Our current, well-established understanding of phases of matter primarily relates to systems that are at or near thermal equilibrium. However, there is a rich world of systems that are not in a state of equilibrium, which could host new and fascinating phases of matter.

Recently, studies focusing on systems outside of have led to the discovery of new phases in periodically driven quantum systems, the most well-known of which is the discrete time crystal (DTC) phase. This unique phase is characterized by collective subharmonic oscillations arising from the interplay between many-body interactions and non-equilibrium driving, which leads to a loss of ergodicity.

Interestingly, subharmonic oscillations are also known to be a characteristic of dynamical systems, such as predator-prey models and parametric resonances. Some researchers have thus been exploring the possibility that these may exhibit similar features to those observed in the DTC phase.

Researchers at the University of California have recently carried out a study investigating this possibility, focusing on periodically driven Hamiltonian dynamics coupled to a finite-temperature bath, which can provide both friction and noise. Their paper, recently published in Nature Physics, shows that the noise and interactions arising in this system can drive a first-order dynamical phase transition, from a discrete time-translation invariant phase to an "activated" classical discrete time crystal (CDTC) phase.

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