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arXiv 2204.07477cond-mat.supr-concond-mat.mes-hall
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一维超导量子涨落

Superconducting quantum fluctuations in one dimension

Andrew G. Semenov, Andrei D. Zaikin

摘要:

本文综述了准一维超导领域的一些最新进展。我们证明了超导纳米线的低温性质基本上是由量子涨落决定的。超导相的平滑(高斯)波动(也与沿着导线传播的等离子体模式相关联)可以显著影响这种纳米线中的电子态密度,并在超导纳米环中引起持续的电流噪声。进一步有趣的现象,例如,电流偏置超导纳米线中的非零电阻和电压散粒噪声是由序参量--量子相位滑移(QPS)的非高斯涨落引起的。这种现象可以解释为磁通子隧穿的有效量子“粒子”的双重库珀对和遵守复杂的全计数统计,减少到泊松一个在低频限制的作用。我们还表明,QPS效应可能是特别明显的最薄的电线和环的量子相位滑移保持不受约束,并确定一个非微扰的长度尺度$L_c$,超过该超电流得到抑制的量子波动。因此,对于$T \to 0$,这样的纳米线在超过$L_c$的尺度下应该变得绝缘,而在较短的长度尺度下,它们仍然可以表现出超导性质。我们认为,与序参量的量子涨落相关的某些非平凡特征可能对特定的电路拓扑结构敏感,并且可以在诸如,电容耦合超导纳米线系统。

英文摘要:

We review some recent developments in the field of quasi-one-dimensional superconductivity. We demonstrate that low temperature properties of superconducting nanowires are essentially determined by quantum fluctuations. Smooth (Gaussian) fluctuations of the superconducting phase (also associated with plasma modes propagating along the wire) may significantly affect the electron density of states in such nanowires and induce persistent current noise in superconducting nanorings. Further interesting phenomena such as, e.g., non-vanishing resistance and shot noise of the voltage in current-biased superconducting nanowires, are caused by non-Gaussian fluctuations of the order parameter -- quantum phase slips (QPS). Such phenomena may be interpreted in terms of tunneling of fluxons playing the role of effective quantum "particles" dual to Cooper pairs and obeying complicated full counting statistics which reduces to Poissonian one in the low frequency limit. We also demonstrate that QPS effects may be particularly pronounced in thinnest wires and rings where quantum phase slips remain unbound and determine a non-perturbative length scale $L_c$ beyond which the supercurrent gets suppressed by quantum fluctuations. Accordingly, for $T \to 0$ such nanowires should become insulating at scales exceeding $L_c$, whereas at shorter length scales they may still exhibit superconducting properties. We argue that certain non-trivial features associated with quantum fluctuations of the order parameter may be sensitive to specific circuit topology and may be observed in structures like, e.g., a system of capacitively coupled superconducting nanowires.

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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