Exploring multi-band excitations of interacting Bose gases in a 1D optical lattice by coherent scattering

TL;DR

This paper demonstrates a coherent scattering technique to probe multi-band excitations in interacting Bose gases within a 1D optical lattice, revealing interaction effects across various lattice depths.

Contribution

It introduces a novel coherent Bragg diffraction method to measure multi-band excitation spectra in ultracold Bose gases in a 1D lattice.

Findings

Oscillatory momentum behavior observed in experiments.

Extraction of multi-band energy structures from oscillation frequencies.

Interaction effects evident across different lattice depths.

Abstract

We use a coherent Bragg diffraction method to impart an external momentum to ultracold bosonic atoms trapped in a one-dimensional optical lattice. This method is based on the application of a single light pulse, with conditions where scattering of photons can be resonantly amplified by the atomic density grating. An oscillatory behavior of the momentum distribution resulting from the time evolution in the lattice potential is then observed. By measuring the oscillating frequencies, we extract multi-band energy structures of single-particle excitations with zero pseudo-momentum transfer for a wide range of lattice depths. The excitation energy structures reveal the interaction effect through the whole range of lattice depth.