Changing the order of a dynamical phase transition through fluctuations in a quantum p-spin model

Abstract

We study the non-equilibrium phase diagram of a fully-connected Ising p-spin model, for generic p > 2, and investigate its robustness with respect to the inclusion of spin-wave fluctuations, described by a ferromagnetic, short-range spin interaction. We investigate the dynamics of the mean-field model after a quantum quench observing a new dynamical quantum phase transition which is either first or second order depending on the even or odd parity of p, in stark contrast with the static first order counterpart for all p. In addition, we find that the corresponding phase diagram is qualitatively modified by the fluctuations introduced by a short-range interaction which drive the system always towards various paramagnetic phases distinguished by the strength of time dependent fluctuations of the magnetization.

Floquet time crystals in driven spin systems with all-to-all $p$-body interactions

“…This family of models exhibits a rich and extensively studied variety of critical phenomena [27], including ground state quantum phase transition (GSQPT) between a paramagnetic and a ferromagnetic phase [31], excited state quantum phase transitions (ESQPT) [32] as well as dynamical quantum phase transitions (DQPT) [33,34]. The properties of these phenomena are markedly different depending on the value of p, and in the following we summarize the aspects which are of particular importance to our construction of FTCs.…”