Fractional topological insulators of Cooper pairs induced by proximity effect

TL;DR

This paper proposes a method to realize fractional topological insulators of Cooper pairs using a quantum well of topological insulator materials in contact with a superconductor, revealing new quantum states with potential applications.

Contribution

It demonstrates that a topological insulator-superconductor heterostructure can host fractional topological states with entangled Cooper pairs, a novel state not previously observed.

Findings

Realization of fractional topological insulators in quantum wells.

Excitations carry fractional charge and spin.

Potential applications in quantum computing and spintronics.

Abstract

Certain insulating materials with strong spin-orbit coupling can conduct currents along their edges or surfaces. This phenomenon arises from the non-trivial topological properties of the electronic band-structure, and is somewhat similar to the integer quantum Hall effect of electrons in strong magnetic fields. Topological insulators analogous to the fractional quantum Hall effect are also possible, but have not yet been observed in any material. Here we show that a quantum well made from a topological band insulator such as Bi2Se3 or Bi2Te3, placed in contact with a superconductor, can be used to realize a two-dimensional topological state with macroscopic many-body quantum entanglement whose excitations carry fractional amounts of electron's charge and spin. This fractional topological insulator is a "pseudogap" state of induced spinful p-wave Cooper pairs, fundamentally significant to quantum field theory and applicable to spintronic devices and quantum computing.