Time-of-Flight Roton Spectroscopy in Dipolar Bose-Einstein Condensates

TL;DR

This paper proposes a practical method to detect roton excitations in dipolar Bose-Einstein condensates using lattice perturbations and time-of-flight measurements, supported by numerical simulations.

Contribution

It introduces a simple, experimentally feasible approach to observe roton minima in dipolar BECs through resonant Bragg peak population.

Findings

Roton minima can be detected via resonant Bragg peaks.

The response depends on lattice spacing and scattering length.

Numerical simulations support experimental feasibility.

Abstract

Dipolar Bose-Einstein condensates may present a rotonlike dispersion minimum, which has yet to be observed in experiments. We discuss a simple method to reveal roton excitations, based on the response of quasi-two-dimensional dipolar condensates against a weak lattice potential. By employing numerical simulations for realistic scenarios, we analyze the response of the system as a function of both the lattice spacing and the s-wave scattering length, showing that the roton minimum may be readily revealed in current experiments by the resonant population of Bragg peaks in time-of-flight measurements.