Zero-Energy Modes from Coalescing Andreev States in a Two-Dimensional Semiconductor-Superconductor Hybrid Platform

Abstract

We investigate zero-bias conductance peaks that arise from coalescing subgap Andreev states, consistent with emerging Majorana zero modes, in hybrid semiconductor-superconductor wires defined in a two-dimensional InAs/Al heterostructure using top-down lithography and gating. The measurements indicate a hard superconducting gap, ballistic tunneling contact, and in-plane critical fields up to 3 T. Top-down lithography allows complex geometries, branched structures, and straightforward scaling to multicomponent devices compared to structures made from assembled nanowires.

Distinguishing Majorana zero modes from impurity states through time-resolved transport

“…They are thus considered to be promising candidates for technological advances in topological quantum computing [6][7][8] since their non-abelian statistics allow performing quantum computation protected from environmental perturbations [9]. Even though various experimental signatures of MZM have been reported [10][11][12][13][14][15][16][17], a clear and unambiguous detection and the consequent control of these states has proven difficult so far. For example, other types of bound states [18], surface states or interfacial impurity states (IS) also give rise to in-gap states that contribute to transport or scanning tunneling spectroscopy signals.…”

Majorana qubits in a topological insulator nanoribbon architecture

“…Nonetheless, the chemical potential window allowing for robust MBSs is arguably bigger for the TI nanoribbon case. Moreover, the implementation of Majorana box qubits in a semiconductor nanowire setting has encountered difficulties due to the need for separate reference links [55]. Using our TI nanoribbon setup (and similarly for 2DEG imple-A B Figure 5.…”

Josephson effect in multiterminal topological junctions

“…The possibility to induce topological superconductivity in semiconducting nanowires with strong spin-orbit coupling (e.g., InAs or InSb) by proximity coupling to a conventional superconductor has paved the way to exciting novel developments [1][2][3][4][5][6][7][8][9][10][11][12][13]. In particular, presently available devices with a hard superconducting gap [8][9][10][11] and disorder levels close to the ballistic limit [12,13] exhibit characteristic transport signatures as expected for Majorana bound states (MBSs).…”

“…In particular, presently available devices with a hard superconducting gap [8][9][10][11] and disorder levels close to the ballistic limit [12,13] exhibit characteristic transport signatures as expected for Majorana bound states (MBSs). The latter are robust states localized at the wire ends within the topological phase.…”

“…[14][15][16][17][18], and many of our results below apply to those implementations as well. It stands to reason that the currently developed technologies will give access to quantum transport studies in a wide variety of hybrid structures involving topological superconductor (TS) wires, including multiterminal geometries [12,13,19]. Such devices may also be of interest for topological quantum information processing applications [2][3][4].…”