The role of fluctuations in quantum and classical time crystals

Abstract

Discrete time crystals (DTCs) are a many-body state of matter whose dynamics are slower than the forces acting on it. The same is true for classical systems with period-doubling bifurcations. Hence, the question naturally arises what differentiates classical from quantum DTCs. Here, we analyze a variant of the Bose-Hubbard model, which describes a plethora of physical phenomena and has both a classical and a quantum time-crystalline limit. We study the role of fluctuations on the stability of the system and find no distinction between quantum and classical DTCs. This allows us to probe the fluctuations in an experiment using two strongly coupled parametric resonators subject to classical noise.

Discrete time translation symmetry breaking in a Josephson junction laser

“…The breaking of a DTTS has been studied extensively elsewhere in the context of many-body systems of coupled oscillators and the symmetry broken time-crystalline phases that emerge [13][14][15][16][17]. For superconducting circuits, although attention has largely focused on systems where just one or two modes play an important role, the possibilities enabled by utilising multiple modes are attracting increasing attention [18].…”