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2018-01-10 [Invited Talk] Lattice gauge theory in spin systems and emergent dynamics in 1D U(1) quantum link model Dr. Yi-Ping Huang (Max Planck Institute for Physics of Complex Systems, Dresden, Germany)
Title : Lattice gauge theory in spin systems and emergent dynamics in 1D U(1) quantum link model 

Speaker: Dr. Yi-Ping Huang  (Max Planck Institute for Physics of Complex Systems, Dresden, Germany)

Date/Time : January 10, 2018 (Wednesday)/15:00

Venue : SC353 Science Building III, NCTU.

Abstract:
Gauge theory plays a vital role in the development of fundamental physics. The study of gauge structure thus sits at the center of cutting-edge research topics spanning from particle physics, condensed matter physics, and quantum information. Recently, the advances of analog and digital quantum simulators pave another way to understand gauge theories beyond the equilibrium scope. 
 I will start with the first question: how gauge theories emerge as a low energy effective theory in equilibrium? I will discuss this question from a condensed matter perspective. After the discussion in equilibrium, I will switch gear to the non-equilibrium perspective. We study particle-antiparticle production in the quantum quench dynamics after a strong coupling of the bare particles to dynamical gauge field in a quantum link model. We find that for a strong coupling the system experiences dynamical quantum phase transitions (DQPTs) where the vacuum persistence probability (Loschmidt echo) develops non-analytic behavior at critical times. As opposed to the Schwinger mechanism, where matter fields are suddenly coupled to a classical electric field, we observe that the dynamics of the vacuum persistence probability and therefore the DQPTs cannot be understood using the classical picture of particle production. Instead, a quantum dynamical pattern emerges from the strongly coupled matter fields and dynamical gauge fields.