Yuval Oreg

Majorana zero modes in condensed matter systems have been the subject of much interest in recent years. To form the Majoranas time-reversal symmetry must be broken. The straightforward mechanisms for doing so, e.g., the application of large magnetic Zeeman fields, turned out to have many unwanted side effects, such as forming in-gap magnetic impurity states. We will introduce a scheme in which a systematic manipulation of the phases of three superconducting pads tunes the system into a topological state. That scheme requires a tiny field that could be even less than a microtesla. We will introduce several platforms, including wires, planar 2D, and two layers of 2D systems. Our platforms rely on two key ingredients. First, the three superconductors form phase winding. Second, the system contains semiclassical trajectories with an Aharonov-Casher phase leading to different Fermi velocities for the two spin branches. Our scheme is very general, allowing us to propose additional material platforms with unequal Fermi velocities, establishing the experimental feasibility of our approach