Disordered monitored free fermions

Abstract

Scrambling of quantum information in unitary evolution can be hindered due to measurements and localization, which pin quantum mechanical wave functions in real space, suppressing entanglement in the steady state. In monitored free-fermionic models, the steady state undergoes an entanglement transition from a logarithmically entangled critical state to area law. However, disorder can lead to Anderson localization. We investigate free fermions in a random potential with continuous monitoring, which enables us to probe the interplay between measurement-induced and localized phases. We show that the critical phase is stable up to a finite disorder, and the criticality is consistent with the Berezinskii-Kosterlitz-Thouless universality. Furthermore, monitoring destroys localization, and the area-law phase at weak dissipation exhibits power-law decay of single-particle wave functions. Our work opens an avenue to probe this phase transition in electronic systems of quantum dot arrays and nanowires and allow quantum control of entangled states.