Atom-optics kicked rotor represents an experimentally reliable version of the paradigmatic quantum kicked rotor system. In this system, a periodic sequence of kicks are imparted to the cold atomic cloud. After a short initial diffusive phase the cloud settles down to a stationary state due to the onset of dynamical localization. In this paper, to explore the interplay between localized and diffusive phases, we experimentally implement a modification to this system in which the sign of the kick sequence is flipped after every $M$ kicks. This is achieved in our experiment by allowing free evolution for half the Talbot time after every $M$ kicks. Depending on the value of $M$, this modified system displays a combination of enhanced diffusion followed by asymptotic localization. This is explained as resulting from two competing processes—localization induced by standard kicked rotor type kicks, and diffusion induced by the half Talbot time evolution. The experimental and numerical simulations agree with one another. The evolving states display localized but nonexponential wave function profiles. This provides another route to quantum control in the kicked rotor class of systems.

中文翻译：

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原子光学踢转子中量子扩散和定位之间的相互作用

原子光学踢转子代表了典型的量子踢转子系统的实验可靠版本。在这个系统中，冷原子云会受到周期性的冲击。在短暂的初始扩散阶段之后，由于动态定位的开始，云稳定到静止状态。在本文中，为了探索局部相和扩散相之间的相互作用，我们实验性地对该系统进行了修改，其中踢序列的符号在每$米$踢。在我们的实验中，这是通过在每次之后允许自由进化一半的 Talbot 时间来实现的$米$踢。取决于价值$米$，这个修改后的系统显示了增强扩散和渐近定位的组合。这被解释为由两个相互竞争的过程引起的——由标准反冲转子型反冲引起的定位，以及由半 Talbot 时间演化引起的扩散。实验和数值模拟相互吻合。演化状态显示局部但非指数的波函数剖面。这为踢动转子类系统中的量子控制提供了另一条途径。