Controlling directed atomic motion and second-order tunneling of a spin-orbit-coupled atom in optical lattices
Xiaobing Luo, Zhao‐Yun Zeng, Yu Guo, Baiyuan Yang, Jinpeng Xiao, Lei Li, Chao Kong, Aixi Chen
Abstract
We theoretically explore the tunneling dynamics for the tight-binding model of a single spin-orbit-coupled atom trapped in an optical lattice subjected to lattice shaking and to time-periodic Zeeman field. By means of analytical and numerical methods, we demonstrate that the spin-orbit (SO) coupling adds some results to the tunneling dynamics in both multiphoton resonance and far-off-resonance parameter regimes. When the driving frequency is resonant with the static Zeeman field (multiphoton resonances), we obtain an unexpected dynamical localization (DL) phenomenon where the single SO-coupled atom is restricted to making perfect two-site Rabi oscillation accompanied by spin flipping. By using the unconventional DL phenomenon, we are able to generate a ratchetlike effect which enables directed atomic motion towards different directions and accompanies periodic spin flipping under the action of SO coupling. For the far-off-resonance case, we show that by suppressing the usual intersite tunneling alone, it is possible to realize a type of spin-conserving second-order tunneling between next-nearest-neighboring sites, which is not accessible in the conventional lattice system without SO coupling. We also show that simultaneous controls of the usual intersite tunneling and the SO-coupling-related second-order tunneling are necessary for quasienergies flatness (collapse) and completely frozen dynamics to exist. These results may be relevant to potential applications such as spin-based quantum information processing and design of spintronics devices.