Quantum-Dot Parity Effects in Trivial and Topological Josephson Junctions

Abstract

An odd-occupied quantum dot in a Josephson junction can flip transmission phase, creating a π-junction. When the junction couples topological superconductors, no phase flip is expected. We investigate this and related effects in a full-shell hybrid interferometer, using gate voltage to control dot-junction parity and axial magnetic flux to control the transition from trivial to topological superconductivity. Enhanced zero-bias conductance and critical current for odd parity in the topological phase reflects hybridization of the confined spin with zero-energy modes in the leads.

Tomography of zero-energy end modes in topological superconducting wires

“…We showed that for suitable con-figurations of the junctions, the Josephson current provides the necessary information to fully reconstruct the structure of the MZMs. These results may be useful in the experimental characterization of MZMs through the behavior of the Josephson current [12].…”

“…Quantum wires with spin-orbit coupling (SOC), proximity-induced s-wave superconductivity and a magnetic field having a component perpendicular to the direction of the SOC [1,6], are one of the most prominent systems. Several experimental works investigated realizations of this platform for topological superconductivity in wires of InAs [7][8][9][10][11][12]. The existence of MZMs leads to signatures in the behavior of the Josephson current.…”

Tomography of Zero-Energy End Modes in Topological Superconducting Wires

“…Quantum wires with spin-orbit coupling (SOC), proximityinduced s-wave superconductivity and a magnetic field B having a component perpendicular to the direction of the SOC [1,6], are one of the most prominent systems. Several works investigated realizations of this platform for topological superconductivity in wires of InAs [7][8][9][10][11][12]. The existence of MZMs leads to signatures in the behavior of the Josephson current-phase relation (CPR).…”

“…This is possible within the present experimental state of the art of the hybrid superconducting-semiconducting wires we have studied [12]. Interestingly, this regime is free from the problem of the time-scales introduced by the poor equilibration of the MZMs which affect readout processes of dynamical effects [67][68][69].…”