Dynamical Quantum Phases

Dynamical Quantum Phases

We are familiar with conventional phases of matter such as gas, liquid, and solid, which are equilibrium phases arising from thermodynamic balance. In these cases, the presence of a thermal bath is essential for classical systems to reach thermodynamic equilibrium. A natural question then arises: for a quantum system, is thermodynamic equilibrium defined in the same way as in classical systems, and is a thermal bath required? Moreover, are there systems that, without reaching thermodynamic equilibrium, still exhibit distinctive features of their own? In other words, can we meaningfully speak of dynamical quantum phases that are neither classical equilibrium states nor defined by a thermal bath? In this talk, I will present examples of such quantum systems that demonstrate the emergence of dynamical quantum phases. I will also briefly discuss transitions between different dynamical quantum phases and highlight some practical examples.