Fast phase-modulated optical lattice for wave packet engineering

TL;DR

This paper demonstrates how high-frequency phase modulation of a 1D optical lattice can precisely control the potential depth of a Bose-Einstein condensate, enabling advanced wave packet engineering and out-of-equilibrium studies.

Contribution

It experimentally verifies the Bessel-function dependence of the lattice depth on modulation amplitude and applies this to perform precise phase shifts and dynamic studies.

Findings

Renormalization of lattice depth by a Bessel function

Successful implementation of a $ ext{-phase shift}

Observation of out-of-equilibrium dynamics

Abstract

We investigate experimentally a Bose Einstein condensate placed in a 1D optical lattice whose phase is modulated at a frequency large compared to all characteristic frequencies. As a result, the depth of the periodic potential is renormalized by a Bessel function which only depends on the amplitude of modulation, a prediction that we have checked quantitatively using a careful calibration scheme. This renormalization provides an interesting tool to engineer in time optical lattices. For instance, we have used it to perform simultaneously a sudden $\pi$-phase shift (without phase residual errors) combined with a change of lattice depth, and to study the subsequent out-of-equilibrium dynamics.