Controlling directed atomic motion and second-order tunneling of a spin-orbit-coupled atom in optical lattices

TL;DR

This paper investigates how spin-orbit coupling influences tunneling and localization phenomena in a driven optical lattice, revealing new dynamical behaviors and second-order tunneling effects relevant for quantum technologies.

Contribution

It introduces novel dynamical localization and directed motion effects induced by spin-orbit coupling in driven optical lattices, including second-order tunneling between next-nearest neighbors.

Findings

Discovery of a new dynamical localization phenomenon with perfect two-site Rabi oscillation.

Generation of ratchet-like directed atomic motion with spin-flipping.

Identification of spin-conserving second-order tunneling between next-nearest neighbors.

Abstract

We theoretically explore the tunneling dynamics for the tight-binding (TB) 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 new 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 (multi-photon resonances), we obtain an unexpected new 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 inter-site 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 inter-site 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 novel spintronics devices.