Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA.
Phys Rev Lett. 2013 May 10;110(19):190401. doi: 10.1103/PhysRevLett.110.190401. Epub 2013 May 7.
The understanding of how classical dynamics can emerge in closed quantum systems is a problem of fundamental importance. Remarkably, while classical behavior usually arises from coupling to thermal fluctuations or random spectral noise, it may also be an innate property of certain isolated, periodically driven quantum systems. Here, we experimentally realize the simplest such system, consisting of two coupled, kicked quantum rotors, by subjecting a coherent atomic matter wave to two periodically pulsed, incommensurate optical lattices. Momentum transport in this system is found to be radically different from that in a single kicked rotor, with a breakdown of dynamical localization and the emergence of classical diffusion. Our observation, which confirms a long-standing prediction for many-dimensional quantum-chaotic systems, sheds new light on the quantum-classical correspondence.
理解经典动力学如何在封闭量子系统中出现是一个具有基本重要性的问题。值得注意的是，虽然经典行为通常源于与热涨落或随机频谱噪声的耦合，但它也可能是某些孤立的、周期性驱动的量子系统的固有特性。在这里，我们通过将相干原子物质波暴露于两个周期性脉冲、非调和的光学晶格中来实验实现最简单的此类系统。该系统中的动量输运与单个受迫转子的输运有根本的不同，表现为动力学局域化的破坏和经典扩散的出现。我们的观察结果证实了多维量子混沌系统的一个长期预测，为量子-经典对应关系提供了新的视角。
