Energy and momentum transfer in one-dimensional trapped gases by stimulated light scattering

N Fabbri,M Modugno,S Rosi,M Inguscio,C Fort

doi:10.1088/1367-2630/17/6/063012

Abstract

In ultracold atoms settings, inelastic light scattering is a preeminent technique to reveal static and dynamic properties at nonzero momentum. In this work, we investigate an array of one-dimensional trapped Bose gases, by measuring both the energy and the momentum imparted to the system via light scattering experiments. The measurements are performed in the weak perturbation regime, where these two quantities—the energy and momentum transferred—are expected to be related to the dynamic structure factor of the system. We discuss this relation, with special attention to the role of in-trap dynamics on the transferred momentum.

Highlights

Stimulated scattering of light or particles from condensed-matter systems—solids, liquids, and gases—is a powerful tool for providing fundamental insight into the structure of matter
Inelastic scattering of photons– known as Bragg spectroscopy–has been used to study Bose–Einstein condensates (BECs) in harmonic three-dimensional (3D) traps [3,4,5], quasi-condensates in a quasi one-dimensional (1D) trap [6], BECs in shallow cubic optical lattices [7, 8], strongly interacting BECs across a Feshbach resonance [9], and strongly interacting fermions [10, 11], through direct observation of the net momentum imparted to the system
We have investigated the response of an array of 1D gases, comparing energy and momentum transfer in Bragg spectroscopy experiments

Summary

Introduction

Stimulated scattering of light or particles from condensed-matter systems—solids, liquids, and gases—is a powerful tool for providing fundamental insight into the structure of matter. The quantum phase transition from a superfluid to a Mott-insulator state has been studied in 1D Bose gases in the presence of a longitudinal lattice with experiments of lattice amplitude modulation, where the excitation has zero momentum [12], and with scattering experiments where the excitation has non-zero momentum [13, 14]. The latter technique has been used for studying 1D gases in optical lattices [15, 16]. In the case of deep optical lattices, the energy excess produced by the Bragg perturbation can be measured by lowering the lattice depth, i.e., driving the system in a less interacting regime, and letting it thermalize [12, 13]

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