Light cone dynamics and reverse Kibble-Zurek mechanism in two-dimensional superfluids following a quantum quench
Light cone dynamics and reverse Kibble-Zurek mechanism in two-dimensional superfluids following a quantum quench
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量子淬灭后二维超流体中的光锥动力学和反向 Kibble-Zurek 机制
DOI：
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发表时间：
2009
期刊：
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通讯作者：
A. Polkovnikov
中科院分区：
文献类型：
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作者：
L. Mathey;A. Polkovnikov
我们研究了两种超流体解耦后双层二维超流体的相对相的动力学。我们发现，在短时间尺度上，相对位相呈现出“光锥”式的动力学，并产生一种亚稳态的超流态，这可能是超临界的。我们也为横场伊辛模型演示了类似的光锥动力学。在较长的时间尺度上，由于动力学涡旋解束缚，超临界状态弛豫到无序状态。这种动态抑制涡旋扩散的情景构成了反向Kibble-Zurek效应。我们用截断的Wigner近似和新提出的含时重整化群方法(RG)，用数值方法和解析方法研究了这种效应。特别地，在RG中，我们证明了对应于超流体和正常稳态的实时演化存在两个可能的固定点。因此，依赖于初始条件和哈密顿量的微观参数，系统经历了Kosterlitz-Thouless类型的非平衡相变。在临界点附近，旋涡解绑的时间尺度呈指数发散，类似于平衡情况。
We study the dynamics of the relative phase of a bilayer of two-dimensional superfluids after the two superfluids have been decoupled. We find that on short time scales the relative phase shows 'light cone'-like dynamics and creates a metastable superfluid state, which can be supercritical. We also demonstrate similar light cone dynamics for the transverse field Ising model. On longer time scales the supercritical state relaxes to a disordered state due to dynamical vortex unbinding. This scenario of dynamically suppressed vortex proliferation constitutes a reverse-Kibble-Zurek effect. We study this effect both numerically using truncated Wigner approximation and analytically within a newly suggested time dependent renormalization group approach (RG). In particular, within RG we show that there are two possible fixed points for the real-time evolution corresponding to the superfluid and normal steady states. So depending on the initial conditions and the microscopic parameters of the Hamiltonian the system undergoes a nonequilibrium phase transition of the Kosterlitz-Thouless type. The time scales for the vortex unbinding near the critical point are exponentially divergent, similar to the equilibrium case.