Bibliografie tematiche / Quantum optics Measurement

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Letteratura scientifica selezionata sul tema "Quantum optics Measurement"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 31 gennaio 2023

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Articoli di riviste sul tema "Quantum optics Measurement"

Walls, DF. "Quantum Measurements in Atom Optics". Australian Journal of Physics 49, n. 4 (1996): 715. http://dx.doi.org/10.1071/ph960715.

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We review recent progress in atom optics. We describe new quantum measurements based on the entanglement of quantum states of a light field with atomic external degrees of freedom. Examples include the quantum non-demolition measurement of the photon number in a cavity and the measurement of atomic position.

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Hradil, Z. "Phase measurement in quantum optics". Quantum Optics: Journal of the European Optical Society Part B 4, n. 2 (aprile 1992): 93–108. http://dx.doi.org/10.1088/0954-8998/4/2/004.

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Xavier, Jolly, Deshui Yu, Callum Jones, Ekaterina Zossimova e Frank Vollmer. "Quantum nanophotonic and nanoplasmonic sensing: towards quantum optical bioscience laboratories on chip". Nanophotonics 10, n. 5 (1 marzo 2021): 1387–435. http://dx.doi.org/10.1515/nanoph-2020-0593.

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Abstract Quantum-enhanced sensing and metrology pave the way for promising routes to fulfil the present day fundamental and technological demands for integrated chips which surpass the classical functional and measurement limits. The most precise measurements of optical properties such as phase or intensity require quantum optical measurement schemes. These non-classical measurements exploit phenomena such as entanglement and squeezing of optical probe states. They are also subject to lower detection limits as compared to classical photodetection schemes. Biosensing with non-classical light sources of entangled photons or squeezed light holds the key for realizing quantum optical bioscience laboratories which could be integrated on chip. Single-molecule sensing with such non-classical sources of light would be a forerunner to attaining the smallest uncertainty and the highest information per photon number. This demands an integrated non-classical sensing approach which would combine the subtle non-deterministic measurement techniques of quantum optics with the device-level integration capabilities attained through nanophotonics as well as nanoplasmonics. In this back drop, we review the underlining principles in quantum sensing, the quantum optical probes and protocols as well as state-of-the-art building blocks in quantum optical sensing. We further explore the recent developments in quantum photonic/plasmonic sensing and imaging together with the potential of combining them with burgeoning field of coupled cavity integrated optoplasmonic biosensing platforms.

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Walls, DF, MJ Collett, EP Storey e SM Tan. "Quantum Measurements in Atomic Optics". Australian Journal of Physics 46, n. 1 (1993): 61. http://dx.doi.org/10.1071/ph930061.

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We consider atoms traversing a cavity filled with an optical field. When the atoms are well detuned from the optical resonance the output momentum distribution of the atoms is found to be a sensitive probe of the photon statistics of the light field. Near resonance spontaneous emission smears the diffractive peaks. We obtain a good fit to the experimental data of Gould et at. (1991). As the atoms pass through the optical field they impart a position-dependent phase shift to the field. By making a quadrature phase measurement on the optical field a position measurement of the atom is achieved. We show that it is possible to prepare the atom in a 'contractive state' which beats the standard quantum limit for position measurements.

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Chabaud, Ulysse, Damian Markham e Adel Sohbi. "Quantum machine learning with adaptive linear optics". Quantum 5 (5 luglio 2021): 496. http://dx.doi.org/10.22331/q-2021-07-05-496.

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We study supervised learning algorithms in which a quantum device is used to perform a computational subroutine – either for prediction via probability estimation, or to compute a kernel via estimation of quantum states overlap. We design implementations of these quantum subroutines using Boson Sampling architectures in linear optics, supplemented by adaptive measurements. We then challenge these quantum algorithms by deriving classical simulation algorithms for the tasks of output probability estimation and overlap estimation. We obtain different classical simulability regimes for these two computational tasks in terms of the number of adaptive measurements and input photons. In both cases, our results set explicit limits to the range of parameters for which a quantum advantage can be envisaged with adaptive linear optics compared to classical machine learning algorithms: we show that the number of input photons and the number of adaptive measurements cannot be simultaneously small compared to the number of modes. Interestingly, our analysis leaves open the possibility of a near-term quantum advantage with a single adaptive measurement.

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Molotkov, S. N. "Homodyne detection in quantum optics: deterministic extractors and quantum random number generators on ‘vacuum fluctuations’". Laser Physics 32, n. 5 (7 aprile 2022): 055202. http://dx.doi.org/10.1088/1555-6611/ac5ccc.

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Abstract Quantum random number generators with a continuous variable are considered based on a primary randomness of the outcomes of homodyne measurements of a coherent state. A deterministic method of extraction of truly random 0 and 1 from the primary sequence of measurements of the quadrature of the field in homodyne detection is considered. The method, in the case of independence of successive measurement outcomes, in the asymptotic limit of long sequences, allows us to extract with a polynomial complexity all the true randomness contained in the primary sequence. The method does not require knowledge of the probability distribution function of the primary random sequence, and also does not require additional randomness in the extraction of random 0 and 1. The approach with deterministic randomness extractors, unlike other methods, contains fewer assumptions and conditions that need to be satisfied in the experimental implementation of such generators, and is significantly more effective and simple in experimental implementation. The fundamental limitations dictated by nature for achieving statistical independence of successive measurement outcomes are also considered. The statistical independence of the measurement outcomes is the equivalent of true randomness, in the sense that is possible in the case of the independence of the measurement outcomes, provably, with deterministic extractor, to extract a ‘truly random sequence of 0 and 1’. It is shown that in the asymptotic limit it is possible to extract all the true randomness contained in the outcomes of physical measurements.

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Krotkov, Robert. "Quantum Optics, Experimental Gravitation, and Measurement Theory". American Journal of Physics 53, n. 8 (agosto 1985): 795–96. http://dx.doi.org/10.1119/1.14327.

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KOASHI, Masato. "Recent Progress in Quantum Optics. Quantum Cryptography and Measurement of Quantum States." Review of Laser Engineering 28, n. 10 (2000): 677–81. http://dx.doi.org/10.2184/lsj.28.677.

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Castro Santis, Ricardo. "Quantum stochastic dynamics in multi-photon optics". Infinite Dimensional Analysis, Quantum Probability and Related Topics 17, n. 01 (marzo 2014): 1450007. http://dx.doi.org/10.1142/s0219025714500076.

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Multi-photon models are theoretically and experimentally important because in them quantum properly phenomena are verified; as well as squeezed light and quantum entanglement also play a relevant role in quantum information and quantum communication (see Refs. 18–20).In this paper we study a generic model of a multi-photon system with an arbitrary number of pumping and subharmonics fields. This model includes measurement on the system, as could be direct or homodyne detection and we demonstrate the existence of dynamics in the context of Continuous Measurement Theory of Open Quantum Systems (see Refs. 1–11) using Quantum Stochastic Differential Equations with unbounded coefficients (see Refs. 10–15).

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Chen, Sixin, Taxue Ma, Qian Yu, Pengcheng Chen, Xinzhe Yang, Xuewei Wu, Hai Sang et al. "A perspective on the manipulation of orbital angular momentum states in nonlinear optics". Applied Physics Letters 122, n. 4 (23 gennaio 2023): 040503. http://dx.doi.org/10.1063/5.0135224.

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Orbital angular momentum (OAM) of light has been widely investigated in optical manipulation, optical communications, optical storage, and precision measurement. In recent years, the studies of OAM are expanded to nonlinear and quantum optics, paving a way to high-quality nonlinear imaging, high-capacity quantum communication, and many other promising applications. In this Perspective, we first summarize the fundamental research on OAM in nonlinear optics. Then, we introduce its recent applications in nonlinear imaging (including nonlinear spiral imaging and OAM-multiplexing nonlinear holography) and high-dimensional quantum entanglement. In particular, we highlight the manipulations of OAM through various functional nonlinear photonic crystals. Finally, we discuss the further developments of OAM-based nonlinear and quantum techniques in the near future.

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Tesi sul tema "Quantum optics Measurement"

Cooper, Merlin Frederick Wilmot. "Measurement and manipulation of quantum states of travelling light fields". Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:79164748-ebb3-48e2-b4d4-1a4766d29217.

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This thesis is concerned with the generation of non-classical quantum states of light, the photon-level manipulation of quantum states and the accurate tomography of both quantum states and quantum processes. In optics, quantum information can be encoded and processed in both discrete and continuous variables. Hybrid approaches combining for example homodyne detection with conditional state preparation and manipulation are gaining increasing prominence. The development and characterization of a time-domain balanced homodyne detector (BHD) is presented. The detector has a bandwidth of 80 MHz, a signal-to-noise ratio of 14.5 dB and an efficiency of 86% making it well-suited to pulse-to-pulse measurement of quantum optical states. The BHD is employed to perform quantum state tomography (QST) of non-classical multi-photon Fock states generated by spontaneous parametric down-conversion. A detailed investigation of the mode-matching between the local oscillator used for homodyne detection and the generated Fock states is presented. The one-, two- and three-photon Fock states are reconstructed with a combined preparation and detection efficiency exceeding 50%. Fock states have a number of applications in quantum state engineering, where non-classical ancilla states and conditional measurements enable photon-level manipulation of quantum states. Fock state filtration (FSF) is investigated - an example of a post-selected beam splitter which is a basic building block for many quantum state engineering protocols. A model is developed incorporating the effect of experimental imperfections. An experimental implementation of a Fock state filter is fully characterized by means of coherent-state quantum process tomography (QPT). The reconstructed process is found to be consistent with the model. The filter preferentially removes the single-photon component from an arbitrary input quantum state. Calibration of optical detectors in the quantum regime is discussed. Quantum detector tomography (QDT) is reviewed and contrasted with a new technique for performing QST with a calibrated detector known as the fitting of data patterns (FDP). The first experimental characterization of a BHD is performed by probing the detector with phase-averaged coherent states. The FDP method is shown to be applicable to the estimation of quantum processes, where a detector response is not assumed - thus demonstrating the versatility of the FDP approach as a new method in the quantum tomography toolbox.

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Pregnell, Kenneth Lyell, e n/a. "Retrodictive Quantum State Engineering". Griffith University. School of Science, 2004. http://www4.gu.edu.au:8080/adt-root/public/adt-QGU20041029.134933.

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This thesis is concerned with retrodiction and measurement in quantum optics. The latter of these two concepts is studied in particular form with a general optical multiport device, consisting of an arbitrary array of beam-splitters and phase-shifters. I show how such an apparatus generalizes the original projection synthesis technique, introduced as an in principle technique to measure the canonical phase distribution. Just as for the original projection synthesis, it is found that such a generalised device can synthesize any general projection onto a state in a finite dimensional Hilbert space. One of the important findings of this thesis is that, unlike the original projection synthesis technique, the general apparatus described here only requires a classical, that is a coherent, reference field at the input of the device. Such an apparatus lends itself much more readily to practical implementation and would find applications in measurement and predictive state engineering. If we relax the above condition to allow for just a single non-classical reference field, we show that the apparatus is capable of producing a single-shot measure of canonical phase. That is, the apparatus can project onto any one of an arbitrarily large subset of phase eigenstates, with a probability proportional to the overlap of the phase state and the input field. Unlike the original projection synthesis proposal, this proposal requires a binomial reference state as opposed to a reciprocal binomial state. We find that such a reference state can be obtained, to an excellent approximation, from a suitably squeezed state. The analysis of these measurement apparatuses is performed in the less usual, but completely rigorous, retrodictive formalism of quantum mechanics.

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Kozlowski, Wojciech. "Competition between weak quantum measurement and many-body dynamics in ultracold bosonic gases". Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:8da45dd9-27f9-42b6-8bae-8001d0154966.

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Trapping ultracold atoms in optical lattices enabled the study of strongly correlated phenomena in an environment that is far more controllable and tunable than what was possible in condensed matter. Here, we consider coupling these systems to quantised light where the quantum nature of both the optical and matter fields play equally important roles in order to push the boundaries of what is possible in ultracold atomic systems. We show that light can serve as a nondestructive probe of the quantum state of matter. By considering a global measurement we show that it is possible to distinguish a highly delocalised phase like a superfluid from the Bose glass and Mott insulator. We also demonstrate that light scattering reveals not only density correlations, but also matter-field interference. By taking into account the effect of measurement backaction we show that the measurement can efficiently compete with the local atomic dynamics of the quantum gas. This can generate long-range correlations and entanglement which in turn leads to macroscopic multimode oscillations across the whole lattice when the measurement is weak and correlated tunnelling, as well as selective suppression and enhancement of dynamical processes beyond the projective limit of the quantum Zeno effect in the strong measurement regime. We also consider quantum measurement backaction due to the measurement of matter-phase-related variables such as global phase coherence. We show how this unconventional approach opens up new opportunities to affect system evolution and demonstrate how this can lead to a new class of measurement projections thus extending the measurement postulate for the case of strong competition with the system's own evolution.

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Elouard, Cyril. "Thermodynamics of quantum open systems : applications in quantum optics and optomechanics". Thesis, Université Grenoble Alpes (ComUE), 2017. http://www.theses.fr/2017GREAY046/document.

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La thermodynamique a été développée au XIXe siècle pour décrire la physique des moteurs et autres machines thermiques macroscopiques. Depuis lors, le progrès des nanotechnologies a rendu nécessaire d'étendre ces lois, initialement pensées pour des systèmes classiques, aux systèmes obéissant à la mécanique quantique. Durant cette thèse, j'ai mis en place un formalisme pour étudier la thermodynamique stochastique des systèmes quantiques, dans lequel la mesure quantique occupe une place centrale: à l'instar du bain thermique de la thermodynamique statistique classique, la mesure est ici la source première d'aléatoire dans la dynamique. Dans un premier temps, j'ai étudié la mesure projective comme une transformation thermodynamique à part entière. J'ai montré que la mesure cause un changement incontrôlé de l'énergie du système quantique étudié, que j'ai appelé chaleur quantique, ainsi qu'une production d'entropie. Comme application de ces concepts, j'ai proposé un moteur qui extrait du travail à partir des fluctuations quantiques induites par la mesure. Ensuite, j'ai étudié les mesures généralisées, ce qui a permis de décrire des systèmes quantiques ouverts. J'ai défini les notions de travail, de chaleur, et de production d'entropie pour une réalisation unique d'une transformation thermodynamique, et retrouvé que ces quantités obéissent à des théorèmes de fluctuation. Ce formalisme m'a permis d'analyser le comportement thermodynamique de la situation canonique de l'optique quantique : un atome à deux niveaux en couplé à un laser et au vide électromagnétique. Enfin, j'ai étudié une plate-forme prometteuse pour tester la thermodynamique d'un Qubit : un système hybride optomécanique.Le formalisme développé dans cette thèse peut être d'un grand intérêt pour la communauté de thermodynamique quantique car il permet de caractériser les performances des machines thermiques quantiques et de les comparer à leurs analogues classiques. En outre, en caractérisant la mesure quantique comme un processus thermodynamique, il ouvre la voie à de nouveaux types de machines thermiques, exploitant d'une manière inédite les spécificités du monde quantique
Thermodynamics was developed in the XIXth century to provide a physical description to engines and other macroscopic thermal machines. Since then, progress in nanotechnologies urged to extend these formalism, initially designed for classical systems, to the quantum world. During this thesis, I have built a formalism to study the stochastic thermodynamics of quantum systems, in which quantum measurement plays a central role : like the thermal reservoir of standard stochastic thermodynamics, it is the primary source of randomness in the system's dynamics. I first studied projective measurement as a thermodynamic process. I evidenced that measurement is responsible for an uncontroled variation of the system's energy that I called quantum heat, and also a production of entropy. As a proof of concept, I proposed an engine extracting work from the measurement-induced quantum fluctuations. Then, I extended this formalism to generalized measurements, which allowed to describe open quantum systems (i.e. in contact with reservoirs). I defined work, heat and entropy production for single realizations of thermodynamic protocols, and retrieved that these quantities obey fluctuation theorems. I applied this formalism to the canonical situation of quantum optics, i.e. a Qubit coupled to a laser and a the vacuum. Finally, I studied a promising platform to test Qubit's thermodynamics: a hybrid optomechanical system.The formalism developed in this thesis could be of interest for the quantum thermodynamics community as it enables to characterize quantum heat engines and compare their performances to their classical analogs. Furthermore, as it sets quantum measurement as a thermodynamic process, it pave the ways to a new kind of thermodynamic machines, exploiting the specificities of quantum realm in an unprecedented way

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Buchler, Benjamin Caird. "Electro-optic control of quantum measurements". View thesis entry in Australian Digital Theses Program, 2001. http://thesis.anu.edu.au/public/adt-ANU20020527.131758/index.html.

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Webb, James Engineering &amp Information Technology Australian Defence Force Academy UNSW. "The measurement, creation and manipulation of quantum optical states via photodetection". Awarded by:University of New South Wales - Australian Defence Force Academy. Engineering & Information Technology, 2009. http://handle.unsw.edu.au/1959.4/43686.

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In this thesis, we demonstrate an array of photodetection theory and techniques bridging the traditional discrete and continuous variable experimental domains. In quantum optics, the creation and measurement of states of light are intertwined and we present experimental architectures considering both aspects. We describe the measurement of mean photon numbers at optical sideband frequencies using homodyne detection. We use our technique to provide a direct comparison to photon-counting measurements and observe that our technique exhibits superior speed, dynamic range and mode selectivity compared to photon counters. Our analysis also rejects a semiclassical description of the vacuum state, with our observations supporting the quantum mechanical model. We create a new means of describing the detection ???signatures??? of multi-port networks of non-photon-number discriminating detectors. Our model includes the practical effects of loss and dark counts. We use this model to analyse the performance of the loopand balanced- time-division-multiplexed detector architectures in a projective measurement role. Our analysis leads us to describe a prescriptive recipe for the optimisation of each architecture. In light of contemporary technology, we conclude the balanced TDM detector is the better architecture. Our analysis is then extended to the tomographic reconstruction of an unknown optical state using multi-port photon-counting networks. Our new approach is successfully applied to the reconstruction of the photon statistics of weak coherent states and demonstrates reduced error and sensitivity to experimental parameter variations than established techniques. We report the development of a source of quadrature squeezed vacuum at 1550 nm, and characterise the squeezing observed at the first 3 free spectral ranges of the downconversion cavity. This is then used as a source of frequency-entangled photons for a projective photon subtraction operation described by our earlier theory. We propose a new hybrid time/frequency domain approach to homodyne detection and illustrate its application in characterising the prepared state. Our output state has a statistically significant single photon contribution and permits future experimentation in frequency basis quantum information.

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Folland, Thomas. "Frequency control of terahertz quantum cascade lasers : theory and measurement". Thesis, University of Manchester, 2017. https://www.research.manchester.ac.uk/portal/en/theses/frequency-control-of-terahertz-quantum-cascade-lasers-theory-and-measurement(d4c55769-f053-4b79-aed3-e2fec575adde).html.

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Terahertz (THz) technology stands to solve a number of problems in everyday life, from next generation wireless communication to spectroscopic identification and imaging. However it is technically challenging to make a high power, compact source for terahertz radiation. The Quantum Cascade Laser (QCL), which produces gain at THz frequencies by exploiting inter-sub-band transitions in quantum wells, offers one solution to this problem. However controlling and detecting the emission from such sources remains a major challenge. This thesis investigates the theory and measurement of emission frequencies from aperiodic lattice THz QCLs. Crucially, realising both frequency control and detection provides a complete system for coherent THz characterisation of devices at precise, user defined frequencies. The author starts by studying the emission frequencies and threshold of discretely tuned aperiodic lattice lasers. This is achieved using a numerical transfer matrix method (TMM), which allows the calculation of the aperiodic lattice threshold spectrum for the first time. Calculations reveal that the low threshold modes of aperiodic lattice lasers form at peaks in the electromagnetic density of modes. This shows that lasing in aperiodic lattices arises from slow light propagation induced by multiple photonic band gaps, leading to both band edge and defect laser modes. Frequency selective lasing is maintained even under the influence of external facet feedback, albeit at the cost of precise knowledge of the mode frequency. Importantly this framework allows the understanding of essentially any aperiodic lattice laser system. Most significantly, the TMM is exploited in order to understand how graphene can be used to control a THz laser. Graphene interacts strongly with THz waves, and can be easily integrated with semiconductor structures such as lasers and waveguides. Here, numerical calculations reveal that graphene can be introduced into the waveguide of a THz QCL, generating electrically tunable THz surface plasmons. Such surface plasmons couple into an aperiodic lattice to change the scattering strength of each individual grating element. The TMM reveals that this change in scattering strength controls the modal selectivity of an aperiodic lattice THz QCL. This hypothesis successfully explains both earlier experiments and those performed by the author. Crucially, this model was central to a publication in the journal Science. Finally, this thesis demonstrates a novel coherent detection system for the characterisation of THz QCL emission. The technique exploits non-linear up-conversion of THz waves to a telecoms frequency side-band, a process shown to be sensitive to THz waveguide dispersion. By mixing the up-converted THz wave with a near infra-red local oscillator laser, coherent detection of QCL emission using all fibre coupled components is demonstrated for the first time. This measurement allows for the characterisation of laser emission with high frequency and temporal resolution. Specifically sub-microsecond pulses of THz emission and transients can be detected. When taken as a whole, the work of this thesis constitutes a major step towards realising cost effective THz characterisation and spectroscopy using QCLs.

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Arzani, Francesco. "Measurement based quantum information with optical frequency combs". Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEE005/document.

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Ce manuscrit porte sur l’étude théorique de techniques expérimentales récemment développées pour réaliser des protocoles d’information quantique en variables continues. Les états Gaussiens multi-modes produits par conversion paramétrique de peignes de fréquences optiques jouent un rôle centrale dans ce travail. Ce phénomène permet de générer de façon déterministe un grand nombre d’états Gaussiens de la lumière. L’état de sortie peut ensuite être de-Gaussifié par soustraction ou addition d’un photon dans une superposition cohérente de modes du champ, puis mesuré par détection homodyne. La thèse est organisée en trois projets principaux. Le premier concerne l’optimisation du spectre du laser de pompe pour manipuler l’état de sortie de la conversion paramétrique. Nous avons développé les outils mathématiques pour traiter des profils spectraux avec amplitude et phase spectrales arbitraires. On a ensuite utilisé un algorithme d’optimisation pour trouver les spectres maximisant des différentes propriétés de l’état de sortie. Une importance particulière est donnée à la production d’"états cluster" en variables continues. Les optimisations ont été développées pour prendre en compte les limitations expérimentales pour assurer la faisabilité des forme spectrales dans les expériences. Dans le deuxième projet nous avons étudié comment les états non-Gaussiens obtenus par soustraction d’un photon d’un état comprimé peuvent être utilisés pour le calcul quantique. Nous proposons un protocole inspiré par le paradigme de "calcul quantique basé sur la mesure" qui combine l’état de-Gaussifié et la mesure homodyne pour approximer des opérateurs unitaires non-Gaussiens. On montre que les mêmes résultats peuvent être obtenus avec des mesure projectives sur des états de photon unique. Finalement, le troisième projet porte sur le partage de secret quantique ("quantum secret sharing"). Dans les protocoles de partage de secret quantique un donneur veut distribuer de l’information codée dans un système quantique à plusieurs joueurs d’une façon qui oblige des sous-ensembles de joueurs à collaborer s’ils veulent retrouver l’information originale. Nous avons développé un protocole qui peut être transféré aux expériences de notre groupe et nous avons participé à la formulation d’une preuve de concept expérimentale. À partir de cela, nous avons dérivé des résultats généraux sur le partage et la reconstruction d’états arbitraires de la lumière en utilisant des ressources Gaussiennes
The present manuscript reports theoretical investigations about the use of recently developed experimental techniques in the realization of quantum information protocols with continuous variables. The focus of the work is on the multi-mode Gaussian states produced by spontaneous parametric down-conversion of optical frequency combs. Such setup allows to deterministicallyengineer many different Gaussian states of light. The output state can be de-Gaussified subtracting or adding a photon coherently on a superposition of modes and finally measured with pulse-shaped and wavelength-multiplexed homodyne detection. The thesis encompasses three projects. The first concerns the optimization of the spectrum of the pump laser field to engineer the Gaussian output state. We developed mathematical techniques to treat spectral profiles with arbitrary amplitude and spectral phase. We thenran an optimization algorithm to find the spectra maximizing several interesting properties of the state of the down-converted field. A particular emphasis was put on the production of continuous-variable cluster states. The optimizations were developed in such a way as to ensure the experimental feasibility of the optimized pump spectra. In the second project we studied how the non-Gaussian states produced subtracting a photon from a squeezed state can be used for quantum computation. We propose a protocol inspired by the measurement-based paradigm for quantum computation combining the photon subtracted states and homodyne detectionto approximate unitary non-Gaussian operations. We show that the same results can be obtained with projective measurements onsingle-photon states. Finally, the third project deals with quantum secret sharing. In quantum secret sharing schemes a dealer wants to share information encoded in some quantum system with a group of players in such a way that subsets of players need to collaborate if they want to retrieve the information. We devised a secret sharing protocol that could be mapped to the experimental setups developed in our group and participated in the formulation of an experimental proof of principle of such protocol. Starting from this we derived general results for sharing and reconstructing arbitrary quantum states using Gaussian resources

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Thomas-Peter, Nicholas. "Quantum enhanced precision measurement and information processing with integrated photonics". Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:7bd47582-d32f-4d07-9e90-4978c32cf14e.

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Photons have proven to be an effective test-bed for the fundamental concepts and elements of quantum-enhanced technologies. As systems become increasingly complex, however, practical considerations make the traditional approach of bulk optics and free-space propagation progressively more difficult. The major obstacles are the physical space necessary to realise and operate such a complex system, its stability, and maintaining low losses. In order to address these issues, quantum optical technologies can take a cue from their classical counterparts and look towards an integrated architecture to provide miniaturisation, greatly enhanced stability, less alignment, and low loss interfaces between different system components. In this thesis the feasibility of chip-based waveguides as a platform for metrology and information processing will be explored. In Part I, the necessary criteria for a metrology system to out-perform its classical counterpart will be investigated. It will be found that loss is a major barrier to this aim and, critically, that it is unlikely to have been achieved to date by any experiment which consumes resources of a fixed photon number. The issue of loss will be addressed by developing a scalable heralded source of a class of entangled photonic states which are both robust to losses and practically feasible to prepare. A novel tomographic technique will be developed to characterize these states and it will be explicitly demonstrated how it is possible to beat some bounds on classical performance without being able to out-perform a comparable classical system. Finally, a proof of principle demonstration of a waveguide-based interferometer with an integrated phase-shifter will be undertaken. It will be shown that the device preserves quantum interference, making it suitable for use in quantum-enhanced metrology applications. In Part II, integrated optics in the context of information processing will be discussed. First, a novel characterization technique will be developed which enables the behaviour of complex circuits to be predicted. The technique is independent of loss in the device being characterized. A method of simulating these circuits will be outlined that takes advantage of the computational speed-up available from parallelisation and sparse matrix operations. A key increase in complexity for integrated photonic systems will be demonstrated by showing quantum interference of three photons from two separate sources in eight spatial modes. The resulting interference has a visibility which beats all possible classical interference visibilities for similar circuits. Finally, a fully integrated waveguide-coupled photon-number-resolving detector will be developed and demonstrated. This proof of concept demonstration will show good resolution of different photon number events. The device will be modelled and routes to high efficiency operation will be explored.

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Mazzucchi, Gabriel. "Conditional many-body dynamics and quantum control of ultracold fermions and bosons in optical lattices coupled to quantized light". Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:6c6eddac-41de-476d-851e-6630907965e6.

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We study the atom-light interaction in the fully quantum regime, with the focus on off-resonant light scattering into a cavity from ultracold atoms trapped in an optical lattice. Because of the global coupling between the atoms and the light modes, observing the photons leaking from the cavity allows the quantum nondemolition (QND) measurement of quantum correlations of the atomic ensemble, distinguishing between different quantum states. Moreover, the detection of the photons perturbs the quantum state of the atoms via the so-called measurement backaction. This effect constitutes an unusual additional dynamical source in a many-body strongly correlated system and it is able to efficiently compete with its intrinsic short-range dynamics. This competition becomes possible due to the ability to change the spatial profile of a global measurement at a microscopic scale comparable to the lattice period, without the need of single site addressing. We demonstrate nontrivial dynamical effects such as large-scale multimode oscillations, breakup and protection of strongly interacting fermion pairs. We show that measurement backaction can be exploited for realizing quantum states with spatial modulations of the density and magnetization, thus overcoming usual requirement for a strong interatomic interactions. We propose detection schemes for implementing antiferromagnetic states and density waves and we demonstrate that such long-range correlations cannot be realized with local addressing. Finally, we describe how to stabilize these emerging phases with the aid of quantum feedback. Such a quantum optical approach introduces into many-body physics novel processes, objects, and methods of quantum engineering, including the design of many-body entangled environments for open systems and it is easily extendable to other systems promising for quantum technologies.

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Libri sul tema "Quantum optics Measurement"

Tombesi, P., e D. F. Walls. Quantum measurements in optics. New York: Springer Science, 1992.

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International Workshop on Quantum Communications and Measurement (1994 Nottingham, England). Quantum communications and measurement. New York: Plenum Press, 1995.

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Tombesi, P., e O. Hirota. Quantum communication, computing, and measurement 3. New York: Kluwer Academic, 2002.

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International Conference on Quantum Communication, Measurement, and Computing (4th 1998 Northwestern University, Evanston, Ill.). Quantum communication, computing and measurement 2. New York: Kluwer Academic/Plenum Publishers, 2000.

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International Conference on Quantum Communication, Measurement, and Computing (4th 1998 Northwestern University). Quantum communication, computing and measurement 2. New York: Kluwer Academic, 2002.

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P, Belavkin V., Hirota O e Hudson R. L. 1960-, a cura di. Quantum communications and measurement: [proceedings of an International Workshop on Quantum Communications and Measurement, held July 11-16, 1994, in Nottingham, England]. New York: Plenum Press, 1995.

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P, Tombesi, Hirota O. 1948- e International Conference on Quantum Communication, Measurement, and Computing (5th : 2000 : Capri, Italy), a cura di. Quantum communication, computing, and measurement 3. New York: Kluwer Academic/Plenum Publishers, 2001.

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International, Conference on Quantum Communication Measurement and Computing (8th 2006 Tsukuba-shi Japan). Proceedings of the 8th International Conference on Quantum Communication, Measurement and Computing. [Tokyo]: National Institute of Information and Communications Technology, 2007.

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International Conference on Quantum Communication, Measurement, and Computing (8th 2006 Tsukuba-shi, Japan). Proceedings of the 8th International Conference on Quantum Communication, Measurement and Computing. Tokyo]: National Institute of Information and Communications Technology, 2007.

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Capitoli di libri sul tema "Quantum optics Measurement"

Walls, D. F., e G. J. Milburn. "Quantum Coherence and Measurement Theory". In Quantum Optics, 297–314. Berlin, Heidelberg: Springer Berlin Heidelberg, 1994. http://dx.doi.org/10.1007/978-3-642-79504-6_16.

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Stenholm, Stig. "Measurement Aspects of Quantum Optics". In Quantum Chaos — Quantum Measurement, 231–40. Dordrecht: Springer Netherlands, 1992. http://dx.doi.org/10.1007/978-94-015-7979-7_18.

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Peřina, Jan, Zdeněk Hradil e Branislav Jurčo. "Quantum theory of measurement". In Quantum Optics and Fundamentals of Physics, 54–115. Dordrecht: Springer Netherlands, 1994. http://dx.doi.org/10.1007/978-94-011-0932-1_3.

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Garraway, B. M., e P. L. Knight. "Stochastic Simulations of Dissipation in Quantum Optics: Quantum Superpositions". In Quantum Communications and Measurement, 463–77. Boston, MA: Springer US, 1995. http://dx.doi.org/10.1007/978-1-4899-1391-3_46.

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Brecha, R. J., e H. Walther. "The Quantum Measurement Process and the One-Atom Maser". In Quantum Measurements in Optics, 93–104. Boston, MA: Springer US, 1992. http://dx.doi.org/10.1007/978-1-4615-3386-3_8.

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Yamamoto, Yoshihisa, Wayne H. Richardson e Susumu Machida. "Quantum Mechanical Watch-Dog Effect and Measurement-Induced State Reduction in a Semiconductor Laser". In Quantum Measurements in Optics, 65–84. Boston, MA: Springer US, 1992. http://dx.doi.org/10.1007/978-1-4615-3386-3_6.

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Grangier, Philippe, Jean-François Roch e Gérard Roger. "Quantum Non-Demolition Measurement of an Optical Intensity in a Three-Level Atomic Non-Linear System". In Quantum Measurements in Optics, 85–92. Boston, MA: Springer US, 1992. http://dx.doi.org/10.1007/978-1-4615-3386-3_7.

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Davidovich, Luiz. "Decoherence and Quantum-State Measurement in Quantum Optics". In Decoherence and Entropy in Complex Systems, 268–86. Berlin, Heidelberg: Springer Berlin Heidelberg, 2003. http://dx.doi.org/10.1007/978-3-540-40968-7_19.

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Herkommer, A. M., H. J. Carmichael e W. P. Schleich. "Localization of Atoms by Homodyne Measurement". In Coherence and Quantum Optics VII, 543–44. Boston, MA: Springer US, 1996. http://dx.doi.org/10.1007/978-1-4757-9742-8_144.

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Milburn, G. J., e B. C. Sanders. "Preparation of Nonclassical States by Conditional Measurement". In Coherence and Quantum Optics VI, 753–57. Boston, MA: Springer US, 1990. http://dx.doi.org/10.1007/978-1-4613-0847-8_138.

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Atti di convegni sul tema "Quantum optics Measurement"

Boyd, Robert W. "Quantum Nonlinear Optics: Nonlinear Optics Meets the Quantum World". In Quantum Information and Measurement. Washington, D.C.: OSA, 2014. http://dx.doi.org/10.1364/qim.2014.qtu2a.1.

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Roussel, Benjamin, Clément Cabart e Pascal Degiovanni. "Quantum signal processing for electron quantum optics". In Quantum Information and Measurement. Washington, D.C.: OSA, 2017. http://dx.doi.org/10.1364/qim.2017.qw5a.1.

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Xiang, Guoyong. "Quantum collective measurement". In Quantum and Nonlinear Optics VII, a cura di Kebin Shi, Chuan-Feng Li e Dai-Sik Kim. SPIE, 2020. http://dx.doi.org/10.1117/12.2575258.

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Zadeh, Iman Esmaeil, Ali Elshaari, Johannes W. N. Los, Ronan Gourgues, Julien Zichi, Sander Dorenbos, Michael E. Reimer et al. "Scalable quantum optics with nanowires". In Quantum Information and Measurement. Washington, D.C.: OSA, 2019. http://dx.doi.org/10.1364/qim.2019.f4a.5.

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Lipson, Michal. "Silicon Photonic Platform for Quantum Optics". In Quantum Information and Measurement. Washington, D.C.: OSA, 2013. http://dx.doi.org/10.1364/qim.2013.w5a.1.

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Aaronson, Scott, e Alex Arkhipov. "The Computational Complexity of Linear Optics". In Quantum Information and Measurement. Washington, D.C.: OSA, 2014. http://dx.doi.org/10.1364/qim.2014.qth1a.2.

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Yokoyama, Shota, Nicola Dalla Pozza, Takahiro Serikawa, Katanya B. Kuntz, Trevor A. Wheatley, Daoyi Dong, Elanor H. Huntington e Hidehiro Yonezawa. "The Quantum Entanglement of Measurement". In Frontiers in Optics. Washington, D.C.: OSA, 2017. http://dx.doi.org/10.1364/fio.2017.fth3e.6.

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Hayat, Alex, Pavel Ginzburg, David Neiman, Serge Rosenblum e Meir Orenstein. "Photon-Hole Quantum Nondemolition Measurement". In Frontiers in Optics. Washington, D.C.: OSA, 2008. http://dx.doi.org/10.1364/fio.2008.fmh7.

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Gaeta, Alex. "Nonlinear Optics at the Few-Photon Level". In Quantum Information and Measurement. Washington, D.C.: OSA, 2013. http://dx.doi.org/10.1364/qim.2013.th1.2.

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Chakhmakhchyan, Levon, e Nicolas J. Cerf. "Simulating Universal Gaussian Circuits with Linear Optics". In Quantum Information and Measurement. Washington, D.C.: OSA, 2019. http://dx.doi.org/10.1364/qim.2019.f4b.4.

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Rapporti di organizzazioni sul tema "Quantum optics Measurement"

Pfeifer, K. B., e M. W. Jenkins. A fiber optic test system for quantum efficiency measurements. Office of Scientific and Technical Information (OSTI), maggio 1989. http://dx.doi.org/10.2172/5988907.

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