Articles de revues : « Blue- detuned optical lattices »

1

Guo, J., et J. Cooper. « Probe-transmission spectrum of a blue-detuned optical lattice ». Physical Review A 52, n^o 3 (1 septembre 1995) : R1819—R1822. http://dx.doi.org/10.1103/physreva.52.r1819.

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Krasnov, I. V. « Ultracold plasma in blue-detuned optical molasses ». Physics Letters A 372, n^o 17 (avril 2008) : 3118–23. http://dx.doi.org/10.1016/j.physleta.2008.01.021.

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Winoto, S., Marshall DePue, Nathan Bramall et David Weiss. « Laser cooling at high density in deep far-detuned optical lattices ». Physical Review A 59, n^o 1 (janvier 1999) : R19—R22. http://dx.doi.org/10.1103/physreva.59.r19.

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Zhang, Li-Wei, Xian-Li Li et Liu Yang. « Optical nonreciprocity with blue-detuned driving in two-cavity optomechanics ». Acta Physica Sinica 68, n^o 17 (2019) : 170701. http://dx.doi.org/10.7498/aps.68.20190205.

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Chen, Zhao, Fan Zhang, Qi Zhang, Juanjuan Ren, He Hao, Xueke Duan, Pengfei Zhang, Tiancai Zhang, Ying Gu et Qihuang Gong. « Blue-detuned optical atom trapping in a compact plasmonic structure ». Photonics Research 5, n^o 5 (21 août 2017) : 436. http://dx.doi.org/10.1364/prj.5.000436.

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Piest, B., V. Vollenkemper, J. Böhm, A. Herbst et E. M. Rasel. « Red- and blue-detuned magneto-optical trapping with liquid crystal variable retarders ». Review of Scientific Instruments 93, n^o 2 (1 février 2022) : 023202. http://dx.doi.org/10.1063/5.0071619.

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Xu, Peng, Xiaodong He, Jin Wang et Mingsheng Zhan. « Trapping a single atom in a blue detuned optical bottle beam trap ». Optics Letters 35, n^o 13 (21 juin 2010) : 2164. http://dx.doi.org/10.1364/ol.35.002164.

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Ozeri, Roee, Lev Khaykovich et Nir Davidson. « Long spin relaxation times in a single-beam blue-detuned optical trap ». Physical Review A 59, n^o 3 (1 mars 1999) : R1750—R1753. http://dx.doi.org/10.1103/physreva.59.r1750.

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Pechkis, Joseph A., et Fredrik K. Fatemi. « Cold atom guidance in a capillary using blue-detuned, hollow optical modes ». Optics Express 20, n^o 12 (31 mai 2012) : 13409. http://dx.doi.org/10.1364/oe.20.013409.

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Turpin, A., J. Polo, Yu V. Loiko, J. Küber, F. Schmaltz, T. K. Kalkandjiev, V. Ahufinger, G. Birkl et J. Mompart. « Blue-detuned optical ring trap for Bose-Einstein condensates based on conical refraction ». Optics Express 23, n^o 2 (23 janvier 2015) : 1638. http://dx.doi.org/10.1364/oe.23.001638.

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Yu, Haiyu, Zhixiang Mao, Junyi Li, Yuer Ye, Yaling Yin, Yong Xia et Jianping Yin. « Chip-scale molecule trapping by a blue-detuned metasurface hollow beam ». Journal of Optics 22, n^o 4 (24 mars 2020) : 045104. http://dx.doi.org/10.1088/2040-8986/ab7aea.

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Kudo, Tetsuhiro, Hajime Ishihara et Hiroshi Masuhara. « Resonance optical trapping of individual dye-doped polystyrene particles with blue- and red-detuned lasers ». Optics Express 25, n^o 5 (21 février 2017) : 4655. http://dx.doi.org/10.1364/oe.25.004655.

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Mercadé, Laura, Leopoldo L. Martín, Amadeu Griol, Daniel Navarro-Urrios et Alejandro Martínez. « Microwave oscillator and frequency comb in a silicon optomechanical cavity with a full phononic bandgap ». Nanophotonics 9, n^o 11 (31 juillet 2020) : 3535–44. http://dx.doi.org/10.1515/nanoph-2020-0148.

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AbstractCavity optomechanics has recently emerged as a new paradigm enabling the manipulation of mechanical motion via optical fields tightly confined in deformable cavities. When driving an optomechanical (OM) crystal cavity with a laser blue-detuned with respect to the optical resonance, the mechanical motion is amplified, ultimately resulting in phonon lasing at MHz and even GHz frequencies. In this work, we show that a silicon OM crystal cavity performs as an OM microwave oscillator when pumped above the threshold for self-sustained OM oscillations. To this end, we use an OM cavity designed to have a breathing-like mechanical mode at 3.897 GHz in a full phononic bandgap. Our measurements show that the first harmonic of the detected signal displays a phase noise of ≈−100 dBc/Hz at 100 kHz. Stronger blue-detuned driving leads eventually to the formation of an OM frequency comb, whose lines are spaced by the mechanical frequency. We also measure the phase noise for higher-order harmonics and show that, unlike in Brillouin oscillators, the noise is increased as corresponding to classical harmonic mixing. Finally, we present real-time measurements of the comb waveform and show that it can be fitted to a theoretical model recently presented. Our results suggest that silicon OM cavities could be relevant processing elements in microwave photonics and optical RF processing, in particular in disciplines requiring low weight, compactness and fiber interconnection.

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Pan, Deng, Hongxing Xu et F. Javier García de Abajo. « Rotational Doppler cooling and heating ». Science Advances 7, n^o 2 (janvier 2021) : eabd6705. http://dx.doi.org/10.1126/sciadv.abd6705.

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Doppler cooling is a widely used technique to laser cool atoms, molecules, and nanoparticles by exploiting the Doppler shift associated with translational motion. The rotational Doppler effect arising from rotational coordinate transformation should similarly enable optical manipulation of the rotational motion of nanosystems. Here, we show that rotational Doppler cooling and heating (RDC and RDH) effects embody rich and unexplored physics, including an unexpected strong dependence on particle morphology. For geometrically constrained particles, cooling and heating are observed at red- or blue-detuned laser frequencies relative to particle resonances. In contrast, for nanosystems that can be modeled as solid particles, RDH appears close to resonant illumination, while detuned frequencies produce cooling of rotation. We further predict that RDH can lead to optomechanical spontaneous chiral symmetry breaking, where an achiral particle under linearly polarized illumination starts spontaneously rotating. Our results open up new exciting possibilities to control the rotational motion of nanosystems.

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Li, Xiaoxia, Jingyan Li, Xuxin Cheng et Guang-an Li. « Nonreciprocal transmission in a four-mode cavity magnonics system ». Laser Physics Letters 19, n^o 9 (10 août 2022) : 095208. http://dx.doi.org/10.1088/1612-202x/ac85e9.

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Abstract We propose a scheme to create optical nonreciprocal transmission in a double-cavity magnonics system, where one yttrium iron garnet sphere is placed in one of the cavities and a mechanical oscillator is shared by the coupled double microwave cavities. By manipulating the magnon–microwave photon coupling, we reveal the nonreciprocal propagation of electromagnetic fields at microwave frequencies in red and blue-detuned regimes. Furthermore, the nonreciprocal isolation ratio and group delay are analyzed. This scheme can inspire methods for constructing nonreciprocal devices.

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Kai-Jun, Jiang, Li Ke, Wang Jin et Zhan Ming-Sheng. « Optical Guiding of Trapped Atoms by a Blue-Detuned Hollow Laser Beam in the Horizontal Direction ». Chinese Physics Letters 22, n^o 2 (27 janvier 2005) : 324–27. http://dx.doi.org/10.1088/0256-307x/22/2/016.

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Zhou, Xiaodong, Wanxiang Feng, Fei Li et Yugui Yao. « Large magneto-optical effects in hole-doped blue phosphorene and gray arsenene ». Nanoscale 9, n^o 44 (2017) : 17405–14. http://dx.doi.org/10.1039/c7nr05088g.

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Blue phosphorene (BP) and gray arsenene (GA), consisting of phosphorus and arsenic atoms in two-dimensional (2D) low-buckled honeycomb lattices, respectively, have received great interest because of their excellent electronic and optoelectronic performances.

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Sagué, G., A. Baade et A. Rauschenbeutel. « Blue-detuned evanescent field surface traps for neutral atoms based on mode interference in ultrathin optical fibres ». New Journal of Physics 10, n^o 11 (7 novembre 2008) : 113008. http://dx.doi.org/10.1088/1367-2630/10/11/113008.

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He, Xiaodong, Shi Yu, Peng Xu, Jin Wang et Mingsheng Zhan. « Combining red and blue-detuned optical potentials to form a Lamb-Dicke trap for a single neutral atom ». Optics Express 20, n^o 4 (31 janvier 2012) : 3711. http://dx.doi.org/10.1364/oe.20.003711.

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Plewa, Julian, et T. Juestel. « Synthesis and Optical Characterization of Pr³⁺ Doped UV Emitting Luminescent Ceramics ». Materials Science Forum 636-637 (janvier 2010) : 344–47. http://dx.doi.org/10.4028/www.scientific.net/msf.636-637.344.

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UV emitting luminescent materials are of strong interest for UV emitting fluorescent lamps driven by a Hg low-pressure or a by Xe excimer discharge. Pr3+ doped host lattices exhibit efficient UV emission upon deep UV excitation, if the site of the host lattice, where Pr3+ is located, is suitable for this purpose. This work deals with Pr3+ activated VUV ceramic luminophores, i.e. materials, which show efficient luminescence upon 160 nm excitation. As host lattices for the potentially UV emitting Pr3+ ion aluminates and silicates have been studied. All samples were prepared by conventional mix and fire synthesis techniques with metal oxides as starting materials. Firstly, powder samples were annealed between 1000 and 1700 °C and secondly, ceramic samples were repeatedly thermally treated at similar temperatures after pressing. It is demonstrated that translucent ceramics show mainly UV luminescence upon deep UV excitation, while excitation by a blue 450 nm LED results in green to red luminescence with a similar decay time as observed for single crystals.

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Cordoyiannis, George, Marta Lavrič, Vasileios Tzitzios, Maja Trček, Ioannis Lelidis, George Nounesis, Samo Kralj, Jan Thoen et Zdravko Kutnjak. « Experimental Advances in Nanoparticle-Driven Stabilization of Liquid-Crystalline Blue Phases and Twist-Grain Boundary Phases ». Nanomaterials 11, n^o 11 (5 novembre 2021) : 2968. http://dx.doi.org/10.3390/nano11112968.

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Recent advances in experimental studies of nanoparticle-driven stabilization of chiral liquid-crystalline phases are highlighted. The stabilization is achieved via the nanoparticles’ assembly in the defect lattices of the soft liquid-crystalline hosts. This is of significant importance for understanding the interactions of nanoparticles with topological defects and for envisioned technological applications. We demonstrate that blue phases are stabilized and twist-grain boundary phases are induced by dispersing surface-functionalized CdSSe quantum dots, spherical Au nanoparticles, as well as MoS2 nanoplatelets and reduced-graphene oxide nanosheets in chiral liquid crystals. Phase diagrams are shown based on calorimetric and optical measurements. Our findings related to the role of the nanoparticle core composition, size, shape, and surface coating on the stabilization effect are presented, followed by an overview of and comparison with other related studies in the literature. Moreover, the key points of the underlying mechanisms are summarized and prospects in the field are briefly discussed.

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Zakria, M., Taj Muhammad Khan, Abbas Nasir et Arshad Mahmood. « Annealing-induced effects on structural and optical properties of Cd1−xZnxS thin films for optoelectronic applications ». Materials Science-Poland 33, n^o 4 (1 décembre 2015) : 677–84. http://dx.doi.org/10.1515/msp-2015-0096.

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AbstractCd1−xZnxS thin films of variable compositions (x = 0.2, 0.4, 0.6, 0.8) were deposited on glass at room temperature by thermal evaporation process. The prepared samples were annealed at two different temperatures (300 °C, 400 °C) for 1 hour in ambient air. The effects of post-annealing on the structural and optical characteristics were investigated using X-ray diffraction (XRD), spectrophotometry, and Raman spectroscopy (RS) methods. XRD studies suggested that the annealed and as-deposited samples belong to wurtzite structure for all Zn concentrations with a preferential orientation along (002) plane. Spectrophotometry analysis of the samples revealed that the energy band gap decreased with annealing temperature. RS investigated different phonon bands and crystalline phases. Two longitudinal optical phonon modes (1-LO, 2-LO) corresponding to monophase hexagonal structure were observed for all Cd1−xZnxS samples. The observed red-shift and anti-symmetrical nature of the 1-LO phonon mode can be associated with annealing, while the overall blue-shift, except for x ⩽ 0.6, was caused by the structural disorders in periodic Cd atomic sub-lattices and broken translational symmetry. The spectroscopic results were strengthened by the XRD studies and their results are consistent.

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Bafekry, A., C. Stampfl, M. Faraji, B. Mortazavi, M. M. Fadlallah, Chuong V. Nguyen, S. Fazeli et M. Ghergherehchi. « Monoelemental two-dimensional iodinene nanosheets : a first-principles study of the electronic and optical properties ». Journal of Physics D : Applied Physics 55, n^o 13 (31 décembre 2021) : 135104. http://dx.doi.org/10.1088/1361-6463/ac45ad.

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Abstract Very recently, two-dimensional (2D) iodinene, a novel layered and buckled structure has been successfully fabricated (Qian et al 2020 Adv. Mater. 32 2004835). Motivated by this latest experimental accomplishment, for the first time we conduct density functional theory, first-principles calculations to explore the structural, electronic, and optical properties of monolayer, few-layer and bulk iodinene. Unlike the majority of monoelemental 2D lattices, iodinene is predicted to be an intrinsic semiconductor. On the basis of calculations using the generalized gradient approximation of Perdew–Burke–Ernzerhof for the exchange-correlation functional and the Heyd-Scuseria-Ernzerhof (HSE06) functional, it is shown that the electronic bandgap of iodinene decreases with increasing the number of atomic layers. Our HSE06 results reveal that the bandgap of iodinene decreases from 2.08 to 1.28 eV as the number of atomic layers change from one to five, highlighting the finely tunable bandgap. The optical study shows the monolayer has the ability to absorb a wide range of ultraviolet light, more than multilayers and bulk iodinene. As the number of layers increases, the absorption spectra exhibits a blue shift relative to monolayer iodinene. This study confirms the remarkable prospect for the application of iodinene in nanoelectronics and optoelectronics owing to its intrinsic semiconducting nature.

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Piilo, J., et K. A. Suominen. « Optical shielding of cold collisions in blue-detuned near-resonant optical lattices ». Physical Review A 66, n^o 1 (1 juillet 2002). http://dx.doi.org/10.1103/physreva.66.013401.

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Takamoto, M., H. Katori, S. I. Marmo, V. D. Ovsiannikov et V. G. Pal’chikov. « Prospects for Optical Clocks with a Blue-Detuned Lattice ». Physical Review Letters 102, n^o 6 (10 février 2009). http://dx.doi.org/10.1103/physrevlett.102.063002.

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Yu, Deshui, et Frank Vollmer. « Microscale whispering-gallery-mode light sources with lattice-confined atoms ». Scientific Reports 11, n^o 1 (6 juillet 2021). http://dx.doi.org/10.1038/s41598-021-93295-5.

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AbstractMicrolasers, relying on the strong coupling between active particles and optical microcavity, exhibit fundamental differences from conventional lasers, such as multi-threshold/thresholdless behavior and nonclassical photon emission. As light sources, microlasers possess extensive applications in precision measurement, quantum information processing, and biochemical sensing. Here we propose a whispering-gallery-mode microlaser scheme, where ultracold alkaline-earth metal atoms, i.e., gain medium, are tightly confined in a two-color evanescent lattice that is in the ring shape and formed around a microsphere. To suppress the influence of the lattice-induced ac Stark shift on the moderately-narrow-linewidth laser transition, the red-detuned trapping beams operate at a magic wavelength while the wavelength of the blue-detuned trapping beam is set close to the other magic wavelength. The tiny mode volume and high quality factor of the microsphere ensure the strong atom-microcavity coupling in the bad-cavity regime. As a result, both saturation photon and critical atom numbers, which characterize the laser performance, are substantially reduced below unity. We explore the lasing action of the coupled system by using the Monte Carlo approach. Our scheme may be potentially generalized to the microlasers based on the forbidden clock transitions, holding the prospect for microscale active optical clocks in precision measurement and frequency metrology.

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Jarvis, K. N., J. A. Devlin, T. E. Wall, B. E. Sauer et M. R. Tarbutt. « Blue-Detuned Magneto-Optical Trap ». Physical Review Letters 120, n^o 8 (20 février 2018). http://dx.doi.org/10.1103/physrevlett.120.083201.

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Terraciano, Matthew L., Spencer E. Olson et Fredrik K. Fatemi. « Temperature-dependent photon scattering in blue-detuned optical traps ». Physical Review A 84, n^o 2 (3 août 2011). http://dx.doi.org/10.1103/physreva.84.025402.

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Piotrowicz, M. J., M. Lichtman, K. Maller, G. Li, S. Zhang, L. Isenhower et M. Saffman. « Two-dimensional lattice of blue-detuned atom traps using a projected Gaussian beam array ». Physical Review A 88, n^o 1 (24 juillet 2013). http://dx.doi.org/10.1103/physreva.88.013420.

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Ling, Chen, Yaling Yin, Yang Liu, Lin Li et Yong Xia. « Generation of blue-detuned optical storage ring by metasurface and its application in optical trapping of cold molecules ». Chinese Physics B, 7 mai 2022. http://dx.doi.org/10.1088/1674-1056/ac6db0.

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Abstract A scheme of storage of cold molecules with hollow optical ring generated by the metasurface grating is proposed. The characteristics and intensity distribution related to the ring’s structural parameters alongside the fabrication-error tolerance are theoretically studied. The optical potential and dipole force for the ring to trap magnesium monofluoride (MgF) molecules are also calculated. The dynamical behavior of MgF molecules in the storage ring is simulated by a Monte-Carlo method, which shows that the metasurface-based optical storage ring is applicable to trap molecules and can be an interesting platform for the research of ultracold quantum gases and their quantum-state manipulation.

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Friedman, N., L. Khaykovich, R. Ozeri et N. Davidson. « Compression of cold atoms to very high densities in a rotating-beam blue-detuned optical trap ». Physical Review A 61, n^o 3 (3 février 2000). http://dx.doi.org/10.1103/physreva.61.031403.

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Cunningham, Paul D., Aubrey T. Hanbicki, Thomas L. Reinecke, Kathleen M. McCreary et Berend T. Jonker. « Resonant optical Stark effect in monolayer WS2 ». Nature Communications 10, n^o 1 (décembre 2019). http://dx.doi.org/10.1038/s41467-019-13501-x.

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AbstractBreaking the valley degeneracy in monolayer transition metal dichalcogenides through the valley-selective optical Stark effect (OSE) can be exploited for classical and quantum valleytronic operations such as coherent manipulation of valley superposition states. The strong light-matter interactions responsible for the OSE have historically been described by a two-level dressed-atom model, which assumes noninteracting particles. Here we experimentally show that this model, which works well in semiconductors far from resonance, does not apply for excitation near the exciton resonance in monolayer WS2. Instead, we show that an excitonic model of the OSE, which includes many-body Coulomb interactions, is required. We confirm the prediction from this theory that many-body effects between virtual excitons produce a dominant blue-shift for photoexcitation detuned from resonance by less than the exciton binding energy. As such, we suggest that our findings are general to low-dimensional semiconductors that support bound excitons and other many-body Coulomb interactions.

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Ozeri, R., L. Khaykovich et N. Davidson. « Erratum : Long spin relaxation times in a single-beam blue-detuned optical trap [Phys. Rev. A59, R1750 (1999)] ». Physical Review A 65, n^o 6 (12 juin 2002). http://dx.doi.org/10.1103/physreva.65.069903.

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Brooks, Ralph Vincent, Alexander Guttridge, Matthew David Frye, Daniel Keith Ruttley, Stefan Spence, Jeremy M. Hutson et S. L. Cornish. « Feshbach Spectroscopy of Cs Atom Pairs in Optical Tweezers ». New Journal of Physics, 13 octobre 2022. http://dx.doi.org/10.1088/1367-2630/ac99f6.

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Abstract We prepare pairs of $^{133}$Cs atoms in a single optical tweezer and perform Feshbach spectroscopy for collisions of atoms in the states $(f=3, m_f=\pm3)$. We detect enhancements in pair loss using a detection scheme where the optical tweezers are repeatedly subdivided. For atoms in the state $(3,-3)$, we identify resonant features by performing inelastic loss spectroscopy. We carry out coupled-channel scattering calculations and show that at typical experimental temperatures the loss features are mostly centred on zeroes in the scattering length, rather than resonance centres. We measure the number of atoms remaining after a collision, elucidating how the different loss processes are influenced by the tweezer depth. These measurements probe the energy released during an inelastic collision, and thus give information on the states of the collision products. We also identify resonances with atom pairs prepared in the absolute ground state $(f=3, m_f=3)$, where two-body radiative loss is engineered by an excitation laser blue-detuned from the Cs D$_2$ line. These results demonstrate optical tweezers to be a versatile tool to study two-body collisions with number-resolved detection sensitivity.

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Liu, Shikang, Pascal Neveu, Joseph Delpy, Louka Hemmen, Etienne Brion, E. Wu, Fabien Bretenaker et Fabienne Goldfarb. « Birefringence and dichroism effects in the spin noise spectra of a spin-1 system ». New Journal of Physics, 18 novembre 2022. http://dx.doi.org/10.1088/1367-2630/aca428.

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Abstract We perform spin noise spectroscopy experiments in metastable helium atoms at room temperature, with a probe light whose frequency is blue detuned from the D0 line. Both circular birefringence fluctuations (Faraday noise) and linear birefringence fluctuations (ellipticity noise) are explored theoretically and experimentally. In particular, it is shown that in both cases but for different optical detunings, two noise resonances are isolated at the Larmor frequency and at twice the Larmor frequency with a behaviour, which strongly depends on the orientation of the probe field polarization. The simple structure of metastable helium allows us to probe, model and explain the changes in the behavior of these peaks in terms of circular and linear dichroisms and birefringences as well as in terms of spin oscillation modes.

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Chen, Hao, NingNing Yang, Chengzhi Qin, Wenwan Li, Bing Wang, Tianwen Han, Chi Zhang et al. « Real-time observation of frequency Bloch oscillations with fibre loop modulation ». Light : Science & ; Applications 10, n^o 1 (5 mars 2021). http://dx.doi.org/10.1038/s41377-021-00494-w.

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AbstractBloch oscillations (BOs) were initially predicted for electrons in a solid lattice to which a static electric field is applied. The observation of BOs in solids remains challenging due to the collision scattering and barrier tunnelling of electrons. Nevertheless, analogies of electron BOs for photons, acoustic phonons and cold atoms have been experimentally demonstrated in various lattice systems. Recently, BOs in the frequency dimension have been proposed and studied by using an optical micro-resonator, which provides a unique approach to controlling the light frequency. However, the finite resonator lifetime and intrinsic loss hinder the effect from being observed practically. Here, we experimentally demonstrate BOs in a synthetic frequency lattice by employing a fibre-loop circuit with detuned phase modulation. We show that a detuning between the modulation period and the fibre-loop roundtrip time acts as an effective vector potential and hence a constant effective force that can yield BOs in the modulation-induced frequency lattices. With a dispersive Fourier transformation, the pulse spectrum can be mapped into the time dimension, and its transient evolution can be precisely measured. This study offers a promising approach to realising BOs in synthetic dimensions and may find applications in frequency manipulations in optical fibre communication systems.

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Chen, Cheng-Chang, Hsiang-Ting Lin, Shih-Pang Chang, Hao-Chung Kuo, Hsiao-Wen Hung, Kuo-Hsiang Chien, Yu-Choung Chang et M. H. Shih. « Multicolor Emission from Ultraviolet GaN-Based Photonic Quasicrystal Nanopyramid Structure with Semipolar InxGa1−xN/GaN Multiple Quantum Wells ». Nanoscale Research Letters 16, n^o 1 (16 septembre 2021). http://dx.doi.org/10.1186/s11671-021-03576-1.

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AbstractIn this study, we demonstrated large-area high-quality multi-color emission from the 12-fold symmetric GaN photonic quasicrystal nanorod device which was fabricated using the nanoimprint lithography technology and multiple quantum wells regrowth procedure. High-efficiency blue and green color emission wavelengths of 460 and 520 nm from the regrown InxGa1−xN/GaN multiple quantum wells were observed under optical pumping conditions. To confirm the strong coupling between the quantum well emissions and the photonic crystal band-edge resonant modes, the finite-element method was applied to perform a simulation of the 12-fold symmetry photonic quasicrystal lattices.

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Yang, Pengfei, Gang Li, Zhihui Wang, Pengfei Zhang et Tiancai Zhang. « Gate fidelity, dephasing, and “magic” trapping of optically trapped neutral atom ». New Journal of Physics, 8 août 2022. http://dx.doi.org/10.1088/1367-2630/ac87ca.

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Abstract The fidelity of the gate operation and the coherence time of neutral atoms trapped in an optical dipole trap are figures of merit for the applications. The motion of the trapped atom is one of the key factors which influence the gate fidelity and coherence time. However, it has been considered as a classical oscillator in analysis of the coherence time. Here we treat the motion as a quantum oscillator, and the population on the vibrational states of the atom are taken into account in analyzing the gate fidelity and decoherence. We show that the fidelity of a coherent rotation gate between two hyperfine states is dramatically limited by the population distribution on the vibrational states. We also find that the description of the decoherence caused by the previously regarded inhomogeneous dephasing due to the thermal motion of the atom is actually homogeneous in a quantum view. The phase between the two hyperfine states is still preserved on different vibrational states, and the observed interference fringe will recover naturally if the differential frequency shift is stable and the vibrational states do not change. The decoherence due to the fluctuations of the trap laser intensity is also discussed. Both the gate fidelity and coherence time can be dramatically enhanced by cooling the atom into vibrational ground states and/or by using a blue-detuned trap. More importantly, we propose a ``magic'' trapping condition by preparing the atom into specific vibrational states.

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Onishi, Takehiro, Andrew J. Lohn et Nobuhiko P. Kobayashi. « Optical properties and carrier dynamics of ensembles of InP nanowires grown on non-single-crystal platforms ». MRS Proceedings 1178 (2009). http://dx.doi.org/10.1557/proc-1178-aa01-04.

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AbstractOptically active InP nanowires were grown on a quartz substrate covered with a layer (100 nm) of hydrogenated amorphous silicon (a-Si:H) by metalorganic chemical vapor deposition (MOCVD), demonstrating that single-crystal semiconductor nanowires can be formed on non-single-crystal surfaces. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, cathodoluminescence (CL), and photoluminescence (PL) were used to characterize the structural and optical properties of the nanowires. The nanowires on a-Si:H grew in random directions with high density. The XRD suggests that nanowires having either hexagonal-close-packed or face-centered cubic lattices co-exist. The Raman spectrum shows peaks associated with transverse optical (TO) and longitudinal optical (LO) branches of InP. The CL intensity does not vary signi?cantly along the growth direction and appears to be originated from the entire structure of the nanowire when probed at various positions. The CL data suggests that recombination is slow enough to allow the carriers to diffuse the complete length of the nanowires (˜2 m in length) before recombining. The PL spectrum suggested the nanowire had a part that contributes to the observed blue shift while the other part had nearly bulk feature in their structure.

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Yan, Shirun. « On The Validity of the Defect- Induced Negative Thermal Quenching of Eu²⁺-Doped Phosphors ». ECS Journal of Solid State Science and Technology, 29 décembre 2022. http://dx.doi.org/10.1149/2162-8777/acaf16.

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Abstract In this paper, defect-induced negative thermal quenching (NTQ) of Eu2+-doped phosphors is overviewed. NTQ denotes that the integrated emission intensity of a given phosphor increases continuously with increasing temperature up to a certain elevated temperature. The NTQ phenomenon of Eu2+ luminescence was reportedly observed in a broad variety of lattices. The NTQ of these Eu2+-doped phosphors was generally ascribed to thermally stimulated detrapping of the excitation light stored in defects (traps) and subsequent energy transfer from the defects to the Eu2+ 5d levels. Validity of defect- induced NTQ of Eu2+-doped phosphors is assessed and factors that may contribute to the measured emission intensity of a given phosphor at elevated temperatures are discussed. It is suggested that it is debatable whether NTQ could be an intrinsic property of the blue-emitting phosphor Na3Sc2(PO4)3: Eu2+, and whether the emission intensity enhancement with increasing temperature for Eu2+-doped phosphors could be related to energy transfer from defects. The temperature dependence of the measured emission intensity alone seems not to be a good measure for evaluating TQ property of a phosphor, since it is affected by not only the quantum efficiency of a phosphor but also some extrinsic factors at elevated temperatures.

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Mouloua, D., N. S. Rajput, S. Saitzek, K. Kaja, K. Hoummada, M. El Marssi, M. A. El Khakani et M. Jouiad. « Broadband photodetection using one-step CVD-fabricated MoS2/MoO2 microflower/microfiber heterostructures ». Scientific Reports 12, n^o 1 (21 décembre 2022). http://dx.doi.org/10.1038/s41598-022-26185-z.

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AbstractMolybdenum disulfide (MoS2) has been combined so far with other photodetecting semiconductors as an enhancing agent owing to its optical and electronic properties. Existing approaches demonstrated MoS2-incorporated photodetector devices using complex and costly fabrication processes. Here, we report on simplified one-step on the chemical vapor deposition (CVD) based synthesis of a unique microfiber/microflower MoS2-based heterostructure formed by capturing MoO2 intermediate material during the CVD process. This particular morphology engenders a material chemical and electronic interplay exalting the heterostructure absorption up to ~ 98% over a large spectral range between 200 and 1500 nm. An arsenal of characterization methods were used to elucidate the properties of these novel heterostructures including Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectrometry, high-resolution transmission and scanning electron microscopies, and Kelvin probe force microscopy. Our findings revealed that the MoS2 and the MoO2 crystallize in the hexagonal and monoclinic lattices, respectively. The integration of the MoS2/MoO2 heterostructures into functional photodetectors revealed a strong photoresponse under both standard sun illumination AM1.5G and blue light excitation at 450 nm. Responsivity and detectivity values as high as 0.75 mA W−1 and 1.45 × 107 Jones, respectively, were obtained with the lowest light intensity of 20 mW cm−2 at only 1 V bias. These results demonstrate the high performances achieved by the unique MoS2/MoO2 heterostructure for broadband light harvesting and pave the way for their adoption in photodetection applications.

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