We show a procedure for engineering effective interactions between two modes in a bimodal cavity. Our system consists of one or more two-level atoms, excited by a classical field, interacting with both modes. The two effective Hamiltonians have a similar form of a beam-splitter and quadratic beam-splitter interactions, respectively. We also demonstrate that the nonlinear Hamiltonian can be used to prepare an entangled coherent state, also known as multidimensional entangled coherent state, which has been pointed out as an important entanglement resource. We show that the nonlinear interaction parameter can be enhanced considering N independent atoms trapped inside a high-finesse optical cavity.
We investigate the generation of single photons and photon pairs in a cavity quantum electrodynamics system of a four-level quantum dot coupled to bimodal cavity. By tuning frequencies and intensity ratio of the driving lasers, sub-Poissonian and super-Poissonian photon statistics are obtained in each nondegenerate cavity mode respectively. Single photon emission is characterized as zero-delay second-order correlation function g^2(0)~0.15. Photon pair emission under the two-photon resonance excitation is quantified by Mandel parameter as Q~0.04. The mean cavity photon number in both scenarios …
We describe a scheme of deterministic single-photon subtraction in a solid-state system consisting of a charged quantum dot coupled to a bimodal photonic-crystal cavity with a moderate magnetic field applied in a Voigt configuration. We numerically simulate injection of optical pulses into one of the modes of the bimodal cavity and show that the system deterministically transfers one photon into the second cavity mode for input pulses in the form of both Fock states and coherent states.
We report dissipative dynamics of two valley excitons residing in the $K$ and $K^\prime$-valleys of bare WSe$_2$ monolayer and the one being integrated into a bimodal optical cavity. In the former, only when the exciton-field detunings in the $K$ and $K^\prime$-valleys are rigorously equal (resonant detuning), partially entangled stationary states can be created. Otherwise the concurrence of exciton qubits turns to zero. Remarkably, in the latter (the WSe$_2$ monolayer in a bimodal optical cavity), the transfers of entanglement from one subsystem (exciton/light) to the other (light/exciton) ta…
Single photons and single-photon pairs, inherently nonclassical in their nature, are fundamental elements of quantum sciences and technologies. Here, we propose to realize the nonclassical correlated deterministic photon pairs at the single-photon level for a single atom trapped in bimodal cavities. It is shown that the photon emissions for bimodal cavities exhibit a high single photon purity and relatively large intracavity photon numbers, which are ascribed to the combination of optical Stark shift enhanced energy-spectrum anharmonicity and quantum interference suppressed two-photon excitati…
Coherence has been remaining a key resource for numerous applications of quantum physics ranging from quantum metrology to quantum information. Here, we report a theoretical work on how maximally created coherence results in the squeezing of cavity field coupled to a coherently driven single quantum dot. We employ a recently developed polaron master equation theory for accurately incorporating the impact of exciton-phonon coupling on squeezing.
Exchange-controlled quantum beats and entanglement in an exciton--bimodal-cavity system
Federal University of Santa Maria（圣玛丽亚联邦大学）；Universidad Privada del Norte（北方私立大学）；Institute for Basic Science (IBS)（基础科学研究院）；Ewha Womans University（梨花女子大学）
A cavity-mediated reconfigurable coupling scheme for superconducting qubits
Pritzker School of Molecular Engineering, University of Chicago（芝加哥大学普里茨克分子工程学院）；Institute of Applied Physics, Seoul National University（首尔国立大学应用物理研究所）；NextQuantum Innovation Research Center, Seoul National University（首尔国立大学NextQuantum创新中心）；Department of Physics and Astronomy, Seoul National University（首尔国立大学物理与天文学系）
Loophole-free Bell-inequality violation between atomic states in cavity-QED systems mediated by hybrid atom-light entanglement
Okinawa Institute of Science and Technology Graduate University（冲绳科学技术大学院大学）；NextQuantum Innovation Research Center, Department of Physics & Astronomy, Seoul National University（首尔大学物理与天文学系 NextQuantum 创新中心）；Department of Physics, SRM University, Amaravati, Andhra Pradesh - 522540, India（印度安得拉邦阿马拉瓦蒂 SRM 大学物理系）；National Institute of Informatics（国立情报学研究所）
We present a quantum-state-diffusion equation to characterize the dynamics of a generic atomic system coupled to a leaky cavity mode. As quantum resources, the population, the coherence and even the entanglement of the system would gradually leak out of the cavity. The effect from the leakage of the cavity-mode to the uncontrollable degree of freedom, e.g., environment, is however not always negative to particular targets. A well-established scenario is that a photon counter attached to the cavity would absorb and then record the leaking photon. As a medium between the system and the photon co…
Quantum logic gates are fundamental building blocks of quantum computers. Their integration into quantum networks requires strong qubit coupling to network channels, as can be realized with neutral atoms and optical photons in cavity quantum electrodynamics. Here we demonstrate that the long-range interaction mediated by a flying photon performs a gate between two stationary atoms inside an optical cavity from which the photon is reflected. This single step executes the gate in $2\,\mathrm{μs}$. We show an entangling operation between the two atoms by generating a Bell state with 76(2)% fideli…
We propose an approach to simultaneously excite two atoms by using cavity-assisted Raman process in combination with cavity photon-mediated interaction. The system consists of a two-level atom and a $Λ$-type or V-type three-level atom, which are coupled together with a cavity mode. Having derived the effective Hamiltonian, we find that under certain circumstances a single photon can simultaneously excite two atoms. In addition, multiple photons and even a classical field can also simultaneously excite two atoms. As an example, we show a scheme to realize our proposal in a circuit QED setup, wh…
We characterize some of the distinctive hallmarks of magnon-magnon interaction mediated by the intracavity field of a microwave cavity, along with their testable ramifications. In general, we foreground two widely dissimilar parameter domains that bring forth the contrasting possibilities of level splitting and level crossing. The former is observed in the regime of strong magnon-photon couplings, particularly when the three modes bear comparable relaxation rates. This character is marked by the appearance of three distinguishable and non-converging polariton branches in the spectral response …
We analyze the requirements for fault-tolerant quantum computation with atom-atom gates based on cavity quantum electrodynamics (cQED) mediated by a photon with a finite pulse length. For short photon pulses, the distorted shape of the reflected pulses from the cQED system is a serious error source. We optimize the cQED system parameters to minimize the infidelity due to the shape distortion and the photon losses in a well-balanced manner for the fault-tolerant scheme using probabilistic gates [H. Goto and K. Ichimura, Phys. Rev. A 80, 040303(R) (2009)]. Our optimization greatly relaxes the re…
In this paper, we identify a many-particle phonon expectation value $ζ$ with the ability to induce collective dynamics in a non-interacting atomic gas inside an optical cavity. We then propose to utilise this expectation value to enhance the laser cooling of many atoms through a cyclic two-stage process which consists of cooling and displacement stages. During cooling stages, short laser pulses are applied. These use $ζ$ as a resource and decrease the vibrational energy of the atomic gas by a fixed amount. Subsequent displacement stages use the asymmetry of the trapping potential to replenish …
The recent realization of a coherent interface between a single electron in a silicon quantum dot and a single photon trapped in a superconducting cavity opens the way for implementing photon-mediated two-qubit entangling gates. In order to couple a spin to the cavity electric field some type of spin-charge hybridization is needed, which impacts spin control and coherence. In this work we propose a cavity-mediated two-qubit gate and calculate cavity-mediated entangling gate fidelities in the dispersive regime, accounting for errors due to the spin-charge hybridization, as well as photon- and p…
We propose a theoretical scheme to achieve strong photon blockade via a single atom in cavity. By utilizing optical Stark shift, the dressed-state splitting between higher and lower branches is enhanced, which results in significant increasing for lower (higher) branch and decreasing for higher (lower) branch at the negative (positive) Stark shift, and dominates the time-evolution of photon number oscillations as well. Furthermore, the two-photon excitation is suppressed via quantum interference under optimal phase and Rabi frequency of an external microwave field. It is shown that the interpl…
We show that an atom can be coupled to a mechanical oscillator via quantum vacuum fluctuations of a cavity field enabling energy transfer processes between them. In a hybrid quantum system consisting of a cavity resonator with a movable mirror and an atom, these processes are dominated by two pair-creation mechanisms: the counterrotating (atom-cavity system) and dynamical Casimir interaction terms (optomechanical system). Because of these two pair-creation mechanisms, the resonant atom-mirror coupling is the result of high-order virtual processes with different transition paths well described …
AWS Center for Quantum Computing（亚马逊量子计算中心）；Kavli Nanoscience Institute and Thomas J. Watson, Sr., Laboratory of Applied Physics, California Institute of Technology（加州理工学院卡弗里纳米科学研究所和托马斯·J·沃森 Sr. 应用物理实验室）；Institute for Quantum Information and Matter, California Institute of Technology（加州理工学院量子信息与物质研究所）；Racah Institute of Physics（拉卡赫物理研究所）
Cavity-mediated two-qubit gates, for example between solid-state spins, are attractive for quantum network applications. We propose three schemes to implement a controlled phase-flip gate mediated by a cavity. The main advantage of all these schemes is the possibility to perform them using a cavity with high cooperativity, but not in the strong coupling regime. We calculate the fidelity of each scheme in detail, taking into account the most important realistic imperfections, and compare them to highlight the optimal conditions for each scheme. Using these results, we discuss which quantum syst…
Cavity-mediated coherence protection and one-axis twisting for spins in solids
California Institute of Technology（加州理工学院）；Chimie ParisTech, PSL University, CNRS, Institut de Recherche de Chimie Paris（巴黎化学学院，巴黎文理研究大学，法国国家科学研究中心，巴黎化学研究院）
