论文标题
超时订购的相关器和Loschmidt在量子上踢到顶部的回声：我们能走多低？
Out-of-time-ordered correlators and the Loschmidt echo in the quantum kicked top: How low can we go?
论文作者
论文摘要
超级订购的相关器（OTOC）和Loschmidt Echo是现在广泛探索的两种措施，以表征对复杂量子系统中扰动和信息的敏感性。我们研究了几个量子位系统，共同建模为踢顶，我们可以精确地解决了三量和四量子的情况，从而为OTOC和Loschmidt Echo提供了分析结果。虽然我们可能不会期望如此少的身体系统会显示出半经典的特征，但我们发现即使在适当的制度中，OTOC的指数生长也明确，即使在适当的制度中，铺路方法是可能的实验测量方法。我们在质上解释了诸如固定点和周期轨道之类的经典相空间结构如何影响这些数量，以及我们的结果与大型旋转的顶部模型相比。最后，我们指出了一个特殊的情况，位于量子古典对应关系的边界，可用于任何数量的Qubits，但具有指数灵敏度的签名。
The out-of-time-ordered correlators (OTOC) and the Loschmidt echo are two measures that are now widely being explored to characterize sensitivity to perturbations and information scrambling in complex quantum systems. Studying few qubits systems collectively modelled as a kicked top, we solve exactly the three- and four- qubit cases, giving analytical results for the OTOC and the Loschmidt echo. While we may not expect such few-body systems to display semiclassical features, we find that there are clear signatures of the exponential growth of OTOC even in systems with as low as 4 qubits in appropriate regimes, paving way for possible experimental measurements. We explain qualitatively how classical phase space structures like fixed points and periodic orbits have an influence on these quantities and how our results compare to the large-spin kicked top model. Finally we point to a peculiar case at the border of quantum-classical correspondence which is solvable for any number of qubits and yet has signatures of exponential sensitivity in a rudimentary form.
