ac Stark shift and multiphoton-like resonances in low-frequency driven optical lattices

TL;DR

This paper explores how Bose-Einstein condensates in optical lattices under ac forcing can reveal multiphoton-like transitions between Bloch bands, with methods to measure and locate these resonances experimentally.

Contribution

It introduces a pulse tracking strategy and demonstrates how to infer resonance widths from asymmetric pulse measurements in optical lattice experiments.

Findings

Resonances correspond to avoided quasienergy crossings.

Width of anticrossings can be measured from asymmetric pulses.

Method applicable to existing experimental setups.

Abstract

We suggest that Bose-Einstein condensates in optical lattices subjected to ac forcing with a smooth envelope may provide detailed experimental access to multiphoton-like transitions between ac-Stark-shifted Bloch bands. Such transitions correspond to resonances described theoretically by avoided quasienergy crossings. We show that the width of such anticrossings can be inferred from measurements involving asymmetric pulses. We also introduce a pulse tracking strategy for locating the particular driving amplitudes for which resonances occur. Our numerical calculations refer to a currently existing experimental set-up [Haller et al., PRL 104, 200403 (2010)].