arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1811.02493quant-phcond-mat.stat-mechcond-mat.str-el
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猝灭动力学和零能模:Creutz模型的情况

Quench dynamics and zero-energy modes: the case of the Creutz model

R. Jafari, Henrik Johannesson, A. Langari, M. A. Martin-Delgado

摘要:

在大多数晶格模型中,带隙的闭合通常发生在布里渊区中的高对称点处。相应地,在描述无自旋费米子在被磁场$-$穿透的两条腿梯子上跳跃的Creutz模型$-$中,在模型的两个拓扑非平凡相之间的量子相变处闭合的能隙可以通过调节跳跃幅度来移动。我们利用这一属性来检查模型的非平衡动力学后,突然淬火的磁通量通过plaquettes的阶梯。对于淬火的平衡量子临界点之一,我们发现,恢复周期的Loschelles回声$-$测量初始和时间演化状态之间的重叠$-$是由关闭零能量模式的间隙控制。特别是,与预期相反,复活期的Loschirst回声有限的梯子不成线性比例的大小,但表现出跳跃的存在或不存在的零能量模式。我们进一步研究了该模型中出现动态量子相变的条件,发现对于猝灭{ \em到}平衡临界点,这种相变只发生在具有零能量模式的梯子上。利用量子热力学的概念,我们表明,平均工作和不可逆的工作,每个晶格位置表现出弱依赖于系统的大小后,淬火{ \em跨越}的平衡临界点,这表明淬火成不同的阶段诱导有效的粒子之间的相关性。

英文摘要:

In most lattice models, the closing of a band gap typically occurs at high-symmetry points in the Brillouin zone. Differently, in the Creutz model $-$ describing a system of spinless fermions hopping on a two-leg ladder pierced by a magnetic field $-$ the gap closing at the quantum phase transition between the two topologically nontrivial phases of the model can be moved by tuning the hopping amplitudes. We take advantage of this property to examine the nonequilibrium dynamics of the model after a sudden quench of the magnetic flux through the plaquettes of the ladder. For a quench to one of the equilibrium quantum critical points we find that the revival period of the Loschmidt echo $-$ measuring the overlap between initial and time-evolved states $-$ is controlled by the gap closing zero-energy modes. In particular, and contrary to expectations, the revival period of the Loschmidt echo for a finite ladder does not scale linearly with size but exhibits jumps determined by the presence or absence of zero-energy modes. We further investigate the conditions for the appearance of dynamical quantum phase transitions in the model and find that, for a quench {\em to} an equilibrium critical point, such transitions occur only for ladders of sizes which host zero-energy modes. Exploiting concepts from quantum thermodynamics, we show that the average work and the irreversible work per lattice site exhibit a weak dependence on the size of the system after a quench {\em across} an equilibrium critical point, suggesting that quenching into a different phase induces effective correlations among the particles.

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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