|12 VI||Piotr Sierant (ICFO, Barcelona, Spain)|
Controlling entanglement at absorbing state phase transitions in random circuitsLocation: MS Teams [ZOA-test], 12:15
I will discuss measurement-induced phase transitions that arise when many-body unitary dynamics is interspersed with repeated measurements. I will focus on the so-called post-selection problem which hinders the possibilities of experimental observation of measurement-induced phase transition and I will discuss our recent attempt  to circumvent this problem. Employing feedback-control operations that steer the dynamics toward an absorbing state, we study the entanglement entropy behavior at the absorbing state phase transition. For short-range control operations, we observe a transition between phases with distinct subextensive scalings of entanglement entropy. In contrast, the system undergoes a transition between volume-law and area-law phases for long-range feedback operations. The fluctuations of entanglement entropy and of the order parameter of the absorbing state transition are fully coupled for sufficiently strongly entangling feedback operations. In that case, entanglement entropy inherits the universal dynamics of the absorbing state transition. This is, however, not the case for arbitrary control operations, and the two transitions are generally distinct. We quantitatively support our results by introducing a framework based on stabilizer circuits with classical flag labels. Our results shed new light on the problem of observability of measurement-induced phase transitions.
 P. Sierant, X. Turkeshi, Phys. Rev. Lett. 130, 120402 (2023)