Direct observation of zitterbewegung in a Bose-Einstein condensate

TL;DR

This paper reports the first direct observation of zitterbewegung, a trembling motion predicted for relativistic particles, by simulating the Dirac equation in a Bose-Einstein condensate of rubidium atoms.

Contribution

It demonstrates how ultracold quantum gases can be engineered to simulate relativistic quantum phenomena like zitterbewegung.

Findings

Direct imaging of trembling motion in BECs

Simulation of Dirac equation with neutral atoms

Observation of relativistic effects in ultracold gases

Abstract

Zitterbewegung, a force-free trembling motion first predicted for relativistic fermions like electrons, was an unexpected consequence of the Dirac equation's unification of quantum mechanics and special relativity. Though the oscillatory motion's large frequency and small amplitude have precluded its measurement with electrons, zitterbewegung is observable via quantum simulation. We engineered an environment for 87Rb Bose-Einstein condensates where the constituent atoms behaved like relativistic particles subject to the one-dimensional Dirac equation. With direct imaging, we observed the sub-micrometer trembling motion of these clouds, demonstrating the utility of neutral ultracold quantum gases for simulating Dirac particles.