Fractional photon-assisted tunnelling of ultra-cold atoms in periodically shaken double-well lattices

TL;DR

This paper explores fractional photon-assisted tunnelling in ultra-cold atoms within double-well lattices, highlighting its many-body nature and potential observability at specific resonances.

Contribution

It introduces the concept of fractional photon-assisted tunnelling as an interaction-driven many-body phenomenon and predicts the 1/4-resonance in few-particle double-well systems.

Findings

Fractional photon-assisted tunnelling is a many-body effect distinct from single-particle tunnelling.

The 1/4-resonance can be observed in systems with few particles per double well.

Higher-order perturbation theory reveals large contributions despite small lower-order terms.

Abstract

Fractional photon-assisted tunnelling is investigated both numerically and analytically in a double-well lattice. While integer photon-assisted tunnelling is a single-particle effect, fractional photon-assisted tunnelling is an interaction-induced many-body effect. Double-well lattices with few particles in each double well are ideal to study this effect far from the mean-field effects. It is predicted that the 1/4-resonance is observable in such systems. Fractional photon-assisted tunnelling provides a physically relevant model for which N-th order time-dependent perturbation theory can be large although all previous orders are small.