An international team of physicists has shown that novel non-equilibrium phases of matter — called prethermal discrete time crystals (DTCs) — can emerge in classical dynamics and do not depend on quantum mechanics. This makes large simulations with relevance to experiments possible.
DTCs generalize the notion of phase of matter to the non-equilibrium realm. They break the discrete time-translational symmetry of a periodic drive by responding at a subharmonic of that frequency. Among the declinations of time-crystalline phenomena that have been investigated recent years, discrete time-symmetry breaking in prethermal DTCs lasts for a finite but very long time (exponential in drive frequency). Discovered in a quantum-mechanical setting, analyzing prethermal DTCs has so far remained challenging to due to the notorious complexity of quantum many-body systems.
In a double publication, the team of physicists from Cambridge, TU Munich, and Nottingham (now at the University of Vienna) show that prethermal DTCs can be captured by a classical theory that has virtually no numerical limitations. With large-scale numerical simulations, the authors provide the up-to-date clearest portrait of these phenomena, e.g. the first instance of a prethermal DTC with short-range interactions in three dimensions and scenarios of prime relevance for experiments.
These two works establish classical Hamiltonian dynamics as an approach to large-scale simulations of prethermal phases of matter, thereby remove the stringent constraints for quantum many-body simulations, and open new avenues in the growing field of non-equilibrium many-body dynamics.
Reference: “Classical Prethermal Phases of Matter” by Andrea Pizzi, Andreas Nunnenkamp and Johannes Knolle, 27 September 2021, Physical Review Letters.