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Yifu Zhu - One of the best experts on this subject based on the ideXlab platform.

  • coherent perfect absorption in a Quantum nonlinear regime of Cavity Quantum Electrodynamics
    Physical Review A, 2018
    Co-Authors: Yanghua Wei, Guoqing Yang, Yifu Zhu
    Abstract:

    Coherent perfect absorption (CPA) is investigated in the Quantum nonlinear regime of Cavity Quantum Electrodynamics (CQED), in which a single two-level atom couples to a single-mode Cavity weakly driven by two identical laser fields. In the strong-coupling regime and due to the photon blockade effect, the weakly driven CQED system can be described as a Quantum system with three polariton states. CPA is achieved at a critical input field strength when the frequency of the input fields matches the polariton transition frequency. In the Quantum nonlinear regime, the incoherent dissipation processes such as atomic and photon decays place a lower bound for the purity of the intraCavity Quantum field. Our results show that under the CPA condition, the intraCavity field always exhibits the quadrature squeezing property manifested by the Quantum nonlinearity, and the outgoing photon flux displays the super-Poissonian distribution.

  • control of optical bistability in the nonlinear regime of two sided Cavity Quantum Electrodynamics
    Journal of The Optical Society of America B-optical Physics, 2017
    Co-Authors: Liyong Wang, Yifu Zhu, Zheng Tan, Mingsheng Zhan
    Abstract:

    We investigate the optical bistability behavior of a two-sided Cavity Quantum Electrodynamics system. The non-linear input - output relation of the atom - Cavity system coupled by two input light fields from two ends of the Cavity can be controlled by a control light from the free space. Different from the common optical bistability phenomenon in the atom - Cavity system, two separate bistability regions are observed. The bistability threshold and hysteresis loop can be well controlled by the control light. Because of field interference, the output light intensity becomes different with varying the relative phase of two incident fields. The output field intensity at the threshold of the first bistability region approaches zero with either increasing the detuning or lowering the intensity of the control light; thus, the perfect photon absorption condition is extended and a broadband near-perfect photon absorber is realized. Furthermore, we show an asymmetrical transmission feature due to field interference. (C) 2017 Optical Society of America

  • Perfect photon absorption in the nonlinear regime of Cavity Quantum Electrodynamics
    Physical Review A, 2016
    Co-Authors: Girish S. Agarwal, Liyong Wang, Yifu Zhu
    Abstract:

    It has been shown that perfect photon absorption can occur in the linear excitation regime of Cavity Quantum Electrodynamics (CQED), in which photons from two identical light fields coupled into two ends of the Cavity are completely absorbed and result in excitation of the polariton state of the CQED system. The output light from the Cavity is totally suppressed by destructive interference and the polariton state can only decay incoherently back to the ground state. Here we analyze perfect photon absorption and the onset of optical bistability in the nonlinear regime of the CQED and show that perfect photon absorption persists in the nonlinear regime of the CQED below the threshold of optical bistability. Therefore perfect photon absorption is a phenomenon that can be observed in both linear and nonlinear regimes of CQED. Furthermore, our study reveals that optical bistability is influenced by input-light interference and can be manipulated by varying the relative phase of the two input fields.

Jelena Vuckovic - One of the best experts on this subject based on the ideXlab platform.

  • photon blockade in weakly driven Cavity Quantum Electrodynamics systems with many emitters
    Physical Review Letters, 2019
    Co-Authors: Rahul Trivedi, Marina Radulaski, Kevin A Fischer, Shanhui Fan, Jelena Vuckovic
    Abstract:

    We use the scattering matrix formalism to analyze photon blockade in coherently driven Cavity Quantum Electrodynamics systems with a weak drive. By approximating the weak coherent drive by an input single- and two-photon Fock state, we reduce the computational complexity of the transmission and the two-photon correlation function from exponential to polynomial in the number of emitters. This enables us to easily analyze Cavity-based systems containing ∼50 Quantum emitters with modest computational resources. Using this approach we study the coherence statistics of photon blockade while increasing the number of emitters for resonant and detuned multiemitter Cavity Quantum Electrodynamics systems-we find that increasing the number of emitters worsens photon blockade in resonant systems, and improves it in detuned systems. We also analyze the impact of inhomogeneous broadening in the emitter frequencies on the photon blockade through this system.

  • Cavity Quantum Electrodynamics with a single Quantum dot coupled to a photonic molecule
    Physical Review B, 2012
    Co-Authors: Arka Majumdar, Armand Rundquist, Michal Bajcsy, Jelena Vuckovic
    Abstract:

    We demonstrate the effects of Cavity Quantum Electrodynamics for a Quantum dot coupled to a photonic molecule, consisting of a pair of coupled photonic crystal cavities. We show anti-crossing between the Quantum dot and the two super-modes of the photonic molecule, signifying achievement of the strong coupling regime. From the anti-crossing data, we estimate the contributions of both mode-coupling and intrinsic detuning to the total detuning between the super-modes. Finally, we also show signatures of off-resonant Cavity-Cavity interaction in the photonic molecule.

  • photonic crystal microcavities for Cavity Quantum Electrodynamics with a single Quantum dot
    Applied Physics Letters, 2003
    Co-Authors: Jelena Vuckovic, Yoshihisa Yamamoto
    Abstract:

    We propose a planar photonic crystal microCavity design specially tailored for Cavity Quantum Electrodynamics with a single Quantum dot emitter embedded in semiconductor. With quality factor up to 45 000, mode volume smaller than a cubic optical wavelength in material, and electric field maximum located in the high-refractive index region at the Cavity center, this design can enable both strong coupling and lasing with a single Quantum dot exciton. The achievable range of the quality factor to mode volume ratios and the feasible fabrication of the proposed structure make it favorable to other semiconductor microcavities.

  • optimization of three dimensional micropost microcavities for Cavity Quantum Electrodynamics
    Physical Review A, 2002
    Co-Authors: Jelena Vuckovic, Matthew Pelton, Axel Scherer, Yoshihisa Yamamoto
    Abstract:

    This paper presents a detailed analysis, based on the first-principles finite-difference time-domain method, of the resonant frequency, quality factor (Q), mode volume (V), and radiation pattern of the fundamental (HE11) mode in a three-dimensional distributed-Bragg-reflector (DBR) micropost microCavity. By treating this structure as a one-dimensional cylindrical photonic crystal containing a single defect, we are able to push the limits of Q/V beyond those achievable by standard micropost designs, based on the simple rules established for planar DBR microcavities. We show that some of the rules that work well for designing large-diameter microposts (e.g., high-refractive-index contrast) fail to provide high-quality cavities with small diameters. By tuning the thicknesses of mirror layers and the spacer, the number of mirror pairs, the refractive indices of high- and low-refractive index regions, and the Cavity diameter, we are able to achieve Q as high as 10(4), together with a mode volume of 1.6 cubic wavelengths of light in the high-refractive-index material. The combination of high Q and small V makes these structures promising candidates for the observation of such Cavity-Quantum-Electrodynamics phenomena as strong coupling between a Quantum dot and the Cavity field, and single-Quantum-dot lasing.

Arno Rauschenbeutel - One of the best experts on this subject based on the ideXlab platform.

  • nanofiber fabry perot microresonator for nonlinear optics and Cavity Quantum Electrodynamics
    Optics Letters, 2012
    Co-Authors: C Wuttke, Sven Brückner, Martin Becker, Manfred Rothhardt, Arno Rauschenbeutel
    Abstract:

    We experimentally realize a Fabry–Perot-type optical microresonator near the cesium D2 line wavelength based on a tapered optical fiber, equipped with two fiber Bragg gratings that enclose a subwavelength diameter waist. Owing to the very low taper losses, the finesse of the resonator reaches F=86 while the on-resonance transmission is T=11%. The characteristics of our resonator fulfill the requirements of nonlinear optics and Cavity Quantum Electrodynamics in the strong coupling regime. These characteristics, combined with the demonstrated ease of use and advantageous mode geometry, open a realm of applications.

  • tunable whispering gallery mode resonators for Cavity Quantum Electrodynamics
    Physical Review A, 2005
    Co-Authors: Y Louyer, Dieter Meschede, Arno Rauschenbeutel
    Abstract:

    We theoretically study the properties of highly prolate-shaped dielectric microresonators. Such resonators sustain whispering-gallery modes that exhibit two spatially well-separated regions with enhanced field strength. The field per photon on the resonator surface is significantly higher than, e.g., for equatorial whispering-gallery modes in microsphere resonators with a comparable mode volume. At the same time, the frequency spacing of these modes is much more favorable, so that a tuning range of several free spectral ranges should be attainable. We discuss the possible application of such resonators for Cavity Quantum Electrodynamics experiments with neutral atoms and reveal distinct advantages with respect to existing concepts.

Franco Nori - One of the best experts on this subject based on the ideXlab platform.

  • resolution of gauge ambiguities in ultrastrong coupling Cavity Quantum Electrodynamics
    Nature Physics, 2019
    Co-Authors: Omar Di Stefano, Alessio Settineri, Vincenzo Macri, Luigi Garziano, Roberto Stassi, Salvatore Savasta, Franco Nori
    Abstract:

    In Quantum Electrodynamics, the choice of gauge influences the form of light–matter interactions. However, gauge invariance implies that all physical results should be independent of this formal choice. The Rabi model, a widespread description for the dipolar coupling between a two-level atom and a quantized electromagnetic field, seemingly violates this principle in the presence of ultrastrong light–matter coupling, a regime that is now experimentally accessible in many physical systems. This failure is attributed to the finite-level truncation of the matter system, an approximation that enters the derivation of the Rabi model. Here, we identify the source of gauge violation and provide a general method for the derivation of light–matter Hamiltonians in truncated Hilbert spaces that produces gauge-invariant physical results, even for extreme light–matter interaction regimes. This is achieved by compensating the non-localities introduced in the construction of the effective Hamiltonians. The resulting Quantum Rabi Hamiltonian in the Coulomb gauge differs significantly in form from the standard one, but provides the same physical results obtained by using the dipole gauge. These results shed light on gauge invariance in the non-perturbative and extreme-interaction regimes, and solve long-lasting controversies arising from gauge ambiguities in the Quantum Rabi and Dicke models. The principle of gauge invariance in Quantum Electrodynamics may be violated by approximate models in the presence of strong light–matter interactions. A general approach solves gauge ambiguities and offers a way to construct gauge-invariant Hamiltonians.

  • resolution of superluminal signalling in non perturbative Cavity Quantum Electrodynamics
    arXiv: Quantum Physics, 2017
    Co-Authors: Carlos Sanchez Munoz, Franco Nori, Simone De Liberato
    Abstract:

    Recent technological developments have made it increasingly easy to access the non-perturbative regimes of Cavity Quantum Electrodynamics known as ultra or deep strong coupling, where the light-matter coupling becomes comparable to the bare modal frequencies. In this work, we address the adequacy of the broadly used single-mode Cavity approximation to describe such regimes. We demonstrate that, in the non-perturbative light-matter coupling regimes, the single-mode models become unphysical, allowing for superluminal signalling. Moreover, considering the specific example of the Quantum Rabi model, we show that the multi-mode description of the electromagnetic field, necessary to account for light propagation at finite speed, yields physical observables that differ radically from their single-mode counterparts already for moderate values of the coupling. Our multi-mode analysis also reveals phenomena of fundamental interest on the dynamics of the intraCavity electric field, where a free photonic wavefront and a bound state of virtual photons are shown to coexist.

  • Cavity Quantum Electrodynamics with ferromagnetic magnons in a small yttrium iron garnet sphere
    arXiv: Quantum Physics, 2015
    Co-Authors: Dengke Zhang, Franco Nori, Xinming Wang, Xiaoqing Luo, J Q You
    Abstract:

    Hybridizing collective spin excitations and a Cavity with high cooperativity provides a new research subject in the field of Cavity Quantum Electrodynamics and can also have potential applications to Quantum information. Here we report an experimental study of Cavity Quantum Electrodynamics with ferromagnetic magnons in a small yttrium-iron-garnet (YIG) sphere at both cryogenic and room temperatures. We observe for the first time a strong coupling of the same Cavity mode to both a ferromagnetic-resonance (FMR) mode and a magnetostatic (MS) mode near FMR in the Quantum limit. This is achieved at a temperature ~ 22 mK, where the average microwave photon number in the Cavity is less than one. At room temperature, we also observe strong coupling of the Cavity mode to the FMR mode in the same YIG sphere and find a slight increase of the damping rate of the FMR mode. These observations reveal the extraordinary robustness of the FMR mode against temperature. However, the MS mode becomes unobservable at room temperature in the measured transmission spectrum of the microwave Cavity containing the YIG sphere. Our numerical simulations show that this is due to a drastic increase of the damping rate of the MS mode.

  • Cavity Quantum Electrodynamics with ferromagnetic magnons in a small yttrium iron garnet sphere
    npj Quantum Information, 2015
    Co-Authors: Dengke Zhang, Franco Nori, Xinming Wang, Xiaoqing Luo, J Q You
    Abstract:

    Hybridizing collective spin excitations and a Cavity with high cooperativity provides a new research subject in the field of Cavity Quantum Electrodynamics and can also have potential applications to Quantum information. Here we report an experimental study of Cavity Quantum Electrodynamics with ferromagnetic magnons in a small yttrium-iron-garnet (YIG) sphere at both cryogenic and room temperatures. We observe for the first time a strong coupling of the same Cavity mode to both a ferromagnetic-resonance (FMR) mode and a magnetostatic (MS) mode near FMR in the Quantum limit. This is achieved at a temperature ~22 mK, where the average microwave photon number in the Cavity is less than one. At room temperature, we also observe strong coupling of the Cavity mode to the FMR mode in the same YIG sphere and find a slight increase of the damping rate of the FMR mode. These observations reveal the extraordinary robustness of the FMR mode against temperature. However, the MS mode becomes unobservable at room temperature in the measured transmission spectrum of the microwave Cavity containing the YIG sphere. Our numerical simulations show that this is due to a drastic increase of the damping rate of the MS mode. New research unveils Quantum-coherence properties of ferromagnetic magnons in a magnetic sphere at both cryogenic and room temperatures. Tie-Fu Li and J. Q. You from the Beijing Computational Science Research Center, along with collaborators in China, Japan and the USA, placed a submillimeter yttrium-iron-garnet (YIG) sphere within a three-dimensional microwave Cavity. They observed a strong interaction between the ferromagnetic resonances of the small magnetic sphere and photons in the surrounding Cavity, and confirmed that single photons in the Cavity showed strong and robust coupling with the collective spin excitations of magnetic YIG. The coupling extended from cryogenic temperatures up to room temperature, emphasizing the considerable practical potential of this system. These findings remind us that the interaction of different Quantum systems can lead to properties unknown to classical systems, revealing potential practical applications.

Cristiano Ciuti - One of the best experts on this subject based on the ideXlab platform.