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Quantum Materials Seminar co-organized with QIQB, Osaka University: Taming Quantum Entanglement

Date : Thursday, March 28th, 2019 4:00 pm - 5:00 pm Place : Seminar Room 5 (A615), 6th Floor, ISSP Lecturer : Prof. Matthew P. A. Fisher Affiliation : University of California, Santa Barbara Committee Chair : Masaki Oshikawa (63275)
e-mail: oshikawa@issp.u-tokyo.ac.jp

Non-local quantum entanglement – “spooky action at a distance” – is the key feature that distinguishes quantum from classical systems. The entanglement-entropy provides a measure of entanglement and for many-body systems is intimately connected to the thermal-entropy. Out of equilibrium, in a driven system or after a quantum quench, entanglement spreads ballistically with maximal entropy attained at long times – that is, complete disorder reigns. But not (always!) with life on earth! Why? In this talk I will discuss several different mechanisms to tame entanglement growth;
(i) by quenched disorder in systems exhibiting many-body localization,
(ii) by coupling light quantum particles to heavy (almost classical) particles, and
(iii) by “looking repeatedly” at the system (i.e. making projective measurements)-a many-body quantum Zeno effect.
In the latter case, I will explore a novel hybrid quantum circuit model consisting of both unitary gates and projective measurements, presenting evidence for a new quantum dynamical phase transition between a weak measurement phase and a quantum Zeno phase. Detailed steady-state and dynamic critical properties of this novel quantum entanglement transition will be described.


(Published on: Wednesday March 20th, 2019)