Raman Spectroscopy of Mott insulator states in optical lattices

TL;DR

This paper introduces a Raman spectroscopy method to probe Mott insulator states in optical lattices, focusing on excitations to higher vibrational bands and their dependence on particle number.

Contribution

It develops a formalism for Raman spectroscopy in deep optical lattices, accounting for higher vibrational excitations and localized states in the Mott insulator regime.

Findings

Resonant frequency shifts depend on particle number per site.

The formalism accurately describes excitations in deep lattices.

Numerical results demonstrate the method's effectiveness in Mott insulators.

Abstract

We propose and analyse a Raman spectroscopy technique for probing the properties of quantum degenerate bosons in the ground band of an optical lattice. Our formalism describes excitations to higher vibrational bands and is valid for deep lattices where a tight-binding approach can be applied to the describe the initial state of the system. In sufficiently deep lattices, localized states in higher vibrational bands play an important role in the system response, and shifts in resonant frequency of excitation are sensitive to the number of particles per site. We present numerical results of this formalism applied to the case of a uniform lattice deep in the Mott insulator regime.