Novel 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 thermalisation, 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.

A/Prof Stephan Rachel is an ARC Future Fellow and leader of the Correlations and Topology in Condensed Matter group in the School of Physics at the University of Melbourne. His interests range from superconductors and quantum magnets to quantum computing.