Flux-Tunable Josephson Diode Effect in a Hybrid Four-Terminal Josephson Junction

Abstract

We investigate the direction-dependent switching current in a flux-tunable four-terminal Josephson junction defined in an InAs/Al two-dimensional heterostructure. The device exhibits the Josephson diode effect with switching currents that depend on the sign of the bias current. The superconducting diode efficiency, reaching a maximum of |η| ≈ 34%, is widely tunable�both in amplitude and sign�as a function of magnetic fluxes and gate voltages. Our observations are supported by a circuit model of three parallel Josephson junctions with nonsinusoidal current−phase relation. With respect to conventional Josephson interferometers, phasetunable multiterminal Josephson junctions enable large diode efficiencies in structurally symmetric devices, where local magnetic fluxes generated on the chip break both time-reversal and spatial symmetries. Our work presents an approach for developing Josephson diodes with wide-range tunability that do not rely on exotic materials.

Josephson Diode Effect in Parallel-Coupled Double Quantum Dots Connected to Majorana Nanowires

“…In such systems, the Josephson currents are contributed from higher harmonics other than the usual 2π-periodic ones with a magnetic flux penetrating through the SQUID loop [6,8,14]. It has recently been demonstrated in two-dimensional electron and many three-and four-terminal setups in which the diode efficiencies at equilibrium can reach up to about 30% [20,21].…”

“…Until now, there are two limitations in previous work on Josephson current through MNWs-QD-MNWs systems: one is that only the current's magnitude and period were studied, whereas less attention has been paid on the control of its direction [32][33][34][35][36]; the other is that only single QD was proposed to be inserted between two MNWs, and the interesting quantum interference effect was left untouched [14,16,20,21,38,[40][41][42][43]46,47]. In view of these, we propose a structure composed of parallel double QDs (DQDs) sandwiched between the left and right MNWs to achieve the JDE based on quantum interference effect arising from the two transport paths through the DQDs, as well as the magnetic flux penetrating through the loop, which is shown in Figure 1.…”