Quantum dynamics in sine-square deformed CFT (CFT in curved space-time) (Sep. 16, 2020)

  • Published: 2020-09-14

Time: 03:00 pm (UTC/GMT+08:00, Beijing/Shanghai), Sep. 16 (Wed.), 2020

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Speaker: Jie-Qiang WU(MIT)



In the standard discussion for quantum system, there are not too many discussions for system without translation invariance. In this work, we discuss a 1+1 dimensional critical system with a sine-square deformed Hamiltonian which breaks the translation invariance. To study the dynamical effect of this system, we consider a quantum quench from the uniform CFT to the sine square deformed CFT. In particular, we compute the entanglement entropy after the quantum quench. We find a cross over time $t^{*}$: before the cross over time the entanglement entropy keeps fixed; after the cross over time the entanglement entropy grows as $\log t$.

This $\log t$ growth with no revival indicates that the sine-squared deformed CFT has an infinite effective length. On the other hand, we find that the sine-square deformed CFT can be described as a CFT on curved space-time, which also supports the infinite effective length observation. 

With the original Hamiltonian and the sine-square deformed Hamiltonian. We can also consider a periodic driving problem. By tuning the driving time, we find the system can have different behavior: heating or non-heating.