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arXiv 2307.04835cond-mat.supr-concond-mat.mes-hallcond-mat.stat-mech
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关于电阻分流约瑟夫森结中Schmid转变的本质

On the nature of the Schmid transition in a resistively shunted Josephson junction

Romain Daviet, Nicolas Dupuis

AI总结:

本研究借助非微扰泛函重整化群方法探究电阻分流约瑟夫森结的Schmid转变,发现其由不动点线控制且临界指数与电导连续变化,修正了传统相图认知并与模拟结果做了对比。

摘要:

我们在边界sine-Gordon模型的框架下研究了电阻分流约瑟夫森结(RSJJ)的相图。利用非微扰泛函重整化群(FRG)方法,我们发现该转变并非由单个不动点控制,而是由一条不动点线控制,并计算了连续变化的临界指数$ν$。我们认为电导也会沿转变线连续变化。与RSJJ的传统相图——即当分流电阻$R$大于$R_q=h/(2e)^2$时为绝缘基态,当$R<R_q$时为超导基态——不同,FRG预测$(α,E_J/E_C)$平面内的转变线在$α=R_q/R<1$的区域发生弯曲,但我们无法排除在$α=1$处存在竖直线的可能性($E_J$和$E_C$分别表示结的约瑟夫森能和充电能)。我们将相图和转变本质的相关结果与蒙特卡洛模拟及数值重整化群结果进行了比较。

英文摘要:

We study the phase diagram of a resistively shunted Josephson junction (RSJJ) in the framework of the boundary sine-Gordon model. Using the non-perturbative functional renormalization group (FRG) we find that the transition is not controlled by a single fixed point but by a line of fixed points, and compute the continuously varying critical exponent $ν$. We argue that the conductance also varies continuously along the transition line. In contrast to the traditional phase diagram of the RSJJ -- an insulating ground state when the shunt resistance $R$ is larger than $R_q=h/(2e)^2$ and a superconducting one when $R<R_q$ -- the FRG predicts the transition line in the plane $(α,E_J/E_C)$ to bend in the region $α=R_q/R<1$ but we cannot discard the possibility of a vertical line at $α=1$ ($E_J$ and $E_C$ denote the Josephson and charging energies of the junction, respectively). Our results regarding the phase diagram and the nature of the transition are compared with Monte Carlo simulations and numerical renormalization group results.

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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