Experimental control of transport resonances in a coherent quantum rocking ratchet.
Experimental control of transport resonances in a coherent quantum rocking ratchet.
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DOI：
10.1038/ncomms10440
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发表时间：
2016-02-08
影响因子：
16.6
通讯作者：
Weitz M
中科院分区：
文献类型：
--
作者：
Grossert C;Leder M;Denisov S;Hänggi P;Weitz M
棘轮现象是在没有净力的情况下获得定向输运的一种手段。棘轮效应最初是为了纠正随机运动和描述生物马达的工作原理，可用于实现可控相干量子输运。这种传输是包括原子芯片在内的几种透视量子器件的组成部分。在这里，我们研究了超冷原子在摇摆量子棘轮中的相干输运。这是通过将铷原子的玻色-爱因斯坦凝聚体加载到受双调和时间驱动的周期性光势中来实现的。所获得的长时间相干性使我们能够解决系统的Floquet谱中避免交叉引起的原子输运的共振增强。通过调整时间调制的强度，我们观察到单个共振分岔成双态。我们的测量揭示了量子棘轮输运中Floquet本征态之间相互作用的作用。棘轮效应可以作为一种控制超冷原子相干量子输运的工具。在这里，作者用铷BEC展示了一个摇摆量子棘轮，并揭示了量子输运共振的存在。
The ratchet phenomenon is a means to get directed transport without net forces. Originally conceived to rectify stochastic motion and describe operational principles of biological motors, the ratchet effect can be used to achieve controllable coherent quantum transport. This transport is an ingredient of several perspective quantum devices including atomic chips. Here we examine coherent transport of ultra-cold atoms in a rocking quantum ratchet. This is realized by loading a rubidium atomic Bose–Einstein condensate into a periodic optical potential subjected to a biharmonic temporal drive. The achieved long-time coherence allows us to resolve resonance enhancement of the atom transport induced by avoided crossings in the Floquet spectrum of the system. By tuning the strength of the temporal modulations, we observe a bifurcation of a single resonance into a doublet. Our measurements reveal the role of interactions among Floquet eigenstates for quantum ratchet transport. The ratchet effect can be used as a tool to control coherent quantum transport of ultra-cold atoms. Here, the authors demonstrate a rocking quantum ratchet with a rubidium BEC, and reveal the existence of quantum transport resonances.