The Higgs mode in a two-dimensional superfluid

TL;DR

This paper provides evidence for a Higgs amplitude mode in a two-dimensional superfluid, using quantum Monte Carlo simulations of the Bose-Hubbard model near the quantum critical point, and discusses its experimental observability.

Contribution

It demonstrates the existence and behavior of the Higgs mode in 2D superfluids through advanced simulations and connects findings to potential cold atom experiments.

Findings

Higgs mode appears as a low-frequency resonance near the critical point

The Higgs mode shifts to high energies and merges with a secondary peak in the superfluid phase

Experimental parameters may obscure the Higgs resonance in cold atom systems

Abstract

We present solid evidence for the existence of a well-defined Higgs amplitude mode in two-dimensional relativistic field theories based on analytically continued results from quantum Monte Carlo simulations of the Bose-Hubbard model in the vicinity of the superfluid-Mott insulator quantum critical point, featuring emergent particle-hole symmetry and Lorentz-invariance. The Higgs boson, seen as a well-defined low-frequency resonance in the spectral density, is quickly pushed to high energies in the superfluid phase and disappears by merging with the broad secondary peak at the characteristic interaction scale. Simulations of a trapped system of ultra-cold $^{87}$Rb atoms demonstrate that the low-frequency resonance feature is lost for typical experimental parameters, while the characteristic frequency for the onset of strong response is preserved.