Topological superconductivity in a phase-controlled Josephson junction

Abstract

Topological superconductors can support localized Majorana states at their boundaries. These quasi-particle excitations have non-Abelian statistics that can be used to encode and manipulate quantum information in a topologically protected manner. While signatures of Majorana bound states have been observed in one-dimensional systems, there is an ongoing effort to find alternative platforms that do not require fine-tuning of parameters and can be easily scalable to large numbers of states. Here we present a novel experimental approach towards a two-dimensional architecture. Using a Josephson junction made of HgTe quantum well coupled to thin-film aluminum, we are able to tune between a trivial and a topological superconducting state by controlling the phase difference φ across the junction and applying an in-plane magnetic field. We determine the topological state of the induced superconductor *

Signature of a pair of Majorana zero modes in superconducting gold surface states

“…Up to now, various proposals have been made to engineer TSCs by combining conventional materials, [3][4][5][6][7][8][9] and great progress has been made towards revealing the signatures of MZMs. [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27] However, direct experimental tunneling data showing that MZMs appear simultaneously in pairs is still missing, [28][29][30] even though indirect evidence of the spatial dependence of the overlap between two MZM's have been reported. 17 Our paper provides the tunneling data that directly confirm the key property of MZM, i.e.…”

“…While progress towards using planar semiconductor heterostructures has recently been reported, 25,27 our metal-based platform holds a number of intrinsic advantages. First there is a wealth of experience in epitaxial growth of noble metals on a variety of superconductors, [31][32][33] as well as epitaxial growth of ferromagnetic insulators on top.…”

Phase Control of Majorana Bound States in a Topological X Junction

“…A push to seek alternative platforms for topological superconductivity led to the demonstration of robust proximityinduced superconductivity in a two-dimensional electron gas (2DEG) [18][19][20] which offers important opportunities to realize and control MBS [21][22][23][24][25][26][27]. Recent experiments in planar Josephson junctions (JJs) [28][29][30] reveal that topological superconductivity exists over a large parameter space without requiring fine tuning, while demonstrating the key role of superconducting phase to control the topological transition.…”

Revealing the nonlocal coherent nature of Majorana devices from dissipative teleportation

“…non-Abelian braiding statistics [3][4][5][6], and has potential applications in quantum information processing and topological quantum computation [6,7]. Many proposals for realizing MZMs in topological superconductors (SCs) have been put forward [8][9][10][11][12][13][14][15], and lead to recent experimental progress in the realization and detection of MZM in both one-dimensional [16][17][18][19][20][21][22][23][24][25][26][27] and two-dimensional platforms [28][29][30][31][32][33][34]. The quantized Majorana conductance at 2e 2 /h, observed in nanowire devices [27], closes one chapter in tunneling spectroscopy based on the simplest device set-ups.…”