A reminder that we will meet in room 6-310 at 11am for our group meeting, where David Shukur will tell us about quasiprobabilities, and then at 1:30pm we will have a talk in 6C-442 by Soonwon Choi (info below).

---

Soonwon Choi, Berkeley
Friday, February 7. 1:30 pm.  6C-442 (Cosman Room)
Title: Phase transitions in the dynamics of quantum information

Abstract:
Quantum information science seeks to understand and control quantum systems with high entanglement and complexity, defining a new frontier of physics. In this talk, we discuss a novel phenomenon that arises in this regime: a phase transition in the dynamics of quantum entanglement and information. We consider a generic quantum many-body system coupled to a noisy environment, which we model with random unitary circuits interspersed by projective measurements. The interplay between unitary evolution and measurements leads to a phase transition: at high measurement rates, any coherent information in the system is completely lost, while at sufficiently low rates, an extensive amount of information is robustly protected. The nature of the phase transition can be understood from two complementary perspectives: firstly, by using the quantum error-correcting properties of scrambling unitary dynamics; and secondly, by using a mapping to ordering transitions in classical statistical mechanics. The implications of our work for on-going experiments as well as for broad future research directions will be discussed.