Collective modes of a strongly interacting Bose gas: probing the Mott transition

TL;DR

This study investigates the collective excitations of a strongly interacting Bose gas near the Mott transition, revealing dimension-dependent behaviors of modes that can inform experimental detection of quantum phase changes.

Contribution

It introduces a dynamical Gutzwiller approach to analyze collective modes near the Mott transition across different spatial dimensions.

Findings

Dipole mode frequency vanishes at the transition in 1D

Higher dimensions show no dipole mode signature

Breathing mode reveals transition in higher dimensions

Abstract

We analyze the collective modes of a harmonically trapped, strongly interacting Bose gas in an optical lattice in the vicinity of the Mott insulator transition. For that aim we employ the dynamical Gutzwiller equations, by performing real-time evolution and by solving the equations in linear response. We find a strong dependence on the spatial dimension of the system: while in one dimension the frequency of the dipole mode vanishes at the Mott transition, in higher dimensions the dominant dipole mode is featureless and we find a signature only in the breathing mode. We discuss implications for experiments with bosonic and fermionic atoms.