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 …

Direct observation of zitterbewegung in a Bose–Einstein condensate Read more »

Spin–orbit (SO) coupling—the interaction between a quantum particle’s spin and its momentum—is ubiquitous in physical systems. In condensed matter systems, SO coupling is crucial for the spin-Hall effect and topological insulators; it contributes to the electronic properties of materials such …

Spin-orbit-coupled Bose-Einstein condensates Read more »