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Research Highlights

Classical approaches to prethermal discrete time crystals

Andrea Pizzi, Andreas Nunnenkamp, and Johannes Knolle.

A team of current and former TCM researchers uses a 'back-to-basics' classical theory to shed light on prethermal discrete time crystals (DTCs). Previously believed a quantum phenomenon, this collective behavior is now showed to also emerge in classical Hamiltonian (nondissipative) dynamics.

A classical theory captures prethermal DTCs in high-dimensional lattices with short- to long-range interactions, in which discrete time translational symmetry is broken for a time increasing with the dive frequency.

DTCs are exotic behaviours that generalize the notion of phase of matter to the nonequilibrum realm, breaking the discrete time translational symmetry of a periodic drive responding at a submultiple frequency of that of the drive. Among the various declinations of time crystalline phenomena that have been investigated in recent years, particularly relevant are prethermal DTCs, in which the discrete time symmetry breaking lasts for a finite but exceptionally long (exponential in drive frequency) time. Discovered within a quantum formalism, these phenomena have remained pretty elusive due to the notorious complexity and numerical limitations of quantum many-body theories.

In a double publication, the authors show that prethermal DTCs are captured in essentially the same way by a classical theory, with the advantage that virtually any numerical limitation is lifted in the latter. Opening the way towards large scale simulations of nonequilibrium many-body systems, the authors could provide the clearest portrait of these phenomena, e.g., by showing the first instance of a prethermal DTC with short-range interactions in three dimensions, and accessing other scenarios of prime relevance for experiments.

This research establishes classical Hamiltonian dynamics as a suitable approach to large-scale simulations of prethermal phases of matter and, removing the stringent constraints of simulating quantum many-body systems, opens new avenues in the rapidly growing field of non-equilibrium many-body dynamics.

Pizzi, A., Nunnenkamp, A., and Knolle, J., "Classical Prethermal Phases of Matter." Physical Review Letters 127, 140602 (2021).

Pizzi, A., Nunnenkamp, A., and Knolle, J., "Classical approaches to discrete time crystals in one, two, and three dimensions." Physical Review B 104, 094308 (2021).

Text readapted from Cambridge Research News. The two papers are featured in Physics.
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