Regular Article

Periodic driving induced helical Floquet channels with ultracold atoms in momentum space^⋆

¹ Interdisciplinary Center of Quantum Information, State Key Laboratory of Modern Optical Instrumentation, and Zhejiang Province Key Laboratory of Quantum Technology and Device of Physics Department, Zhejiang University, Hangzhou 310027 P.R. China
² Institute for Advanced Study, Tsinghua University, Beijing 100084, P.R. China
³ CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, P.R. China
⁴ CAS Center For Excellence in Quantum Information and Quantum Physics, Hefei 230026, P.R. China

^a e-mail: yanbohang@zju.edu.cn

Received: 10 January 2020
Received in final form: 8 May 2020
Published online: 7 July 2020

Abstract

Employing the external degrees of freedom of atoms as synthetic dimensions renders easy and new accesses to quantum engineering and quantum simulation. As a recent development, ultracold atoms suffering from two-photon Bragg transitions can be diffracted into a series of discrete momentum states to form a momentum lattice. Here we provide a detailed analysis on such a system, and, as a concrete example, report the observation of robust helical Floquet channels, by introducing periodic driving sequences. The robustness of these channels against perturbations is confirmed, as a test for their topological origin captured by Floquet winding numbers. The periodic switching demonstrated here serves as a testbed for more complicated Floquet engieering schemes, and offers exciting opportunities to study novel topological physics in a many-body setting with tunable interactions.