Observation of a prethermal discrete time crystal

TL;DR

This paper reports the experimental observation of a prethermal discrete time crystal in a trapped-ion quantum simulator, demonstrating a non-equilibrium phase stabilized by high-frequency driving without disorder.

Contribution

It provides the first experimental evidence of a prethermal discrete time crystal stabilized by high-frequency driving, expanding understanding of non-equilibrium phases of matter.

Findings

Observation of a non-equilibrium time crystal in a controlled quantum system

Drive-frequency dependence of the time crystal's lifetime

Dependence of order on initial energy density

Abstract

The conventional framework for defining and understanding phases of matter requires thermodynamic equilibrium. Extensions to non-equilibrium systems have led to surprising insights into the nature of many-body thermalization and the discovery of novel phases of matter, often catalyzed by driving the system periodically. The inherent heating from such Floquet drives can be tempered by including strong disorder in the system, but this can also mask the generality of non-equilibrium phases. In this work, we utilize a trapped-ion quantum simulator to observe signatures of a non-equilibrium driven phase without disorder: the prethermal discrete time crystal (PDTC). Here, many-body heating is suppressed not by disorder-induced many-body localization, but instead via high-frequency driving, leading to an expansive time window where non-equilibrium phases can emerge. We observe a number of key features that distinguish the PDTC from its many-body-localized disordered counterpart, such as the drive-frequency control of its lifetime and the dependence of time-crystalline order on the energy density of the initial state. Floquet prethermalization is thus presented as a general strategy for creating, stabilizing and studying intrinsically out-of-equilibrium phases of matter.