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arXiv 0705.1418cond-mat.supr-concond-mat.mes-hallquant-ph
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高温c轴约瑟夫森结的宏观量子隧穿理论

Theory of Macroscopic Quantum Tunneling in High-T_c c-Axis Josephson Junctions

Takehito Yokoyama, Shiro Kawabata, Takeo Kato, Yukio Tanaka

摘要:

研究了高温超导体c轴扭曲约瑟夫森结中的宏观量子隧穿,以阐明各向异性序参量对称性对宏观量子隧穿的影响.利用泛函积分和反弹方法计算了MQT速率对绕c轴扭转角$γ$的依赖关系。由于d波OPS,$γ$的开关电流分布的标准偏差和交叉温度从热激活到MQT的依赖性被发现,分别由$\cos2γ$和$\sqrt{\cos2γ}$。我们还表明,从节点准粒子激发MQT的耗散效应是可以忽略不计的小,这是符合最近的MQT实验使用Bi ${}_2$ Sr ${}_2$钙铜${}_2$ O ${}_{8 + δ}$本征结。这些结果表明,c轴扭转结中的MQT是一种有效的测试高温超导材料低温光功率谱的实验工具,并表明这种结在量子比特应用中具有很大的潜力。

英文摘要:

We study macroscopic quantum tunneling (MQT) in c-axis twist Josephson junctions made of high-T_c superconductors in order to clarify the influence of the anisotropic order parameter symmetry (OPS) on MQT. The dependence of the MQT rate on the twist angle $γ$ about the c-axis is calculated by using the functional integral and the bounce method. Due to the d-wave OPS, the $γ$ dependence of standard deviation of the switching current distribution and the crossover temperature from thermal activation to MQT are found to be given by $\cos2γ$ and $\sqrt{\cos2γ}$, respectively. We also show that a dissipative effect resulting from the nodal quasiparticle excitation on MQT is negligibly small, which is consistent with recent MQT experiments using Bi${}_2$Sr${}_2$CaCu${}_2$O${}_{8 + δ}$ intrinsic junctions. These results indicate that MQT in c-axis twist junctions becomes a useful experimental tool for testing the OPS of high-T_c materials at low temperature, and suggest high potential of such junctions for qubit applications.

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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