Multimode-polariton superradiance via Floquet engineering

Multimode N00N states in driven atomtronic circuits

We propose a method to generate multi-mode N00N states with arrays of ultracold atoms. Our protocol requires a strong relative offset among the wells and a drive of the interparticle interaction at a frequency resonant with the offsets. The proposal is demonstrated by a numerical and a Floquet analysis of the quantum dynamics of a ring-shaped atomtronics circuit made of M weakly coupled optical traps. We generate a hierarchy of energy scales down to very few low-energy states where N00N dynamics takes place, making multi-mode N00N states appear at nearly regular time intervals. The production …

Super- and subradiance of clock atoms in multimode optical waveguides

The transversely confined propagating modes of an optical fiber mediate virtually infinite range energy exchanges among atoms placed within their field, which adds to the inherent free space dipole-dipole coupling. Typically, the single atom free space decay rate largely surpasses the emission rate into the guided fiber modes. However, scaling up the atom number as well as the system size amounts to entering a collective emission regime, where fiber-induced superradiant spontaneous emission dominates over free space decay. We numerically study this super- and subradiant decay of highly excited…

Dynamical Casimir effect in dissipative optomechanical cavity interacting with photonic crystal

We theoretically study the dynamical Casimir effect (DCE), i.e., parametric amplification of a quantum vacuum, in an optomechanical cavity interacting with a photonic crystal, which is considered to be an ideal system to study the microscopic dissipation effect on the DCE. Starting from a total Hamiltonian including the photonic band system as well as the optomechanical cavity, we have derived an effective Floquet-Liouvillian by applying the Floquet method and Brillouin-Wigner-Feshbach projection method. The microscopic dissipation effect is rigorously taken into account in terms of the energy…

统一的光-物质Floquet理论及其在量子通信中的应用

Unified Light-Matter Floquet Theory and its Application to Quantum Communication

本文提出光子分辨Floquet理论（PRFT），将Floquet理论与量子光学统一，揭示多模光场导致原子退相干，并据此设计出性能超越现有少光子协议两个数量级的量子通信方案。

基于多泵四波混频的微观多模生成模型

Microscopic model for a spatial multimode generation based on Multi-pump Four Wave Mixing in hot vapours

本文提出基于双泵四波混频的多模生成模型，通过扩展双Λ模型并引入傅里叶展开方法，描述多模生成的角度依赖性和量子关联，并用于预测增益分布和量子关联。

Driven-Dissipative Dynamics of Atomic Ensembles in a Resonant Cavity I: Nonequilibrium Phase Diagram and Periodically Modulated Superradiance

We study the dynamics of two ensembles of atoms (or equivalently, atomic clocks) coupled to a bad cavity and pumped incoherently by a Raman laser. Our main result is the nonequilibrium phase diagram for this experimental setup in terms of two parameters - detuning between the clocks and the repump rate. There are three main phases - trivial steady state (Phase I), where all atoms are maximally pumped, nontrivial steady state corresponding to monochromatic superradiance (Phase II), and amplitude-modulated superradiance (Phase III). Phases I and II are fixed points of the mean-field dynamics, wh…

Dissipative dynamical Casimir effect in terms of the complex spectral analysis in the symplectic-Floquet space

Dynamical Casimir effect of the optomechanical cavity interacting with one-dimensional photonic crystal is theoretically investigated in terms of the complex spectral analysis of Floquet-Liouvillian in the symplectic-Floquet space. The quantum vacuum fluctuation of the intra-cavity mode is parametrically amplified by a periodic motion of the mirror boundary, and the amplified photons are spontaneously emitted to the photonic band. We have derived the non-Hermitian effective Floquet-Liouvillian from the total system Liouvillian with the use of the Brillouin-Wigner-Feshbach projection method in …

Nonreciprocal transport based on cavity Floquet modes in optomechanics

Directional transport is obtained in various multimode systems by driving multiple, nonreciprocally-interfering interactions between individual bosonic modes. However, systems sustaining the required number of modes become physically complex. In our microwave-optomechanical experiment, we show how to configure nonreciprocal transport between frequency components of a single superconducting cavity coupled to two drumhead oscillators. The frequency components are promoted to Floquet modes and generate the missing dimension to realize an isolator and a directional amplifier. A second cavity left …

Intertwined and vestigial order with ultracold atoms in multiple cavity modes

Atoms in transversely pumped optical cavities "self-organize" by forming a density wave and emitting superradiantly into the cavity mode(s). For a single-mode cavity, the properties of this self-organization transition are well characterized both theoretically and experimentally. Here, we explore the self-organization of a Bose-Einstein condensate in the presence of two cavity modes---a system that was recently experimentally realized [Leonard \emph{et al.}, \emph{Nature} {\bf 543}, 87 (2017)]. We argue that this system can exhibit a "vestigially ordered" phase in which neither cavity mode exh…

高协同性共焦腔QED显微镜

A high-cooperativity confocal cavity QED microscope

本研究展示共焦腔QED显微镜可实现超过110的协同性，与最佳单模腔相当，并提供1.7微米成像分辨率，通过超辐射阈值测量验证，理论揭示近简并模式色散耦合增强协同性。