthe emission spectrum and the proof of the existence of single photon emitters. Then, before fabricating the nanofibers and demonstrating the coupling result, we tested the feasibility ofthe evanescent coupling with COMSOL and MATLAB simulations. In particular, we performed a detailed optical
characterization of two samples of WSe2 monolayers produced via exfoliation in clean room. We used an all dry deterministic transfer to encapsulate the samples in two layers of hexagonal boron nitride (hBN). We performed micro-photoluminescence, lifetime and degree of second-order temporal coherence measurements. We focused our attention in localized defect-bound excitons due to the high intensity PL signal and sharp
linewidth. Moreover, in this work we have demonstrated
the evanescent coupling of a single localized defect-bound exciton emitter with a tapered optical
nano fiber we produced. For the fabrication of the nanofiber, through COMSOL and MATLAB
simulations we found the right size to have a sufficiently intense evanescent
field to allow coupling to the emitter. We managed, through several repetitions, to produce
autonomously the nanofiber of the desired size. Finally we were able to demonstrate the feasibility of the evanescent coupling of the emission
to the fiber from a chosen localized defect-bound exciton. Thus, our results provide evidence of the
possibility to integrate quantum emitters in 2D materials with photonic structures.
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Bigourdan, Florian. "Nanoantennes plasmoniques." Thesis, Palaiseau, Institut d'optique théorique et appliquée, 2014. http://www.theses.fr/2014IOTA0020/document.
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Dans ce travail de thèse, on s’intéresse aux applications des concepts d’antenne pour la manipulation de la lumière. Aux fréquences optiques, les antennes métalliques font intervenir des modes de surfaces dit plasmoniques permettant une forte interaction lumière/matière dans des volumes hautement confinés. Pour tirer partie de cette propriété, on s’intéressera à trois applications des antennes plasmoniques. D’abord dans le cadre des sources de photons uniques, on présentera une étude théorique et expérimentale des performances d’émetteurs uniques en présence d’une antenne planaire métallique. Nous proposerons ensuite une stratégie pour améliorer les performances de l’antenne. Puis dans le cadre de la génération électrique de lumière par effet tunnel inélastique, on analysera la modification des propriétés de rayonnement en présence d’un petit cylindre métallique. Cette analyse ouvre la voie à la conception de sources électriques intégrées de plasmons de surface. Enfin dans le cadre de la détection de molécules en faible quantité, on étudiera théoriquement l’interaction d’un faisceau infrarouge avec une couche de molécules résonnantes déposées sur un miroir métallique nanostructuréThe work of this thesis has been devoted to a few applications of antenna concepts for the manipulation of light. In the optical range, surface modes called surface plasmon polaritons take place in the vicinity of metallic antennas, enabling a strong light/matter interaction within highly confined volumes. In order to take advantage of this property, three applications of plasmonic antennas will be investigated. First, in the case of single-photon sources, both theoretical and experimental studies of single-emitters performance when coupled to a planar metallic antenna will be presented. A strategy to enhance its performance will be studied theoretically. Then, in the case of electrical generation of light by inelastic electron tunneling, we will analyse the modification of radiation properties close to a metallic nano-rod. This analysis paves the way towards the design of integrated, compact electrical sources of surface plasmons. Finally, in the case of detecting a weak quantity of molecules, the interaction between an infrared light beam and a sub-nanometric layer of resonant molecules deposited on a nanostructured metallic mirror will be studied
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Gaignard, Maxime. "Une source efficace de photons uniques et indiscernables." Electronic Thesis or Diss., Université Grenoble Alpes, 2023. http://www.theses.fr/2023GRALY089.
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Dans les domaines des communications quantiques et du calcul quantique, la transmission d'information à l'aide de photons uniques garantis la sécurité de la communication et permet la mise en œuvre de calculs irréalisables avec nos ordinateurs « classiques ». L'un des éléments primordiaux à la réalisation de tels protocoles est la source de photons. Elle doit émettre, à la demande, un et un seul photon aux propriétés quantiques déterminées.L'objectif de ce projet de thèse est de caractériser une source de photons uniques et indiscernables, conçue et fabriquée au CEA-Grenoble, et qui consiste en une boite quantique semiconductrice d'arséniure d'indium (InAs) intégrée à une nanocavité d'arséniure de gallium (GaAs). Présentant un faible facteur de qualité, la nanocavité permet l'extraction efficace de photons sur une grande plage de longueurs d'ondes (30nm). De plus, grâce à son petit volume de mode, l'émission spontanée des boites quantiques en son sein peut être accélérée par un effet Purcell pouvant aller jusqu'à 6.Dans ce manuscrit de thèse, nous détaillons tout d'abord la mise en place et l'optimisation des dispositifs expérimentaux utilisés pour caractériser les photons émis par notre échantillon : Micro-photoluminescence, mesure du temps de vie radiatif, expérience Hanbury-Brown et Twiss (HBT) et expérience Hong-Ou-Mandel (HOM). Ensuite, nous présentons les résultats expérimentaux obtenus pour les photons émis par deux boites quantiques distinctes : L'une contenant des états d'excitons neutres, et la seconde, un état d'exciton chargé. Afin de photo-créer ces états d'excitons dans les boites quantiques, deux dispositifs d'excitation optique impulsionnelle ont été mis en place : L'excitation résonante à deux photons du biexciton neutre, et l'excitation quasi-résonante assistée par phonons longitudinaux acoustiques de l'exciton neutre et de l'exciton chargé. Nous présentons la mesure des trois figures de mérite d'une source de photon unique pour ces deux boites quantiques : La brillance, l'unicité des photons émis et leur indiscernabilité. Dans un second temps, nous nous intéresserons particulièrement à l'état d'exciton chargé et mesurerons le profil de sa raie d'émission et sa fonction d'autocorrélation sous excitation résonante continue. Ces résultats, réalisés au sein du groupe de nano-photonique de l'université de Bâle, constituent la première démonstration d'excitation continue sur ces nanostructures, ce qui est une agréable surprise étant donné leur petite taille.Pour terminer, nous nous pencherons sur l’effet de l’application de contraintes mécaniques sur la séparation en énergie des deux états de l’exciton neutre, appelée la « séparation de structure fine ». Lors de la cascade radiative de l’état du biexciton neutre, les deux photons émis sont intriqués en polarisation, et la fidélité de l’intrication dépend notamment de la séparation de structure fine. Nous étudierons ici un second échantillon, où les boites quantiques InAs sont intégrées à un microfil photonique de GaAs. En faisant fléchir le microfil, des contraintes mécaniques sont appliquées sur les boites quantiques, ce qui a pour effet de modifier l’énergie des états de l'excitons. Nous présenterons une étude expérimentale visant à observer un possible effet sur la séparation de structure fine.En conclusion, nous avons développé et optimisé divers dispositifs expérimentaux permettant la caractérisation de sources de photons pour des applications dans le domaine des communications quantiques et du calcul quantique. Pour une première version de ces nanostructure photonique, la brillance, l'unicité de l'émission et l'indiscernabilité des photons émis par nos boites quantiques intégrées dans des nanocavités sont très encourageantes pour la suite. Les prochains objectifs portent sur l'amélioration des nanocavités et sur la caractérisation plus approfondie des phénomènes de décohérence et du couplage mécanique entre les boites quantiques et ces structuresIn the fields of quantum communications and quantum computing, the transmission of information using single photons guarantees the security of the communication and enables calculations that would be impossible with our "classical" computers. One of the key elements in implementing such protocols is the photon source. It must emit, on demand, one and only one photon with specific quantum properties.The aim of this project is to characterise a source of single and indistinguishable photons, designed and manufactured at CEA-Grenoble, and consisting of an indium arsenide (InAs) semiconductor quantum dot integrated into a gallium arsenide (GaAs) nanocavity. With its low quality factor, the nanocavity enables photons to be extracted efficiently over a wide range of wavelengths (30nm). In addition, thanks to its small mode volume, the spontaneous emission of quantum dots within it can be accelerated by Purcell effect (Purcell factor up to 6).In this manuscript, we first detail the implementation and the optimisation of the experimental setups used to characterise the photons emitted by our sample : microphotoluminescence, radiative lifetime measurement, Hanbury-Brown and Twiss (HBT) experiment and Hong-Ou-Mandel (HOM) experiment. Then, we present the experimental results obtained for photons emitted by two distinct quantum dots : One containing neutral exciton states, and the second, containing a charged exciton state. In order to photo-create these exciton states in the quantum dots, two pulsed optical excitation schemes were implemented: the two-photon resonant excitation of the neutral biexciton, and the phonon-assisted quasi-resonant excitation of the neutral and charged excitons. We present the measurement of the three figures of merit of a single photon source for these two quantum dots : the brightness, the single-photon purity and the indistinguishability of the emitted photons. In a second phase, we will focus on the charged exciton state and measure the profile of its emission line and its autocorrelation function under continuous resonant excitation. These results, achieved within the nano-photonics group of the University of Basel, constitute the first demonstration of continuous excitation on these nanostructures, which is a good surprise given their small size.Finally, we will look at the effects of the application of mechanical stress on the energy separation of the two neutral exciton states, known as the "fine structure splitting" (FSS). During the radiative cascade of the neutral biexciton state, the two photons emitted are entangled in polarisation, and the fidelity of the entanglement depends in particular on the FSS. Here, we will consider a second sample, where the InAs quantum dots are embedded in a GaAs photonic nanowire. By bending the nanowire, mechanical stresses are applied to the quantum dots, which will modify the energy of the exciton states. We will present an experimental study aimed at observing a possible effect on the fine structure splitting.In conclusion, we have developed and optimised various experimental setups for characterising photon sources for applications in the fields of quantum communications and quantum computing. For a first version of these photonic nanostructures, the brightness, the single-photon purity and the indistinguishability of the photons emitted by our quantum dots integrated into nanocavities are very encouraging for the future. The next objectives are to improve the nanocavities and to characterise the decoherence phenomena and the mechanical coupling between the quantum dots and these nanostructures
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Babinec, Thomas Michael. "Topics in Nanophotonic Devices for Nitrogen-Vacancy Color Centers in Diamond." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10461.
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Recently, developments in novel and high-purity materials allow for the presence of a single, solitary crystalline defect to define the electronic, magnetic, and optical functionality of a device. The discrete nature of the active dopant, whose properties are defined by a quantum mechanical description of its structure, enables radically new quantum investigations and applications in these arenas. Finally,there has been significant development in large-scale device engineering due to mature semiconductor manufacturing techniques. The diverse set of photonic device architectures offering light confinement, guiding, and extraction is a prime example. These three paradigms – solitary dopant photonics and optoelectronics (solotronics), quantum science and technology, and device engineering – merge in the development of novel quantum photonic devices for the next generation of information processing systems. We present in this thesis a series of investigations of optical nanostructures for single optically active spins in single crystal diamond. Chapter 1 introduces the Nitrogen-Vacancy (NV) color center, summarizes its applications, and motivates the need for their integration into photonic structures. Chapter 2 describes two prototype nanobeam photonic crystal cavities for generating strong light-matter interactions with NV centers. The first device consists of a silicon nitride photonic crystal nanobeam cavity with high quality factor \(Q \sim 10^5\) and small mode volume \(V \sim 0.5*(\lambda/n)^3\). The second device consists of a monolithic diamond nanobeam cavity fabricated with the focused ion beam (FIB) directly in a single crystal diamond sample. Chapter 3 presents a high-efficiency source of single photons consisting of a single NV center in a photonic diamond nanowire. Early FIB prototypes are described, as is the first successful realization of the device achieved via reactive ion etching nanowires in a single crystal diamond containing NV centers, and finally a variation of this approach based on incorporation of NV centers in pure diamond via ion implantation. In chapter 4 we consider the optimal design of photonic devices offering both collection efficiency and cavity-enhancements and extend the model of the NV center to include photonic effects. In chapter 5 we briefly introduce a novel optically active spin discovered in a diamond nanowire. Finally, in chapter 6 we conclude with several proposals to extend this research program.Engineering and Applied Sciences
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Kiyohara, Takayuki. "Generation of heralded multi-photon parallel state for realizing a large-scale photonic quantum circuit." Kyoto University, 2020. http://hdl.handle.net/2433/253284.
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Callsen, Gordon [Verfasser], Axel [Akademischer Betreuer] Hoffmann, Matthew [Akademischer Betreuer] Phillips, Janina [Akademischer Betreuer] Maultzsch, and Bernard [Akademischer Betreuer] Gil. "Advanced optical signatures of single, wurtzite GaN quantum dots : from fundamental exciton coupling mechanisms towards tunable photon statistics and hybrid-quasiparticles / Gordon Callsen. Gutachter: Axel Hoffmann ; Matthew Phillips ; Janina Maultzsch ; Bernard Gil. Betreuer: Axel Hoffmann ; Matthew Phillips." Berlin : Technische Universität Berlin, 2015. http://d-nb.info/1071598015/34.
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Schietinger, Stefan. "Investigation, manipulation, and coupling of single nanoscopic and quantum emitters." Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät I, 2012. http://dx.doi.org/10.18452/16624.
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Die hier vorgelegte Dissertation beschäftigt sich mit Untersuchungen an nanoskopischen Emittern und den Möglichkeiten, deren Fluoreszenzverhalten durch kontrollierte Ankopplung an photonische und plasmonische Strukturen zu beeinflussen. Zum einen werden mit Ytterbium- und Erbium-Ionen kodotierte NaYF4 -Nanokristalle untersucht, die hervorragende Eigenschaften bei der Umwandlung von niederenergetischen Photonen in solche höherer Energie besitzen. Das so entstehende Fluoreszenzlicht einer Ansammlung von Nanokristallen wird auf seine Abhängigkeit von der Anregungsintensität untersucht. Mit der Hilfe eines Rasterkraftmikroskops (AFM) wird eine Abhängigkeit der spektralen Zusammensetzung des Fluoreszenzlichts einzelner Nanokristalle von deren Größe im Bereich von wenigen bis 50 nm aufgezeigt. Durch gezielte Manipulation mit dem AFM werden ebenfalls einzelne Nanokristalle an Goldnanokügelchen gekoppelt und die Mechanismen der beobachteten plasmonischen Verstärkung der Emission durch zeitaufgelöste Messungen analysiert. Einzelne Stickstoff-Fehlstellen-Zentren in Nanodiamanten werden in einem zweiten Themenkomplex als Einzelphotonenquellen eigesetzt. Diese werden durch den Einsatz einer Nahfeld-Sonde auf Mikrokugel-Resonatoren aufgebracht, wodurch die Emission aufgrund der Ankopplung an die Flüstergalerie-Moden der Kugeln die typischen, scharfen Überhöhungen im Spektrum aufweist. Diese Methode lässt sich nicht nur verwenden, um zwei oder mehr Emitter an die selben Resonanzen einer Kugel zu koppeln. Es ist auch möglich, die Kugeln in einem Vorbereitungsschritt zu charakterisieren, und so kann insbesondere eine spektrale Übereinstimmung zwischen einer der Resonanzen und dem Emitter erreicht werden. Desweiterne wird demonstriert, wie durch die Kopplung an eine plasmonische Antenne aus Goldnanokugeln mittels AFM auch die Effizienz der Einzelphotonenquelle gesteigert werden kann.The topic of the dissertation presented here is the investigation of nanoscopic emitters and the possibilities to influence their fluorescence behavior by controlled coupling to photonic and plasmonic structures. NaYF4 nanocrystals codoped with ytterbium and erbium are investigated since they provide excellent properties in upconverting of low-energetic photons to photons with higher energy. The fluorescence light that is generated in this process of a small cluster of nanocrystals is investigated on its dependence on the excitation intensity. With the help of an atomic force microscope (AFM) a dependence of the spectral composition of the fluorescence light from single nanocrystals on their size ranging between a few to 50 nm is demonstrated. By selective manipulation with the AFM, individual nanocrystals are coupled to gold nanospheres and the mechanisms of the observed plasmonic amplification of the emission is analyzed with time-resolved measurements. Single nitrogen–vacancy centers in nanodiamonds are employed as single-photon sources in a second subject area. A near-field probe is employed to attach these single quantum systems to microspherical resonators, by which their emission features the typical peaks in the spectrum due to the coupling to the whispering gallery modes of the spheres. This method can not only be applied to couple two or more single-photon emitters to the very same modes of a microsphere, but the resonators themselves can be pre-characterized to match one of the modes with the emitter. Furthermore, it will be demonstrated how the efficiency of a single-photon source can be enhanced by coupling the nitrogen-vacancy center to a plasmonic antenna made of gold nanospheres.
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Elvira, Antunez David. "Sources à boîtes quantiques semiconductrices pour la nanophotonique et l'information quantique aux longueurs d'onde des télécommunications." Phd thesis, Université Paris Sud - Paris XI, 2012. http://tel.archives-ouvertes.fr/tel-00750816.
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Le siècle dernier a vu l'accomplissement de la mécanique quantique, du traitement de l'information etde l'optique intégrée. Aujourd'hui, ces trois domaines se rencontrent pour donner naissance à l'optiqueintégrée pour les communications quantiques. Un des enjeux aujourd'hui dans ce domaine est ledéveloppement de sources de photons unique aux longueurs d'onde des télécommunications fibrés.Durant ce travail de thèse les émetteurs étudiés sont des boîtes quantiques d'InAsP épitaxiés parEPVOM (Epitaxie en Phase Vapeur aux OrganoMétalliques). On démontrera que ces objets uniquessont capables d'émettre des états quantiques de la lumière grâce à une expérience de dégroupement dephotons. De plus la spectroscopie de ces objets sera déduite des études résolues en temps. Lapossibilité d'intégrer ces objets au sein de nanocavité de taille ultime permet de modifier leur tauxd'émission spontanée, ainsi les résultats obtenus grâce aux cavités métalliques permettent d'observerune accélération de l'émission spontanée sur une large bande spectrale. Finalement il a été mis enévidence une forte modification de l'émission d'un ensemble de boîtes quantiques entre 4K et 300K,en utilisant une technique originale basé sur l'effet laser.
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Gouzien, Élie. "Optique quantique multimode pour le traitement de l'information quantique." Thesis, Université Côte d'Azur (ComUE), 2019. http://www.theses.fr/2019AZUR4110.
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Cette thèse étudie l’optique quantique multimode, aussi bien du point de vue de la génération que celui de la détection. Elle s’articule autour de trois volets. Nous étudions la génération de lumière comprimée multimode dans une cavité. Pour cela nous considérons la forme la plus générale de hamiltonien quadratique, permettant entre autres de décrire l’utilisation de plusieurs pompes dans un matériau effectuant du mélange à quatre ondes. Une approche combinant fonctions de Green et décompositions de matrices symplectiques est décrite. Cette théorie générique est appliquée à des cas particuliers. Dans un premier temps, des exemples en basse dimension sont donnés. Ensuite, une configuration d’oscillateur paramétrique optique pompé de manière synchrone (SPOPO) est décrite et étudiée ; les résultats obtenus montrent que ce système a un comportement très différent de celui du SPOPO utilisant une non-linéarité d’ordre 2. Ces travaux ouvrent la voie à la réalisation de peignes de fréquences quantiques avec des micro-résonateurs en anneau gravés sur silicium. Un autre problème examiné est celui de prendre en compte l’information temporelle obtenue lors du clic d’un détecteur de photon unique. Pour cela nous utilisons un formalisme multimodal temporel afin d’expliciter les opérateurs décrivant la mesure. Les principaux défauts des détecteurs réels, dont la gigue temporelle, l’efficacité finie et les coups d’obscurité sont pris en compte. L’utilisation des opérateurs est illustrée par la description d’expériences usuelles de l’optique quantique. Enfin, on montre que la lecture du temps de clic du détecteur permet d’améliorer la qualité de l’état généré par une source de photons annoncés. En troisième partie nous présentons un schéma de génération d’intrication hybride entre variables continues et discrètes, pour laquelle la partie discrète est encodée temporellement. Ce schéma est analysé en détail vis-à-vis de sa résistance aux imperfections expérimentalesThis thesis studies multimode quantum optics, from generation to detection of light. It focuses on three main parts. Multimode squeezed states generation within cavity is studied. More specifically, we take into account general quadratic Hamiltonian, which allows describing experiments involving arbitrary number of modes and pumps within a medium performing four-wave mixing. We describe a generic approach combining Green functions and symplectic matrix decomposition. This general theory is illustrated on specific cases. First, low-dimensional examples are given. Then, a synchronously pumped optical parametric oscillator (SPOPO) is described and studied; it shows a very distinct behavior from that of the SPOPO using second order non-linearity. This work opens way to the realization of quantum frequency combs with ring micro-resonators engraved on silicon. Single-photon detectors are described taking into account temporal degrees of freedom. We give positive-valued measurement operators describing such detectors including realistic imperfections such as timing-jitter, finite efficiency and dark counts. Use of those operators is illustrated on common quantum optics experiments. Finally, we show how time-resolved measurement allows improving the quality of state generated by single-photon heralded source. In the third part we propose a protocol for generating a hybrid state entangling continuous and discrete variables parts, for which the discrete part is time-bin encoded. This scheme is aanalysed in detail with respect to its resilience to experimental imperfections
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Bin, Ngah Lufti Arif. "Synchronisation toute optique d’un réseau de communication quantique." Thesis, Nice, 2015. http://www.theses.fr/2015NICE4141/document.
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Ce manuscrit expose le développement de ressources fondamentales pour les communications quantiques à longues distances basées sur les technologies des fibres optiques télécoms et des guides d'onde optiques non linéaires. Après une introduction générale sur les communications quantiques, cette thèse est structurée en trois parties principales. La première partie illustre le développement de deux sources pour la génération de paires de photons intriqués en polarisation et émis à une longueur d'onde télécom via conversion paramétrique spontanée (SPDC) dans des guides d'ondes non linéaires intégrés sur niobate de lithium périodiquement polarisé. Les sources s'appuient respectivement sur un accord de phase de type-II et un accord de phase de type-0 et sur des solutions de filtrage et d'interférométrie mises en place après le cristal non linéaire. Dans la seconde partie, sont discutées les réalisations de deux sources de photons uniques annoncés haut débit. La première s'appuie sur le multiplexage spatial sur puce de photons uniques annoncés. La seconde exploite le multiplexage temporel passif grâce à l'utilisation d'un laser télécom cadencé à 10 GHz. Enfin, nous présentons une approche tout-optique visant la synchronisation de sources distantes de paires de photons intriqués, agencées selon une architecture de type relais quantique distribué. Cette technique innovante repose sur l'utilisation d'un laser télécom impulsionnel en tant qu'horloge optique de référence. Cette horloge autorise la synchronisation de l'émission de paires de photons dans la bande C des télécoms en deux lieux distants. Des résultats préliminaires d'interférence à deux photons sont montrés et discutésThis manuscript reports the development of fundamental resources for long distance quantum communication based on fibre telecom technology and non-linear optical waveguides. After a general introduction on quantum communication, the thesis is structured along three parts. The first part illustrates the development of two photonic polarization entanglement sources suitable for quantum networking. Both sources generate paired photons at telecom wavelength via spontaneous parametric down conversion (SPDC) in periodically poled lithium niobate waveguides (PPLN/W). They rely on type-II and type 0 phase matching, respectively. In the second part, two high quality heralded single photon sources are highlighted. The first one relies on on-chip generation and spatial multiplexing of heralded single photons towards achieving higher bit rates. The second one takes advantage of passive temporal multiplexing of a single SPDC process. Finally, an all-optical approach towards efficient and accurate synchronization of remote entangled photon pair sources within quantum relay architecture over long distances is presented. This particular synchronization technique highlights the use of ultra-fast picosecond pulsed telecom fiber laser, operating at 2.5 GHz repetition rate, acting as a master optical clock, enabling to accurately synchronize the emission of photon pairs in the telecom C-band of wavelengths at two remote locations. This innovative approach is applied for synchronizing two remote PLLN/W based sources operated at 2.5 GHz, and preliminary results on two-photon interference obtained with single photons coming from each source are shown and discussed
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Nilsson, Jonas. "Génération électrique de lumière intriquée destinée au transfert optique d'information quantique." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2013. http://tel.archives-ouvertes.fr/tel-00957826.
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Les boites quantiques de semiconducteurs représentent une voie attractive pour la réalisation de sources de photon efficaces pour le transfert quantique de l'information, avec un fort potentiel de miniaturisation et d'intégration. Dans ce travail, les paires de photons intriqués sont générées via le déclin radiatif de bi-excitons, à partir de boite quantiques d'InAs auto-assemblées placé dans une jonction p-i-n. Dans une première série d'expérience d'interférence à deux photons, nous avons démontré des corrélations de polarisation non classiques et la capacité de deux photons à interférer. L'intrication a été démontrée avec une fidélité de 0.87±0.04, et une visibilité des interférences de 0.60±0.05. Nous avons ensuite réalisé le premier téléporteur injecté électriquement dans un circuit à fibre monomode. Une fidélité moyenne de 0.704±0.016 a été mesurée pour 6 états distribués symétriquement sur la sphère de Poincaré, ce qui supérieur à la limite classique de 2/3 et prouve la téléportation. Un dispositif modifié de téléportation permettant d'injecter des photons à partir d'un laser continu indépendant a été développé. L'interférence à deux photons entre sources différentes a été démontrée et des battements quantiques observés. La téléportation quantique des états de polarisation portés par les photons a été obtenue avec une fidélité moyenne 0.76±0.012. Le contrôle du spin des charges confinés dans les nanostructures tels que les boites quantiques requiert une compréhension profonde de la physique des matériaux constituant, y compris au niveau nucléaire. Ainsi, nous avons démontré le contrôle électrique de l'interaction hyperfine entre les spins électroniques et nucléaires en utilisant un composant à charge ajustable. La modélisation suggère que le mécanisme est contrôlé par le temps de corrélation hyperfine de l'électron et le temps de dépolarisation du noyau.
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Chuang, Ya-Wen, and 莊雅雯. "Localized surface plasma and single photon source." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/88876273872429617306.
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碩士國立清華大學
物理系
102
In order to effectively use single photon sources, we designed waveguides for single photons. These waveguides were nano-scale array structures of metal-coated silicon nanorods and allowed the transport of electromagnetic field with localized surface plasma. By observing the reflectance spectra of different array structures, we investigated the influence of geometrical structures on the resonant enhancement of localized surface plasma. In addition, we managed to build a single photon source by focusing a pulsed laser to excite single quantum dots. Experiments were conducted at room temperature. The arrays of silicon nanorods were constructed on silicon wafers by electron beam lithography. The diameter of each nanorod was 100nm ~ 600 nm and the size of each array was 2μm ~ 2mm. After the arrays were fabricated, silver or gold thin films were deposited on the surfaces either by electron beam evaporation or sputtering. In the setup of single photon source, we used a 405nm picosecond pulsed diode laser and carboxyl CdSe/ZnS quantum dots with emission maxima near 705nm. In order to effectively use single photon sources, we designed waveguides for single photons. These waveguides were nano-scale array structures of metal-coated silicon nanorods and allowed the transport of electromagnetic field with localized surface plasma. By observing the reflectance spectra of different array structures, we investigated the influence of geometrical structures on the resonant enhancement of localized surface plasma. In addition, we managed to build a single photon source by focusing a pulsed laser to excite single quantum dots. Experiments were conducted at room temperature. The arrays of silicon nanorods were constructed on silicon wafers by electron beam lithography. The diameter of each nanorod was 100nm ~ 600 nm and the size of each array was 2μm ~ 2mm. After the arrays were fabricated, silver or gold thin films were deposited on the surfaces either by electron beam evaporation or sputtering. In the setup of single photon source, we used a 405nm picosecond pulsed diode laser and carboxyl CdSe/ZnS quantum dots with emission maxima near 705nm. In the future, we will study the interaction between the single photon source and different nano-scale array structures of nanorods. We will also investigate the effective interaction between two single photons that will be generated at opposite ends of one waveguide. The former can be applied to efficient use of single photon source; on the other hand, the latter is useful in quantum teleportation, quantum information storage and the generation of entangled biphotons.
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Wu, Ching-Jung, and 吳錦榮. "Studies of Single-Molecule Spectroscopy by a Pulsed Tunable Dye Laser Source." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/77650404318199057598.
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Ovvyan, Anna. "Nanophotonic circuits for single photon emitters." Doctoral thesis, 2018. http://hdl.handle.net/2158/1175896.
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Nanophotonic circuits for single photon emitters. The work demonstrated in this thesis is dedicated to the engineering, simulation, fabrica-tion and investigation of the essential element base to develop hybrid fully integrated nanopho-tonic circuit with coupled single photon emitter on chip. Combining several individually opti-mized stages of photonic devices, interconnected by nanoscale waveguides on chip with eva-nescently coupled single photon emitter, is a key step to the realization of such a scheme. The main requirements which should be satisfied for building such a hybrid system on-chip, and are thus the subject of this Thesis, are, namely: integration of single photon photostable source with high Quantum Yield (QY) on chip, efficient coupling of the emitted light to nanophotonic cir-cuits, and efficient filtering of the excitation light.
Silicon nitride-on-insulator was used in all the projects described in this Thesis as the platform for the realization of photonic circuits. It provides low-loss broadband optical transparency covering the entire visible range up to the near infrared spectrum. Furthermore, sufficiently high refractive index contrast of Si3N4 on SiO2 enables tight confinement of the mode in the waveguide structure and the realization of photonic circuits with small footprint.
A drastic increase of the coupling efficiency of the emitted light into the waveguide mode can be achieved by placing single-photon emitter on photonic crystal cavity because of its high Quality factor and small mode volume enabling a high Purcell enhancement.
To this end, a novel cross-bar 1D freestanding photonic crystal (PhC) cavity was developed for evanescent integration of single photon emitter, in particular Nanodiamonds (NDs), onto the region of the cavity. The novelty of this photonic structure is that collection of emitted light is provided via waveguide, which consists of PhC, whereas direct optical excitation is obtained through a crossed waveguide in the orthogonal direction of the in-plane cavity.
Optimization of the PhC cavity architecture was performed via rounds of simulations and ver-ified by experimental measurements of fabricated devices on chip, which were found in excel-lent agreement.
The next round of simulations was performed to define an optimal position of the source in the cavity region to achieve maximum Purcell enhancement, which was realized via Local Density of States (LDOS) computation. Thus, placing a single photon emitter into a determined position on the cavity region of the developed cross-bar 1D freestanding PhC enables an increase in the transmission coupling efficiency into cavity up to =71% in comparison with computed 41% in the case of coupling into waveguide mode of cross-bar structure without PhC.
To block the pump light and at the same time transmit the fluorescent emitted light, compact and low-loss cascaded Mach–Zehnder interferometers (MZIs) tunable filters in the
visible region embedded within nanophotonic circuit, were realized. Tunability was provided via thermo-optic effect. The design of this device, namely geometry and shape of the microheater, was optimized via thermo-optic measurements, to achieve low electrical power consumption (switching power of 12.2 mW for the case of a spiral-shape microheater), high filtration depth and low optical insertion loss. The novel design with double microheaters on top of both arms of single and cascaded MZIs allows doubling the range of the shifting amplitude of the interference fringes. The demonstrated architecture of tunable filter is multifunctional, namely allowing transmission and filtering of the desired wavelengths in a wide wavelength range. In particular, filtration depth beyond 36.5 dB of light with 532 nm wavelength and simultaneous transmission of light with 738 nm wavelength, which correspond respectively to excitation and emission wavelength of the silicon-vacancy color center in diamond, was demonstrated.
The results were published in Ovvyan, A. P.; Gruhler, N.; Ferrari, S.; Pernice, W. H. P. Cascaded Mach-Zehnder interferometer tunable filters. Journal of Optics 2016, 18, 064011 https://doi.org/10.1088/2040-8978/18/6/064011
Another filter with non-repetitive stopband with bandwidth of several nanometers was developed in this thesis. A non-uniform Bragg grating filter with novel double Gaussian apodization was proposed, whose fabrication required a single lithography step. This optimized Bragg filter provides a 21 dB filtration depth with a 3-dB bandwidth of 5.6 nm, insuring negligible insertion loss in the best case, while averaged insertion loss in reflected signal is 4.1dB (including loss in splitter).
One of the first Hybrid organic molecule Dibenzoterrylene (DBT) coupled on chip to a nanophotonic circuit was demonstrated in this thesis. DBT is a photostable single photon source in the near infrared spectrum at room and at cryogenic temperature, with almost unitary quan-tum yield. In order to protect the molecule against oxidization DBT was embedded in a host matrix – thin Anthracene crystal (DBT:Ac), which increases photostability.
Mirror enhanced grating couplers were employed as convenient output ports for ridge Si3N4 waveguide to detect single photons emitted from integrated Dibenzoterrylene (DBT) molecules at room temperature. The coupling ports were designed for waveguide structures on transparent silica substrates for light extraction from the chip backside. These grating ports were employed to read out optical signal from waveguides designed for single-mode operation at λ=785 nm.
DBT molecule was coupled evanescently to the waveguide, and upon excitation of isolated single molecule, emitted single photon signal was carried inside the waveguide to the outcou-pling regions. Using a Hanbury Brown and Twiss setup pronounced antibunching dip was read out from a single molecule via the grating couplers, which confirms the quantum nature of the outcoupled fluorescent light. Simulated and measured transmission coupling efficiency of sin-gle photon emission into the waveguide mode equals =42%.
The results were published in P. Lombardi*, A. P. Ovvyan*, S. Pazzagli, G. Mazzamuto, G. Kewes, O. Neitzke, N. Gruhler, O. Benson, W. H. P. Pernice, F. S. Cataliotti, and C. Toninelli. Photostable Molecules on Chip: Integrated Sources of Nonclassical Light. ACS Photonics 2018, 5, 126−132, DOI: 10.1021/acsphotonics.7b00521.
* P. Lombardi and A. P. Ovvyan contributed equally to this work.
Engineered nanophotonic elements integrated in optical circuits with coupled single photon emitter on chip allow simultaneously to enhance the emitted light by coupling it into resonant PhC cavity modes, to spatially separate the excitation light from the enhanced single photon emission and to filter out pump light. Enhancement of the emission rate leads to a sig-nificant increase of the coupling efficiency into cavity. Beforehand performed simulations were an essential step in order to design, build and optimize the architecture of the nanophotonic devices. Local Density of States enhancement computation was especially necessary to pre-cisely determine optimized position of the source on PhC cavity region to obtain maximum enhancement of the emission rate. To evaluate transmission coupling efficiency of emitted light into the cavity (β-factor), an extra round of simulations was performed.
The integrated photonic elements investigated and optimized in this Thesis, will be further employed for the realization of hybrid photonic circuits with integrated single photon sources: silicon-vacancy, nitrogen-vacancy centers in diamond as well as single organic molecule and semiconducting single-walled carbon nanotubes.
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Wang, Chunlang [Verfasser]. "A solid-state single photon source based on color centers in diamond / Chunlang Wang." 2007. http://d-nb.info/985516453/34.
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Day, Jason Owen. "Progress towards the creation of an on-demand single photon source using Rydberg atoms." 2008. http://www.library.wisc.edu/databases/connect/dissertations.html.
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Tsai, Pin-Ju, and 蔡秉儒. "Development of photon-pair source and quantum storage of heralded single photons in the atomic quantum memories." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/v6g256.
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博士國立臺灣大學
物理學研究所
107
Photon-pair source plays an important role in long-distance quantum communication. On the one hand, photons propagate at the speed of light to transfer the information. On the other hand, the strong quantum correlation between the two photons in a photon pair also allows one to distribute quantum information to different nodes while maintaining absolute security. However, in long-distance quantum communication, the communication distance is limited by the loss in the optical fiber for guiding photons. To solve this problem, the concept of the quantum repeater was proposed. In a quantum repeater, the quantum entanglement transfers to another group of photon pairs through entanglement swapping in each repeater station to extend the entanglement distribution distance, before it becomes weak and noisy. By repeating such a process in each two nearby nodes, the entanglement can be extended to the full distance and thus realized the long-distance quantum communication. In the quantum repeater protocol, an important process is to temporarily store the flying photons into the quantum memories at the repeater station, in order to synchronize another set of photons that are ready to perform the entanglement swapping. For this reason, the realization of quantum storage of single photons is an important milestone in achieving long-distance quantum communication. One quantum storage method is to utilize the electromagnetically-induced-transparency(EIT) mechanism established in the platform of cold atoms. In the EIT mechanism, the quantum state of light is converted into the ground-state coherence of atoms and stored in the atomic medium through adiabatic ramping of the control field. After a period of storage, the control light is switched on, the quantum state of the light can be reconstructed back from the atomic system. However, since quantum memories are built on the basis of an atomic system, the linewidth and frequency of the single photons prepare be stored are strongly limited. The spontaneous parametric down-conversion (SPDC) in nonlinear crystals provide a common and practical method for preparing nonclassical light such as photon pairs. In this process, a high-frequency photon is converted into a pair of time-frequency entangled photon pairs, usually called idler and signal. The idler photons are used to inform the generation of another signal photon in the photon pair. Therefore, this type of photon source is also called the heralded single-photon source. However, the bandwidth of photon pairs produced by SPDC is typically much larger than the level of atomic linewidth, and thus greatly reduces the interaction strength between light and atoms, thereby increasing the difficulty of storing the single photons. In this work, we overcome the difficulties mentioned above and demonstrate the quantum storage of single photons from SPDC in the atomic memories. This thesis is mainly divided into two parts. First, in order to conquer the high bandwidth of SPDC, we use cavity-enhanced SPDC to construct a narrow-band, single-mode, and nondegenerate photon source. To maintain system stability, we have developed a time-division multiplexing locking scheme to maintain the double resonant condition for cavity and simultaneously lock the frequency of the generated photon pairs at atomic transition. Thanks for the stability of the locking system, the photon source generation rate is greatly improved, and that also makes the quantum light source become a very suitable source for use in an atomic system. In this photon source, we get the photon pair generation rate and the count rate of 7.24x10^5 and 6142 s^-1 mW^-1, respectively. The correlation time of the photon pairs are 21.6 (2.2) ns, and the corresponding bandwidth is 2πx6.6(6) MHz. Based on the above data, we estimate the spectral brightness of the photon source to be 1.06x10^5 s^-1 mW^-1 MHz^-1, which is a relatively high value for the photon-pair source in single-mode operation. After completing the preparation of the photon pair, we further send the generated non-classical light to the atomic quantum memories in the next phase of the experiment. In this experiment, we use quantum memories based on EIT to achieve quantum storage and manipulation of photon pairs generated by the cavity-enhanced SPDC. First, in order to ensure the compatibility between the photon source and the atomic system, we tested a series of slow light experiments and estimated their quantum fidelity. The results show a good agreement between the theory and the experiment. After that, we further perform the quantum storage and manipulation of the heralded single photon. According to different storage and manipulation conditions, the temporal correlation or waveform of the photon pairs can be controlled by the quantum memories. This manipulation process not only allows us to manipulate the classical properties of photon pairs, such as bandwidth and group velocity but also enhances the non-classical correlation and quantum fidelity of reading photons. We achieve quantum storage with a storage efficiency of about 40% and the non-classical correlation of g^(2)s,i=5.87. In addition, though the manipulation process, we can further increase the non-classical correlation to g^(2)s,i=7.5, and the quantum fidelity can be effectively raised to the maximum limit of the condition. Our photon-pair source is very compact and its output is the single-mode operation which allows direct application without the complication of adding external filters. In addition, we demonstrate the source can be deployed for the atomic quantum memory to store a manipulate photon pair properties. Our scheme provides a compact non-classical light source solution for atomic memories systems. The setup of the photon source can also be easily extended to long-distance and large-scale quantum-communication systems. We believe that these efforts will be helpful in the field of quantum communication, especially the implementation of the quantum repeater.
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Henderson, Matthew Ryan. "Nanodiamond in optical fibre." Thesis, 2013. http://hdl.handle.net/2440/83262.
Full textAbstract:
Diamond, prized as both a gemstone and a cutting and polishing material, has recently been recognised for another remarkable property, a host of optically active colour centre defects. With the rise of interest in these colour centres, due to the unique optical properties, comes a need for interfacing with other optical platforms. Recent advances have attempted to fabricate optical structures from the diamond itself, or to combine these colour centres with the well-known fabrication techniques of other materials by placing nanodiamond crystals on the surface of other structures, such as microdisks, microspheres, and optical fibres. This thesis presents a new approach to this integration by demonstrating the fabrication of a hybrid nanodiamond-glass material. This technique embeds the nanodiamond within the optical structure, offering interaction with the bound optical fields, protection, and ease of fabrication. A range of optical structures has previously been fabricated from the chosen glass, tellurite, and fabrication of an optical fibre is demonstrated here. Also presented is the derivation of a model describing coupling of an emitter to an optical fibre. While used here to investigate coupling of diamond colour centres to the optical fibre modes, it is more generally applicable to any emitter. These results show the first steps of a new approach to diamond integrated photonics.Thesis (Ph.D.) -- University of Adelaide, School of Chemistry and Physics, 2013