Solid state Stern-Gerlach spin-splitter for magnetic field sensoring, spintronics, and quantum computing

TL;DR

This paper proposes a solid state device based on topological insulators that functions as a spin-splitter, magnetic flux sensor, and quantum gate, with potential applications in spintronics and quantum computing.

Contribution

It introduces a novel solid state Stern-Gerlach spin-splitter using topological insulator edges, enabling magnetic sensing, spintronics switching, and quantum gate implementation.

Findings

Device can measure magnetic flux via Aharonov-Bohm interference.

Switchable spintronics NOT-gate demonstrated with metallic leads.

Sequence of devices can realize a single-qubit SU(2) quantum gate.

Abstract

We show that the edge of a two-dimensional topological insulator can be used to construct a solid state Stern-Gerlach spin-splitter. By threading such a Stern-Gerlach apparatus with a magnetic flux, Ahranov-Bohm like interference effects are introduced. Using ferromagnetic leads, the setup can be used to both measure magnetic flux and as a spintronics switch. With normal metallic leads a switchable spintronics NOT-gate can be implemented. Furthermore, we show that a sequence of such devices can be used to construct a single-qubit $SU(2)$-gate, one of the two gates required for a universal quantum computer. The field sensitivity, or switching field, $b$ is related to the device characteristic size $r$ through $b = \frac{\hbar}{qr^2}$, with $q$ the unit of electric charge.