Observing Quantum Phase Transitions in a Moving Frame

by Prof. Jinwu Ye (Mississippi State University)

Friday 17 Sept 2021, 10:00 → 11:00 Asia/Shanghai

TDLI Meeting Room 200

Abstract

Quantum phase transitions are among the most fantastic phenomena in Nature. Here we show that observing them in different inertial frames may lead to dramatically different phenomena. Specifically, we observe two kinds of 2d Superfluid-Mott transitions in a square lattice in a lab frame where the lattice is at rest and in a frame moving with a constant velocity cc.

(1) the first one has the dynamic exponent z=1z=1, the particle-hole (PH) symmetry, and an emergent Lorentz invariance,

(2) the second one has the dynamic exponent z=2z=2,  without the PH symmetr ,and an emergent Galileo invariance.

Counter-intuitively, if a state is a Mott insulating state or a dissipation-less SF state depends on if the observer is in the lab frame or in the moving frame. Field theory renormalization group analysis are performed to study the universality classes of these novel quantum phase transitions in the moving frame. Finite temperature properties of quantum or classical scaling functions of various physical quantities, especially their dependencies on the velocity cc are explored. The intrinsic interplay between the symmetry breaking and the Galileo transformation are analyzed. Charge- vortex duality transformations are also performed  to study these new quantum phase transitions in the moving frame. Crucial differences with an object moving in a superfluid or a flowing superfluid with a constant velocity are discussed. The methods can be extended to all the quantum or topological phase transitions in any dimension. Doing measurements in a moving frame becomes a easy and effective way to tune various quantum and topological phases and phase transitions. Experimental realizations and detections are also discussed.

Biography

叶锦武教授是美国耶鲁大学理论物理博士。他现在是美国密西西比州立大学教授. He has been a long term visitor at T D Lee Institute.

叶教授主要研究领域是强相互作用的电子, 玻色子, 自旋，光子等的合作现象和量子或拓扑相变理论,

他的研究还涉及超对称性破缺，共形场论和各种量子或拓扑相的量子引力对偶.

His two most recent research directions are on

(1) Topological Phases,topological phase transitions driven by interactions in various spin-orbit coupled systems.

(2) Quantum chaos and quantum information scramblings in cavity QED systems or in Sachdev-Ye-Kitaev (SYK) models. Connections among SYK models, conformal field theory and topological phases.

Division

Condensed Matter

Other information

Tencent /Voov Meeting Link: https://meeting.tencent.com/dm/wRuFEqbDWICK
Meeting ID: 914 863 048                                          Password: 123456