Environment-assisted discrete time crystals in noninteracting quantum systems
Phys. Rev. A 113, 042216 – Published 16 April, 2026
DOI: https://doi.org/10.1103/kf54-gtvj
Abstract
A discrete time crystal (DTC) is an out-of-equilibrium phase of quantum matter that exhibits broken discrete time-translation symmetry, manifested through a robust subharmonic response to periodic driving. Such phases are of interest for quantum memory and fault-tolerant quantum operations. However, conventional DTCs are typically fragile in the presence of environmental dissipation. Here, we propose and experimentally demonstrate a DTC phase in a noninteracting system whose stability is instead enabled by environmental decoherence. The lifetime of this DTC is independent of the initial state and system size, while exhibiting a nontrivial dependence on the driving frequency. Using nuclear magnetic resonance spectroscopy, we realize this phase experimentally and find excellent agreement with theoretical predictions. This environment-assisted discrete time crystal represents a distinct nonequilibrium phase, naturally described within a Liouvillian framework, and offers a promising route toward robust time-crystalline behavior in open quantum systems.
