Department of Physics, The University of Texas at Dallas, Richardson, Texas 75080-3021, USA.
Department of Physics and Astronomy, Washington State University, Pullman, Washington 99164, USA.
Phys Rev Lett. 2018 Mar 23;120(12):120401. doi: 10.1103/PhysRevLett.120.120401.
The Josephson effect is a prominent phenomenon of quantum supercurrents that has been widely studied in superconductors and superfluids. Typical Josephson junctions consist of two real-space superconductors (superfluids) coupled through a weak tunneling barrier. Here we propose a momentum-space Josephson junction in a spin-orbit coupled Bose-Einstein condensate, where states with two different momenta are coupled through Raman-assisted tunneling. We show that Josephson currents can be induced not only by applying the equivalent of "voltages," but also by tuning tunneling phases. Such tunneling-phase-driven Josephson junctions in momentum space are characterized through both full mean field analysis and a concise two-level model, demonstrating the important role of interactions between atoms. Our scheme provides a platform for experimentally realizing momentum-space Josephson junctions and exploring their applications in quantum-mechanical circuits.
约瑟夫森效应是量子超导中的一个突出现象，在超导和超流中得到了广泛的研究。典型的约瑟夫森结由两个实空间超导体（超流）通过弱隧道势垒耦合而成。在这里，我们在自旋轨道耦合玻色-爱因斯坦凝聚体中提出了一种动量空间约瑟夫森结，其中具有两个不同动量的状态通过拉曼辅助隧道耦合。我们表明，不仅通过施加等效的“电压”，而且通过调整隧道相位也可以诱导约瑟夫森电流。这种动量空间中的隧道相位驱动的约瑟夫森结通过全平均场分析和简洁的两能级模型进行了特征描述，展示了原子之间相互作用的重要作用。我们的方案为实验实现动量空间约瑟夫森结并探索其在量子力学电路中的应用提供了一个平台。
