A charge-current-induced shift in the spin-locked Fermi surface leads to a non-equilibrium spin density at a Rashba interface, commonly known as the Rashba–Edelstein effect. Since this is an intrinsically interfacial property, direct detection of the spin moment is difficult. Here we demonstrate that a planar Josephson Junction, realized by placing two closely spaced superconducting electrodes over a Rashba interface, allows for a direct detection of the spin moment as an additional phase in the junction. Asymmetric Fraunhofer patterns obtained for Nb-(Pt/Cu)-Nb nano-junctions, due to the locking of Rashba–Edelstein spin moment to the flux quantum in the junction, provide clear signatures of this effect. This simple experiment offers a fresh perspective on direct detection of spin polarization induced by various spin-orbit effects. In addition, this platform also offers a magnetic-field-controlled phase biasing mechanism in conjunction with the Rashba–Edelstein spin-orbit effect for superconducting quantum circuits.

自旋锁定费米表面中的电荷电流引起的位移导致 Rashba 界面处的非平衡自旋密度，通常称为 Rashba-Edelstein 效应。由于这是本质上的界面特性，因此很难直接检测自旋矩。在这里，我们演示了通过在 Rashba 界面上放置两个紧密间隔的超导电极实现的平面约瑟夫森结，可以直接检测自旋矩作为结中的附加相。由于 Rashba-Edelstein 自旋矩与结中通量量子的锁定，Nb-(Pt/Cu)-Nb 纳米结获得的不对称夫琅和费图案提供了这种效应的清晰特征。这个简单的实验为直接检测各种自旋轨道效应引起的自旋极化提供了新的视角。此外，该平台还为超导量子电路提供了磁场控制的相位偏置机制，与 Rashba-Edelstein 自旋轨道效应相结合。