**Time/Venue **Friday, December 4 at 2:00 pm Pacific Time via this Zoom link:https://berkeley.zoom.us/j/93181359950

**Norman Yao**

Host

Host

**Title**Complexity Transitions in Open Many-Body Systems

**Abstract**Under the environment’s action, open quantum many-body systems are often transitioning into a classical regime described by a polynomial number of parameters and simulable by a classical algorithm. Understanding the conditions of this transition is crucial for quantum computing and classifying open quantum phases. In my talk, I will explore this phenomenon using two different measures: computational hardness and quantum entanglement. I will propose free fermions with quadratic jump operators as a promising candidate for the complexity transition. I also show that, under an anticoncentration assumption, the transition in entanglement in monitored random circuits maps to a disordered classical phase transition.