调控量子混沌与连续量子测量

Chaos in Continuously Monitored Quantum Systems: An Optimal Path Approach

We predict that continuously monitored quantum dynamics can be chaotic. The optimal paths between past and future boundary conditions can diverge exponentially in time when there is time-dependent evolution and continuous weak monitoring. Optimal paths are defined by extremizing the global probability density to move between two boundary conditions. We investigate the onset of chaos in pure-state qubit systems with optimal paths generated by a periodic Hamiltonian. Specifically, chaotic quantum dynamics are demonstrated in a scheme where two non-commuting observables of a qubit are continuousl…

Efficient Simulation of Quantum Many-body Thermodynamics by Tailoring Zero-temperature Tensor Network

Numerical annealing and renormalization group have conceived various successful approaches to study the thermodynamics of strongly-correlated systems where perturbation or expansion theories fail to work. As the process of lowering the temperatures is usually involved in different manners, these approaches in general become much less efficient or accurate at the low temperatures. In this work, we propose to access the finite-temperature properties from the tensor network (TN) representing the zero-temperature partition function. We propose to "scissor" a finite part from such an infinite-size …

Spectrally-Shaped Continuous-Variable QKD Operating at 500 MHz Over an Optical Pipe Lit by 11 DWDM Channels

We demonstrate high-rate CV-QKD supporting a secure-key rate of 22Mb/s through spectral tailoring and optimal use of quantum receiver bandwidth. Co-existence with 11 adjacent carrier-grade C-band channels spaced by only 20nm is accomplished at >10Mb/s.

诱导并增强由连续监测引起的许多体量子混沌

Inducing, and enhancing, many-body quantum chaos by continuous monitoring

研究通过连续监测Sachdev-Ye-Kitaev模型揭示了监测与热浴共同作用下非热稳态的形成，发现监测可增强热浴抑制的量子混沌动力学。

连续测量下的波包的玻姆力学

Wave Packet under Continuous Measurement via Bohmian Mechanics

利用玻姆力学，给出了连续测量下波包动力学的一种新的量子力学描述。该方程的解是通过波包方法找到的，该方法在经典变量与描述质心动力学的量子变量和波包宽度之间建立了直接相关性。本文所提出的方法给出了一个比较清晰的图片比方法使用限制路径积分和主方程的方法。这项工作显示了如何经典混沌的极不规则特征可以与原子尺度上现象的平滑和波动性质相协调。证明了连续量子测量下的波包同时具有混沌和非混沌的特征。计算了经典粒子和量子波包质心运动轨迹的李雅普诺夫特征指数，证明了它们的混沌性是相同的。尽管如此，波包的宽度表现出非混沌行为，并允许通过瞬态收缩态击败标准量子极限的可能性。

Lyapunov exponents of quantum trajectories beyond continuous measurements

Quantum systems interacting with their environments can exhibit complex non-equilibrium states that are tempting to be interpreted as quantum analogs of chaotic attractors. Yet, despite many attempts, the toolbox for quantifying dissipative quantum chaos remains very limited. In particular, quantum generalizations of Lyapunov exponent, the main quantifier of classical chaos, are established only within the framework of continuous measurements. We propose an alternative generalization which is based on the unraveling of a quantum master equation into an ensemble of so-called 'quantum jump' traj…

基于量子码分多址的连续变量量子密钥分发系统使用混沌相移器

Quantum CDMA-based Continuous Variable Quantum Key Distribution using Chaotic Phase Shifters

本文提出了一种基于量子码分多址的多用户连续变量量子密钥分发系统，利用混沌相移器实现高效信号复用与解复用，通过束 splitter 网络实现不同用户量子态的混沌相位编码与解码，提升密钥分发的安全性与效率。

连续测量下耦合量子系统向经典混沌的转变

The transition to classical chaos in a coupled quantum system through continuous measurement

对量子系统的连续观测产生了一个测量记录，它忠实地再现了经典预测的轨迹，前提是测量足够强以将状态定位在相空间中，但足够弱以使量子反作用噪声可以忽略不计。我们调查的条件下，经典动力学出现，通过连续的位置测量，为一个粒子运动在一个谐波井与其位置耦合到内部自旋。作为这种耦合的结果，我们发现，经典动力学出现时，只有位置和自旋的行动都是大相比，$\hbar$。这些条件被量化的协方差矩阵的大小上放置的界限，它描述了在相空间的扩展区域的离域量子相干性。从这个结果可以得出，对于连续观测到的自旋为1/2的粒子，不存在混合量子-经典区域（其中一个子系统可以被经典地处理，而另一个子系统不能）。当满足经典性的条件时（在大自旋极限下），量子轨道既再现经典的周期轨道，也再现经典的混沌相空间区域。作为这种收敛性的定量测试，我们计算的最大李雅普诺夫指数直接从测量的量子轨迹，并表明它符合经典值。

退相干、混沌、量子-经典对应和时间的算法箭头

Decoherence, chaos, quantum-classical correspondence, and the algorithmic arrow of time

环境--与系统耦合的外部或内部自由度--实际上可以监控它的一些可观测量。结果，这些可观测量的本征态退相干并表现得像经典态：叠加态的连续破坏导致环境诱导的超选择（einselection）。在这里，我在量子混沌的背景下研究它（i。例如，经典混沌系统的量子动力学）。

用于预测实验混沌电子电路的量子极限学习

Quantum extreme learning for forecasting experimental chaotic electronic circuits

本研究针对混沌电子电路的连续时间序列预测问题，采用量子极限学习算法，通过两种离散化方法实现高精度预测，验证了其在近期量子模拟器上处理连续信号的能力及鲁棒性。

非线性拟经典系统的动力学特性

Dynamical peculiarities of the nonlinear quasiclassical systems

分析了非线性经典混沌系统动力学的量子-经典对应。量子混沌问题包括两个部分：混沌系统的准经典量子化和试图用量子力学来理解经典混沌。第一个问题已经部分地用Gutzwiller混沌系统本征值的半经典迹公式解决了，而经典混沌可以由量子方程导出，只需要引入由于与系统环境的相互作用或中频测量引起的退相干过程。我们可以得出结论，连续可观测准经典系统本质上是类经典演化的。

一维的量子混沌？

Quantum chaos in one dimension?

在这项工作中，我们调查的逆著名的Bohigas-Giannoni-Schmit猜想。利用两种反演方法计算了一个最低N个特征值服从随机矩阵统计的一维势。我们的数值结果表明，在渐近极限，N->无穷大，解决方案是无处可微，最有可能无处连续。这样的反例是不存在的。