Universal quantum computation based on nanoscale skyrmion helicity qubits in frustrated magnets

TL;DR

This paper proposes a method for universal quantum computation using nanoscale skyrmion helicity qubits in frustrated magnets, enabling quantum gates control via electric fields and spin currents without external magnetic fields.

Contribution

It introduces a novel qubit based on skyrmion helicity degeneracy and demonstrates how to implement universal quantum gates in multilayered magnetic systems.

Findings

Constructed a skyrmion-based qubit with two helicity states.

Demonstrated implementation of C4/4, Hadamard, and CNOT gates.

Achieved quantum computation control without external magnetic fields.

Abstract

Skyrmions in frustrated magnets have the helicity degree of freedom, where two different configurations of Bloch-type skyrmions are energetically favored by the magnetic dipole-dipole interaction and characterized by opposite helicities. A skyrmion must become a quantum-mechanical object when its radius is of the order of nanometer. We construct a qubit based on the two-fold degeneracy of the Bloch-type nanoscale skyrmions in frustrated magnets. It is shown that the universal quantum computation is possible based on nanoscale skyrmions in a multilayered system. We explicitly show how to construct the $\pi /4$ phase-shift gate, the Hadamard gate, and the CNOT gate. The one-qubit quantum gates are materialized by temporally controlling the electric field and the spin current. The two-qubit gate is materialized with the use of the Ising-type exchange coupling by controlling the distance between the skyrmion centers in two adjacent layers. The merit of the present mechanism is that an external magnetic field is not necessary. Our results may open a possible way toward universal quantum computations based on nanoscale topological spin textures.