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Time-crystalline eigenstate order on a quantum processor.

Abstract:
Quantum many-body systems display rich phase structure in their low-temperature equilibrium states1. However, much of nature is not in thermal equilibrium. Remarkably, it was recently predicted that out-of-equilibrium systems can exhibit novel dynamical phases2-8 that may otherwise be forbidden by equilibrium thermodynamics, a paradigmatic example being the discrete time crystal (DTC)7,9-15. Concretely, dynamical phases can be defined in periodically driven many-body-localized (MBL) systems via the concept of eigenstate order7,16,17. In eigenstate-ordered MBL phases, the entire many-body spectrum exhibits quantum correlations and long-range order, with characteristic signatures in late-time dynamics from all initial states. It is, however, challenging to experimentally distinguish such stable phases from transient phenomena, or from regimes in which the dynamics of a few select states can mask typical behaviour. Here we implement tunable controlled-phase (CPHASE) gates on an array of superconducting qubits to experimentally observe an MBL-DTC and demonstrate its characteristic spatiotemporal response for generic initial states7,9,10. Our work employs a time-reversal protocol to quantify the impact of external decoherence, and leverages quantum typicality to circumvent the exponential cost of densely sampling the eigenspectrum. Furthermore, we locate the phase transition out of the DTC with an experimental finite-size analysis. These results establish a scalable approach to studying non-equilibrium phases of matter on quantum processors.
Publication status:
Published
Peer review status:
Peer reviewed

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Publisher copy:
10.1038/s41586-021-04257-w

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Role:
Author
ORCID:
0000-0003-0507-0211


Publisher:
Springer Nature
Journal:
Nature More from this journal
Volume:
601
Issue:
7894
Pages:
531-536
Place of publication:
England
Publication date:
2021-11-30
Acceptance date:
2021-11-17
DOI:
EISSN:
1476-4687
ISSN:
0028-0836
Pmid:
34847568


Language:
English
Keywords:
Pubs id:
1214344
Local pid:
pubs:1214344
Deposit date:
2022-05-20

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