Realization of a discrete time crystal on 57 qubits of a quantum computer

• Published in: Science advances Vol. 8; no. 9; p. eabm7652
• Main Authors: Frey, Philipp, Rachel, Stephan
• Format: Journal Article
• Language: English
• Published: United States American Association for the Advancement of Science 04.03.2022
• Subjects: Condensed Matter Physics; Physical and Materials Sciences; Physics; SciAdv r-articles
• ISSN: 2375-2548; 2375-2548
• DOI: 10.1126/sciadv.abm7652

Unconventional dynamical phases that violate ergodicity have been a subject of extensive research in recent years. A periodically driven system is naively expected to lose all memory of its initial state due to thermalization, yet this can be avoided in the presence of many-body localization. A discrete time crystal represents a driven system whose local observables spontaneously break time translation symmetry and retain memory of the initial state indefinitely. Here, we report the observation of a discrete time crystal on a chain consisting of 57 superconducting qubits on a state-of-the-art quantum computer. We probe random initial states and compare the cases of vanishing and finite disorder to distinguish many-body localization from prethermal dynamics. We further report results on the dynamical phase transition between the discrete time crystal and a thermal regime, which is observed via critical fluctuations in the system’s subharmonic frequency response and a substantial speedup of spin depolarization. The time crystal phase has been observed, and a first step toward establishing a dynamical phase diagram has been obtained.