Laboratoire de Physique Théorique

de la Matière Condensée

Xhek Turkeshi (Collège de France)

Measurement-induced phase transitions in random circuits

I will discuss what happens to a quantum many-body system when its unitary evolution is interspersed with local measurements. The tension between unitary dynamics (generating entanglement) and measurements (localizing information) resolves in a dynamical phase transition between one phase where dominated by scrambling and another one in which frequent measurements constraint the state on a reduced manifold. In this talk, I will consider the minimal model for the transition, where the unitary dynamics is generated by random circuits. I will discuss how the measurement-induced phase transition is encoded in structural facets of the system wave-function, which is analyzed through the lens of participation entropy. Large-scale numerical simulations and the investigation of a variety of models identify a robust order parameter for the transition.