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arXiv 1802.07765cond-mat.str-elhep-th
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正弦平方形变共形场论中的量子动力学:从均匀到非均匀CFTs的猝灭

Quantum dynamics in sine-square deformed conformal field theory: Quench from uniform to non-uniform CFTs

Xueda Wen, Jie-Qiang Wu

摘要:

本文以(1+1)维量子临界系统的正弦平方形变(SSD)为出发点,研究了具有连续能谱和连续Virasoro代数的具有SSD的共形场论(CFT)的非平衡量子动力学.特别地,我们研究了量子猝灭后纠缠熵的时间演化,从一个均匀的CFT,这是定义在一个有限的空间长度$L$,正弦平方变形的CFT。我们发现存在一个交叉时间$t^{\ast}$,它将纠缠演化分为两个有趣的区域。对于$t\ll t^{\ast}$,纠缠熵不随时间演化;对于$t\gg t^{\ast}$,纠缠熵以$S_A(t)\simeq \frac{c}{3}\log t$的形式增长,与子系统和整个系统的长度无关。这$\log t$增长没有复苏表明,正弦平方变形CFT有效地具有无限长,与以前的研究的基础上的能谱分析。此外,我们研究了具有M $\ddot{\text{o}}$ bius变形的CFT的淬火动力学,该变形介于均匀CFT和正弦平方变形CFT之间。纠缠熵随时间以周期$L_{\text{eff}}=L\cosh(2θ)$振荡,其中$θ=0$对应于均匀情况,而$θ\to \infty$对应于SSD极限。对(1+1)维临界费米子链的数值研究证实了我们的场论计算。

英文摘要:

In this work, motivated by the sine-square deformation (SSD) for (1+1)-dimensional quantum critical systems, we study the non-equilibrium quantum dynamics of a conformal field theory (CFT) with SSD, which was recently proposed to have continuous energy spectrum and continuous Virasoro algebra. In particular, we study the time evolution of entanglement entropy after a quantum quench from a uniform CFT, which is defined on a finite space of length $L$, to a sine-square deformed CFT. We find there is a crossover time $t^{\ast}$ that divides the entanglement evolution into two interesting regions. For $t\ll t^{\ast}$, the entanglement entropy does not evolve in time; for $t\gg t^{\ast}$, the entanglement entropy grows as $S_A(t)\simeq \frac{c}{3}\log t$, which is independent of the lengths of the subsystem and the total system. This $\log t$ growth with no revival indicates that a sine-square deformed CFT effectively has an infinite length, in agreement with previous studies based on the energy spectrum analysis. Furthermore, we study the quench dynamics for a CFT with M$\ddot{\text{o}}$bius deformation, which interpolates between a uniform CFT and a sine-square deformed CFT. The entanglement entropy oscillates in time with period $L_{\text{eff}}=L\cosh(2θ)$, with $θ=0$ corresponding to the uniform case and $θ\to \infty$ corresponding to the SSD limit. Our field theory calculation is confirmed by a numerical study on a (1+1)-d critical fermion chain.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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