Chiral p -wave superconductivity in a twisted array of proximitized quantum wires

Abstract

A superconductor with px + ipy order has long fascinated the physics community because vortex defects in such a system host Majorana zero modes. Here we propose a simple construction of a chiral superconductor using proximitized quantum wires and twist angle engineering as basic ingredients. We show that a weakly coupled parallel array of such wires forms a gapless p-wave superconductor. Two such arrays, stacked on top of one another with a twist angle close to 90 • , spontaneously break time reversal symmetry and form a robust, fully gapped px + ipy superconductor. We map out topological phases of the proposed system, demonstrate existence of Majorana zero modes in vortices, and discuss prospects for experimental realization.

High-temperature Majorana zero modes

“…in Ref. [32] the corresponding wavefunction amplitudes are localized at the vortex core and the edge, respectively (insets Fig. 4).…”

Giant Kerr effect of a p x + ip y superconductor engineered by semiconductor nanowires

“…As explained in the introduction section in detail, we are going to study the Hall response of a geometry which produces a chiral superconductor p x + ip y . Following [29], we consider two stacked array layers twisted with respect to each other by 90°. The layer 1 (2) consists of wires which are stacked next to each other, parallel to the x (y) axis.…”

“…Another prominent example of the hybrid systems which is recently proposed includes two layers which are stacked on top each other with a relative twist angle of 90° [29]. Each layer is composed of weakly coupled parallel nanowires which coated on one side with a thin layer of conventional superconductor parallel nanowires and produces p i -wave superconductor (direction 'i' is parallel to wire).…”

Non-Abelian topological superconductivity in maximally twisted double-layer spin-triplet valley-singlet superconductors

“…Despite its promise for realizing high-T c TSC, a chiral d ± id 0 superconductor cannot host truly non-Abelian excitations due to its spin-singlet pairing nature, which is always associated with an even number of MZMs that combine to form usual Abelian fermions. Generalizing the scheme to spin-triplet superconductors with nodal p-wave or fwave order parameters one can create chiral SC phases with an odd number of MZMs in principle 33 , while once again facing the scarcity of nodal p-wave and f-wave superconductors in nature.…”