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arXiv 2102.03134cond-mat.stat-mech
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噪声存在下的受驱动量子自旋链:Anti-Kibble-Zurek行为

Driven quantum spin chain in the presence of noise: Anti-Kibble-Zurek behavior

Manvendra Singh, Suhas Gangadharaiah

摘要:

我们研究了在含时快高斯噪声中,由于多体哈密顿量的线性驱动而产生的量子XY自旋链中的缺陷产生。这项工作的主要目标是量化分析噪声对缺陷密度生产的影响。在没有噪声的情况下,众所周知,在慢扫描状态下,缺陷密度遵循关于扫描速度的Kibble-Zurek(KZ)标度行为。我们认为时间相关的快速高斯噪声的自旋耦合项[ $γ_0=(J_1-J_2)/(J_1+J_2)$ ]的各向异性,并通过分析计算表明,缺陷密度表现出反Kibble-Zurek(AKZ)标度行为在缓慢的扫描制度。在大链长和长时间的限制下,我们计算了最终退相干态的熵和磁化强度密度,并表明它们的标度行为与慢扫描区的AKZ图像一致。我们还通过计算Toeplitz行列式数值计算了有限分离的亚晶格自旋自旋双折射子,发现在没有噪声的情况下,结果与KZ图一致,而在存在噪声和慢扫描速度的情况下,双折射子表现出AKZ行为。此外,通过考虑大的$n$分离渐近线的Toeplitz行列式,我们进一步量化的效果上的自旋-自旋纠缠在最终的decoeconomic状态。我们表明,而根据AKZ行为的子晶格相关器的相关长度的尺度,我们得到不同的磁化强度放大器的缩放。

英文摘要:

We study defect generation in a quantum XY-spin chain arising due to the linear drive of the many-body Hamiltonian in the presence of a time-dependent fast Gaussian noise. The main objective of this work is to quantify analytically the effects of noise on the defect density production. In the absence of noise, it is well known that in the slow sweep regime, the defect density follows the Kibble-Zurek (KZ) scaling behavior with respect to the sweep speed. We consider time-dependent fast Gaussian noise in the anisotropy of the spin-coupling term [$γ_0=(J_1-J_2)/(J_1+J_2)$] and show via analytical calculations that the defect density exhibits anti-Kibble-Zurek (AKZ) scaling behavior in the slow sweep regime. In the limit of large chain length and long time, we calculate the entropy and magnetization density of the final decohered state and show that their scaling behavior is consistent with the AKZ picture in the slow sweep regime. We have also numerically calculated the sub-lattice spin correlators for finite separation by evaluating the Toeplitz determinants and find results consistent with the KZ picture in the absence of noise, while in the presence of noise and slow sweep speeds the correlators exhibit the AKZ behavior. Furthermore, by considering the large $n$-separation asymptotes of the Toeplitz determinants, we further quantify the effect of the noise on the spin-spin correlators in the final decohered state. We show that while the correlation length of the sub-lattice correlator scales according to the AKZ behavior, we obtain different scaling for the magnetization correlators.

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