论文标题
四重奏线上的四端超导装置的反转：I。二维金属和四重奏束分配器
Inversion in a four-terminal superconducting device on the quartet line: I. Two-dimensional metal and the quartet beam splitter
论文作者
论文摘要
与最新的哈佛大学基于石墨烯基的实验有关的四端Josephson连接，该连接包含扎根的循环，我们考虑在四重奏线上的相反电压下偏置，并在隧道振幅中建立最低阶的扰动理论，这是在二维（2D）金属和四个超降压的导线之间在犯规限制中。另外，我们提出了一般的非扰动和非绝热结果。四重奏线$ i_c（φ/φ_0）$上的临界电流取决于减少的磁通$φ/φ_0$，通过三端四重奏（3TQ）和非标准四端拆分四重奏（4TSQ）之间的干扰。 4TSQ是由在2D量子唤醒上交换两个准颗粒“冲浪”的两个列粒连接引起的，并且该机制已经以平衡状态运行。隧道振幅中的扰动理论表明，如果触点具有线性尺寸，则3TQ是$π$缩短的，但是4TSQ是$ 0 $缩短的，与弹性平均自由路径相比，这是较大的。我们建立了四重奏临界电流振荡$ i_c（φ/φ_0）$的门电压依赖性。有人认为，“观察$ i_c（0）\ ne i_c（1/2）$“暗示”四端4TSQ的证据“对于四重奏线上的有限偏见电压和任意界面透明透明度上的有限偏置电压。该语句依赖于物理动机的近似值，导致四重奏临界电流频率关系的Ambegaokar-Baratoff型公式。结论是，上面提到的最近的实验找到了四端4TSQ的证据。
In connection with the recent Harvard group experiment on graphene-based four-terminal Josephson junctions containing a grounded loop, we consider biasing at opposite voltages on the quartet line and establish lowest-order perturbation theory in the tunnel amplitudes between a two-dimensional (2D) metal and four superconducting leads in the dirty limit. We present in addition general nonperturbative and nonadiabatic results. The critical current on the quartet line $I_c(Φ/Φ_0)$ depends on the reduced flux $Φ/Φ_0$ via interference between the three-terminal quartets (3TQ) and the nonstandard four-terminal split quartets (4TSQ). The 4TSQ result from synchronizing two Josephson junctions by exchange of two quasiparticles "surfing" on the 2D quantum wake, and this mechanism is already operational at equilibrium. Perturbation theory in the tunnel amplitudes shows that the 3TQ are $π$-shifted but the 4TSQ are $0$-shifted if the contacts have linear dimension which is large compared to the elastic mean free path. We establish the gate voltage dependence of the quartet critical current oscillations $I_c(Φ/Φ_0)$. It is argued that "Observation of $I_c(0)\ne I_c(1/2)$" implies "Evidence for the four-terminal 4TSQ" for finite bias voltage on the quartet line and arbitrary interface transparencies. This statement relies on physically-motivated approximations leading to the Ambegaokar-Baratoff-type formula for the quartet critical current-flux relation. It is concluded that the recent experiment mentioned above finds evidence for the four-terminal 4TSQ.
