Observing dynamical currents in a non-Hermitian momentum lattice

TL;DR

This paper demonstrates the experimental observation of dynamical currents in a non-Hermitian momentum lattice using a spinor Bose-Einstein condensate and cavity-assisted Raman scattering, revealing superradiant tunneling and potential for dynamical gauge fields.

Contribution

The study presents the first experimental realization of dynamical currents in a non-Hermitian momentum lattice with real-time detection, advancing understanding of driven-dissipative quantum systems.

Findings

Observation of superradiant tunneling events

Real-time, frequency-resolved detection of cavity leaks

Potential to realize dynamical gauge fields

Abstract

We report on the experimental realization and detection of dynamical currents in a spin-textured lattice in momentum space. Collective tunneling is implemented via cavity-assisted Raman scattering of photons by a spinor Bose-Einstein condensate into an optical cavity. The photon field inducing the tunneling processes is subject to cavity dissipation, resulting in effective directional dynamics in a non-Hermitian setting. We observe that the individual tunneling events are superradiant in nature and locally resolve them in the lattice by performing real-time, frequency-resolved measurements of the leaking cavity field. The results can be extended to a regime exhibiting a cascade of currents and simultaneous coherences between multiple lattice sites, where numerical simulations provide further understanding of the dynamics. Our observations showcase dynamical tunneling in momentum-space lattices and provide prospects to realize dynamical gauge fields in driven-dissipative settings.