Full electrostatic control of quantum interference in an extended trenched Josephson junction

Abstract

Hybrid semiconductor/superconductor devices constitute an important platform for a wide range of applications, from quantum computing to topological-state-based architectures. Here, we demonstrate full modulation of the interference pattern in a superconducting interference device with two parallel islands of ballistic InAs quantum wells separated by a trench, by acting independently on two side-gates. This so far unexplored geometry enables us to tune the device with high precision from a SQUID-like to a Fraunhofer-like behavior simply by electrostatic gating, without the need for an additional in-plane magnetic field. These measurements are successfully analyzed within a theoretical model of an extended tunnel Josephson junction, taking into account the focusing factor of the setup. The impact of these results on the design of novel devices is discussed.

Investigation of InAs–based devices for topological applications

“…Second, we report on the realization of hybrid Josephson junctions formed by an InAs quantum well between two Nb contacts. 29,30 Here, we demonstrate supercurrent flow, whose amplitude can be tuned acting on two side gates, with Nb critical fields of the order of 3T. It has been shown that in these structures, at these magnetic fields, well-developed quantum Hall plateaus appear, 29 allowing for the study of the coexistence of superconducting correlations and quantum Hall regime, [31][32][33] two important ingredients for the emergence of topological quasiparticles in 2DEG-based hybrid structures.…”

Assessing Bound States in a One-Dimensional Topological Superconductor: Majorana versus Tamm

“…Recently, the possibility to employ quantum point contacts [23] instead of magnetic barriers has been considered, providing a promising alternative for topological insulator-based Majorana platforms [24,25]. Several other platforms have been proposed, ranging from ferromagnetic atomic chains with superconducting pairing [26], planar Josephson junctions in 2D semiconductors [27][28][29], and the more popular setup based on spin-orbit-coupled quantum wire with proximity superconductivity and applied magnetic fields [30,31].…”

Current correlations of Cooper-pair tunneling into a quantum Hall system

“…In the recent past, it has become possible to investigate such transport problems not only between identical ballistic chiral QH states but also between distinct systems, such as QH edge states and superconductors, both theoretically [61][62][63][64][65][66][67][68][69][70] and experimentally [19,20,22,[71][72][73][74]. This line of research is particularly relevant for the creation of parafermion bound states, non-Abelian quasiparticles with potential application in topological quantum computation [75][76][77][78][79][80][81][82][83][84].…”