Topological charge pumping with subwavelength Raman lattices

Abstract

Recent experiments demonstrated deeply subwavelength lattices using atoms with $N$ internal states Raman-coupled with lasers of wavelength $\lambda$. The resulting unit cell was $\lambda /2N$ in extent, an $N$-fold reduction compared to the usual $\lambda /2$ periodicity of an optical lattice. For resonant Raman coupling, this lattice consists of $N$ independent sinusoidal potentials (with period $\lambda /2$) displaced by $\lambda /2N$ from each other. We show that detuning from Raman resonance induces tunneling between these potentials. Periodically modulating the detuning couples the $s$- and $p$-bands of the potentials, creating a pair of coupled subwavelength Rice--Mele chains. This operates as a novel topological charge pump that counter-intuitively can give half the displacement per pump cycle of each individual Rice--Mele chain separately. We analytically describe this behavior in terms of infinite-system Chern numbers, and numerically identify the associated finite-system edge states.

12 pages, 8 figures

References in corpus (7)

• Nearly-flat bands with nontrivial topology
• Nano-Scale `Dark State' Optical Potentials for Cold Atoms
• Subwavelength-width optical tunnel junctions for ultracold atoms
• Atoms in a radiofrequency-dressed optical lattice
• Splitting of topological charge pumping in an interacting two-component fermionic Rice-Mele Hubbard model
• Bloch oscillations of atoms in an optical multiphoton potential
• Observations of $\lambda /4$ structure in a low-loss radiofrequency-dressed optical lattice

Cited by in corpus (3)

• Many-body phases from effective geometrical frustration and long-range interactions in a subwavelength lattice
• Geometric Quantum Gates of Non-closed Paths Under Counterdiabatic Driving
• Magnetically generated spin-orbit coupling for ultracold atoms with slowly varying periodic driving