Solid-state continuous time crystal with a built-in clock

TL;DR

This paper demonstrates a solid-state continuous time crystal using microcavity exciton-polaritons, showing controllable phases and establishing a new platform for studying time-broken symmetry in non-Hermitian systems.

Contribution

It introduces a novel realization of a time crystal with microcavity polaritons, controlled by optical drive power and phonon interactions, expanding the understanding of time-broken symmetry.

Findings

Observation of Larmor precession as a signature of continuous TC

Frequency locking of precession to coherent phonons for stabilized TC

Doubling of TC frequency via phonons indicating a discrete TC

Abstract

Time crystals (TCs) are many-body systems displaying spontaneous breaking of time translation symmetry. Here, we demonstrate a TC using driven-dissipative condensates of microcavity exciton-polaritons, spontaneously formed from an incoherent particle bath. In contrast to other realizations, the TC phases can be controlled by the power of continuous-wave non-resonant optical drive exciting the condensate and optomechanical interactions with phonons. Those phases are for increasing power: (i) Larmor precession of pseudo-spins - a signature of continuous TC, (ii) locking of the frequency of precession to self-sustained coherent phonons - stabilized TC, (iii) doubling of TC frequency by phonons - a discrete TC with continuous excitation. These results establish microcavity polaritons as a platform for the investigation of time-broken symmetry in non-hermitian systems.