Fakultät für Physik, Ludwig-Maximilians-Universität, München, Germany.
Phys Rev Lett. 2011 Nov 18;107(21):210405. doi: 10.1103/PhysRevLett.107.210405.
The dynamical control of tunneling processes of single particles plays a major role in science ranging from Shapiro steps in Josephson junctions to the control of chemical reactions via light in molecules. Here we show how such control can be extended to the regime of correlated tunneling of strongly interacting particles. Through a periodic modulation of a biased tunnel contact, we have been able to coherently control single-particle and correlated two-particle hopping processes. We have furthermore been able to extend this control to superexchange spin interactions in the presence of a magnetic-field gradient. Such photon-assisted superexchange processes constitute a novel approach to realize arbitrary XXZ spin models in ultracold quantum gases, where transverse and Ising-type spin couplings can be fully controlled in magnitude and sign.
单粒子隧道过程的动力学控制在科学中起着重要作用，范围从约瑟夫森结中的 Shapiro 台阶到通过分子中的光控制化学反应。在这里，我们展示了如何将这种控制扩展到强相互作用粒子相关隧道的范围。通过对偏置隧道接触进行周期性调制，我们能够相干地控制单粒子和相关的两粒子跳跃过程。此外，我们还能够将这种控制扩展到存在磁场梯度时的超交换自旋相互作用。这种光子辅助的超交换过程为在超冷量子气体中实现任意 XXZ 自旋模型提供了一种新方法，其中横向和 Ising 型自旋耦合可以在幅度和符号上完全控制。
