Effective model for a short Josephson junction with a phase discontinuity
Effective model for a short Josephson junction with a phase discontinuity
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DOI：
10.1103/physrevb.93.134514
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发表时间：
2015-08
影响因子：
3.7
通讯作者：
E. Goldobin;S. Mironov;A. Buzdin;R. Mints;D. Koelle;R. Kleiner
中科院分区：
文献类型：
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作者：
E. Goldobin;S. Mironov;A. Buzdin;R. Mints;D. Koelle;R. Kleiner
我们考虑一个短的约瑟夫森结与相位不连续$\kappa$创建，例如，通过一对微小的电流注入器，在沿着结的长度的某个点沿着。我们推导出整个系统的有效电流-相位关系（CPR），即，将其缩减为有效的点状连接。从有效的CPR，我们得到的系统的基态，并预测其临界电流的依赖$\kappa$。我们表明，在大范围的$\kappa$值的有效结的行为作为一个$\varphi_0 $约瑟夫森结，即，在每个$2\pi$间隔内具有唯一的基态相位$\varphi_0$。对于$\kappa\approx\pi$和靠近结中间的$x_0$，可以得到$\varphi_0\pm\varphi$结，即，在每个$2\pi$间隔内具有退化基态相位$\varphi_0\pm\varphi$约瑟夫森结。此外，鉴于可能的逃逸实验，特别是在量子域中，我们调查的缩放的能量势垒和本征频率接近的临界电流和预测的行为的逃逸直方图宽度$\sigma（\kappa）$在制度的宏观量子隧穿。
We consider a short Josephson junction with a phase discontinuity $\kappa$ created, e.g., by a pair of tiny current injectors, at some point $x_0$ along the length of the junction. We derive the effective current-phase relation (CPR) for the system as a whole, i.e., reduce it to an effective point-like junction. From the effective CPR we obtain the ground state of the system and predict the dependence of its critical current on $\kappa$. We show that in a large range of $\kappa$ values the effective junction behaves as a $\varphi_0$ Josephson junction, i.e., has a unique ground state phase $\varphi_0$ within each $2\pi$ interval. For $\kappa\approx\pi$ and $x_0$ near the middle of the junction one obtains a $\varphi_0\pm\varphi$ junction, i.e., the Josephson junction with degenerate ground state phase $\varphi_0\pm\varphi$ within each $2\pi$ interval. Further, in view of possible escape experiments especially in the quantum domain, we investigate the scaling of the energy barrier and eigenfrequency close to the critical currents and predict the behavior of the escape histogram width $\sigma(\kappa)$ in the regime of the macroscopic quantum tunneling.