Report

Roton-Type Mode Softening in a Quantum Gas with Cavity-Mediated Long-Range Interactions

Science  22 Jun 2012:
Vol. 336, Issue 6088, pp. 1570-1573
DOI: 10.1126/science.1220314

You are currently viewing the abstract.

View Full Text
As a service to the community, AAAS/Science has made this article free with registration.

Abstract

Long-range interactions in quantum gases are predicted to give rise to an excitation spectrum of roton character, similar to that observed in superfluid helium. We investigated the excitation spectrum of a Bose-Einstein condensate with cavity-mediated long-range interactions, which couple all particles to each other. Increasing the strength of the interaction leads to a softening of an excitation mode at a finite momentum, preceding a superfluid-to-supersolid phase transition. We used a variant of Bragg spectroscopy to study the mode softening across the phase transition. The measured spectrum was in very good agreement with ab initio calculations and, at the phase transition, a diverging susceptibility was observed. The work paves the way toward quantum simulation of long-range interacting many-body systems.

View Full Text