Time crystals in a shaken atom-cavity system

TL;DR

This paper demonstrates the realization of an incommensurate time crystal in a shaken atom-cavity system, showing persistent nonperiodic oscillations and symmetry-breaking in a driven-dissipative quantum setting.

Contribution

It introduces a novel incommensurate time crystal in a shaken atom-cavity system and analyzes its properties and phase diagram using semiclassical methods.

Findings

Observation of macroscopic oscillations at noninteger multiples of the driving period

Identification of parameter regimes for long-lived time crystal phases

Comparison between incommensurate and commensurate Dicke time crystals

Abstract

We demonstrate the emergence of a time crystal of atoms in a high-finesse optical cavity driven by a phase-modulated transverse pump field, resulting in a shaken lattice. This shaken system exhibits macroscopic oscillations in the number of cavity photons and order parameters at noninteger multiples of the driving period, which signals the appearance of an incommensurate time crystal. The subharmonic oscillatory motion corresponds to dynamical switching between symmetry-broken states, which are nonequilibrium bond ordered density wave states. Employing a semiclassical phase-space representation for the driven-dissipative quantum dynamics, we confirm the rigidity and persistence of the time crystalline phase. We identify experimentally relevant parameter regimes for which the time crystal phase is long-lived, and map out the dynamical phase diagram. We compare and contrast the incommensurate time crystal with the commensurate Dicke time crystal in the amplitude-modulated case.