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首页> 外文期刊>Physical review >Defect Generation In A Spin-1/2 Transverse Xy Chain Under Repeated Quenchingrnof The Transverse Field
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Defect Generation In A Spin-1/2 Transverse Xy Chain Under Repeated Quenchingrnof The Transverse Field

机译：重复淬火条件下自旋1/2横向Xy链中缺陷的产生

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摘要

We study the quenching dynamics of a one-dimensional spin-1/2 XY model in a transverse field when the transverse field h(=t/τ) is quenched repeatedly between -∞ and +∞. A single passage from h → -∞ to h → +∞ or the other way around is referred to as a half period of quenching. For an even number of half periods, the transverse field is brought back to the initial value of -∞; in the case of an odd number of half periods, the dynamics is stopped at h → + ∞. The density of defects produced due to the nonadiabatic transitions is calculated by mapping the many-particle system to an equivalent Landau-Zener problem and is generally found to vary as 1 /(τ) for large τ, however, the magnitude is found to depend on the number of half periods of quenching. For two successive half periods, the defect density is found to decrease in comparison to a single half period, suggesting the existence of a corrective mechanism in the reverse path. A similar behavior of the density of defects and the local entropy is observed for repeated quenching. The defect density decays as 1/(τ) for large τ for any number of half periods, and shows an increase in kink density for small r for an even number; the entropy shows qualitatively the same behavior for any number of half periods. The probability of nonadiabatic transitions and the local entropy saturate to 1/2 and In 2, respectively, for a large number of repeated quenching.
机译：我们研究了当横向场h（= t /τ）在-∞和+∞之间反复淬灭时，一维spin / 1/2 XY模型在横向场中的淬灭动力学。从h→-∞到h→+∞的单次通过或相反的方式称为淬灭的半周期。对于偶数个半周期，横向场将恢复为初始值-∞。在奇数个半周期的情况下，动力学在h→+∞处停止。通过将多颗粒系统映射到等效的Landau-Zener问题，可以计算出由于非绝热转变而产生的缺陷密度，对于大τ，通常发现其密度变化为（1 /）τ，但是，其大小取决于关于淬火的半周期数。对于两个连续的半周期，发现缺陷密度与单个半周期相比有所降低，这表明在反向路径中存在纠正机制。对于重复淬火，观察到缺陷密度和局部熵的相似行为。对于任何数量的半周期，对于较大的τ，缺陷密度衰减为1 /（τ），对于较小的r，对于偶数，缺陷密度会增加。熵在任何数量的半周期内定性显示相同的行为。对于大量重复淬火，非绝热跃迁和局部熵的概率分别饱和至1/2和In 2。

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