Qubits based on merons in magnetic nanodisks

TL;DR

This paper proposes using nanoscale merons in magnetic nanodisks as qubits for quantum computing, demonstrating their stability and the theoretical feasibility of universal quantum gates based on magnetic fields or electric currents.

Contribution

It introduces a novel qubit implementation based on merons, showing their classical stabilization and the theoretical construction of universal quantum gates.

Findings

Merons with 7-spin radius can be classically stabilized in nanodisks.

Universal quantum gates can be theoretically constructed using merons.

Merons may offer long coherence times due to topological stability.

Abstract

Merons and skyrmions are classical topological solitons. However, they will become quantum mechanical objects when their sizes are of the order of nanometers. Recently, quantum computation based on nanoscale skyrmions was proposed. Here, we propose to use a nanoscale meron in a magnetic nanodisk as a qubit, where the up and down directions of the core spin are assigned to be the qubit states $|0\rangle$ and $|1\rangle$. First, we show numerically that a meron with the radius containing only $7$ spins can be stabilized in a ferromagnetic nanodisk classically. Then, we show theoretically that universal quantum computation is possible based on merons by explicitly constructing the arbitrary phase-shift gate, the Hadamard gate, and the CNOT gate. They are executed by magnetic field or electric current. It would serve as a qubit with long coherence time as a remnant of topological stability from its classical counterpart.