Quantum resources of the steady-state of three coupled qubits: Microscopic versus Phenomenological model

Quantum versus classical approach of dechanneling and incoherent electromagnetic processes in aligned crystals

Particles traveling in aligned crystals at small angles w.r.t. crystallographic axes or planes are principally steered by the continuous Lindhard potential. This interaction conserves the energy E, the longitudinal momentum p_parallel, the transverse energy of the particle E_perp and is elastic concerning the crystal quantum state. At high enough energy the particle motion is quasi-classical. The time-dependent fluctuations of the positions of the atoms or of the electrons of the crystal create a residual potential, on which the particle can scatter. This interaction does not conserve the prev…

双光子驱动下耗散克尔腔的零差与光子计数量子轨道

Homodyne versus photon-counting quantum trajectories for dissipative Kerr resonators with two-photon driving

我们研究了两种不同的量子轨道的非线性光子谐振腔受双光子泵浦，最近研究的配置为光子薛定谔猫态的产生。在没有反馈控制和强驱动极限下，稳态密度矩阵是两个具有相等权重的状态的统计混合。虽然沿着一个单一的光子计数轨迹的系统间歇性切换之间的奇数和偶数猫状态，我们表明，零差检测的情况是不同的。实际上，零拍量子轨迹揭示了相反相位的相干态之间的转换。

Nonequilibrium system-bath entanglement theorem versus heat transport

In this work, we extend the recently established system-bath entanglement theorem (SBET) [J. Chem. Phys. 152, 034102 (2020)] to the nonequilibrium scenario, in which an arbitrary system couples to multiple Gaussian baths environments at different temperatures. While the existing SBET connects the entangled system-bath response functions to those of local systems, the extended theory is concerned with the nonequilibrium steady-state quantum transport current through molecular junctions. The new theory is established on the basis of the generalized Langevin equation, with a close relation to non…

非马尔可夫量子动力学的时间非局域与时间局域长时间外推

Time-nonlocal versus time-local long-time extrapolation of non-Markovian quantum dynamics

本文提出一种基于时间局域动力学映射平稳性的简单外推方法，用于预测非马尔可夫量子系统长时间行为，并在自旋-玻色子模型上证明其收敛速度不慢于转移张量方法，表明时间非局域性并非高效外推的必要条件。

Quantum versus classical switching dynamics of driven-dissipative Kerr resonators

We report a first-principles study of the driven dissipative dynamics for Kerr oscillators in the mesoscopic regime. This regime is characterized by large Kerr nonlinearity, realized here using the nonlinear kinetic inductance of a large array of Josephson junctions. The experimentally measured nonlinear resonance lineshapes of the junction array modes show significant deviations from steady-state numerical predictions, and necessitate time-dependent numerical simulations indicative of strong measurement-induced dephasing in the system arising from the large cross-Kerr effect between array mod…

Explaining versus Describing Human Decisions. Hilbert Space Structures in Decision Theory

Despite the impressive success of quantum structures to model long-standing human judgement and decision puzzles, the {\it quantum cognition research programme} still faces challenges about its explanatory power. Indeed, quantum models introduce new parameters, which may fit empirical data without necessarily explaining them. Also, one wonders whether more general non-classical structures are better equipped to model cognitive phenomena. In this paper, we provide a {\it realistic-operational foundation of decision processes} using a known decision-making puzzle, the {\it Ellsberg paradox}, as …

XXZ交错模型与SYK模型在幺正及受监测量子动力学中的非稳定子性

Nonstabilizerness in the unitary and monitored quantum dynamics of XXZ-staggered and SYK models

本文用量子轨迹与稳定子Rényi熵研究XXZ交错链和SYK模型的幺正及受监测动力学，发现仅SYK呈现混沌随机态标度，而测量下稳态SRE随系统尺寸线性增长且无相变。

Non-equilibrium stationary states of quantum non-Hermitian lattice models

We show how generic non-Hermitian tight-binding lattice models can be realized in an unconditional, quantum-mechanically consistent manner by constructing an appropriate open quantum system. We focus on the quantum steady states of such models for both fermionic and bosonic systems. Surprisingly, key features and spatial structures in the steady state cannot be simply understood from the non-Hermitian Hamiltonian alone. Using the 1D Hatano-Nelson model as a paradigmatic example, we show that the steady state has a marked sensitivity to boundary conditions. This dependence however is qualitativ…

Dephasing versus collapse: Lessons from the tight-binding model with noise

Condensed matter physics at room temperature usually assumes that electrons in conductors can be described as spatially narrow wave packets - in contrast to what the Schrödinger equation would predict. How a finite-temperature environment can localize wave functions is still being debated. Here, we represent the environment by a fluctuating potential and investigate different unravellings of the Lindblad equation that describes the one-dimensional tight-binding model in the presence of such a potential. While all unravellings show a fast loss of phase coherence, only part of them lead to narro…

高阶空间光子干涉与偶极子阻塞效应

Higher-order spatial photon interference versus dipole blockade effect

研究通过分析三个偶极子耦合发射体与热浴的相互作用，揭示了高阶空间光子干涉与偶极子阻塞效应的量子特性及起源。

非马尔可夫量子多体系统中的耗散与混沌诱导松弛

Dissipation- versus Chaos-Induced Relaxation in Non-Markovian Quantum Many-Body Systems

研究揭示了非马尔可夫环境在量子多体系统中通过耗散与混沌竞争诱导不同弛豫机制的动态相图。

Coherent Scattering of Near-Resonant Light by a Dense, Microscopic Cloud of Cold Two-Level Atoms: Experiment versus Theory

We measure the coherent scattering of low-intensity, near-resonant light by a cloud of laser-cooled two-level rubidium atoms with a size comparable to the wavelength of light. We isolate a two-level atomic structure by applying a 300G magnetic field. We measure both the temporal and the steady-state coherent optical response of the cloud for various detunings of the laser and for atom numbers ranging from 5 to 100. We compare our results to a microscopic coupled-dipole model and to a multi-mode, paraxial Maxwell-Bloch model. In the low-intensity regime, both models are in excellent agreement, …