Chaos, entanglement, and decoherence in the quantum kicked top

We analyze the interplay of chaos, entanglement, and decoherence in a system of qubits whose collective behavior is that of a quantum kicked top. The dynamical entanglement between a single qubit and the rest can be calculated from the mean of the collective spin operators. This allows the possibility of efficiently measuring entanglement dynamics in an experimental setting. We consider a deeply quantum regime and show that signatures of chaos are present in the dynamical entanglement for parameters accessible in an experiment that we propose using cold atoms. The evolution of the entanglement depends on the support of the initial state on regular versus chaotic Floquet eigenstates, whose phase-space distributions are concentrated on the corresponding regular or chaotic eigenstructures. We include the effect of decoherence via a realistic model and show that the signatures of chaos in the entanglement dynamics persist in the presence of decoherence. In addition, the classical chaos affects the decoherence rate itself.

我们分析了量子比特系统中混沌、纠缠和退相干之间的相互作用，该系统的集体行为类似于量子受激陀螺。单个量子比特与其他量子比特之间的动态纠缠可以通过集体自旋算符的平均值来计算。这使得在实验环境中高效测量纠缠动力学成为可能。我们考虑了一种深度量子态，并表明在我们提出的使用冷原子的实验中可达到的参数下，动态纠缠中存在混沌的特征。纠缠的演化取决于初始态在规则与混沌的弗洛凯本征态上的支撑，其相空间分布集中在相应的规则或混沌本征结构上。我们通过一个实际的模型考虑了退相干的影响，并表明在存在退相干的情况下，纠缠动力学中的混沌特征依然存在。此外，经典混沌本身会影响退相干速率。