Fractional photon-assisted tunneling in an optical superlattice: large contribution to particle transfer

TL;DR

This paper investigates fractional photon-assisted tunneling in ultra-cold atoms within optical superlattices, introducing an effective model that accurately predicts large particle transfer effects at specific resonances, validated by numerical and analytical methods.

Contribution

It presents a new effective model based on the rotating wave approximation that surpasses previous perturbation theories for analyzing fractional photon-assisted tunneling.

Findings

Large effects observed at one-half-photon and one-third-photon resonances.

The effective model accurately predicts particle transfer dynamics.

Good agreement between analytical results and numerical simulations.

Abstract

Fractional photon-assisted tunneling is investigated both analytically and numerically for few interacting ultra-cold atoms in the double-wells of an optical superlattice. This can be realized experimentally by adding periodic shaking to an existing experimental setup [Phys. Rev. Lett. 101, 090404 (2008)]. Photon-assisted tunneling is visible in the particle transfer between the wells of the individual double wells. In order to understand the physics of the photon-assisted tunneling, an effective model based on the rotating wave approximation is introduced. The validity of this effective approach is tested for wide parameter ranges which are accessible to experiments in double-well lattices. The effective model goes well beyond previous perturbation theory approaches and is useful to investigate in particular the fractional photon-assisted tunneling resonances. Analytic results on the level of the experimentally realizable two-particle quantum dynamics show very good agreement with the numerical solution of the time-dependent Schr\"odinger equation. Far from being a small effect, both the one-half-photon and the one-third-photon resonance are shown to have large effects on the particle transfer.