Magnon-mediated quantum gates for superconducting qubits

TL;DR

This paper introduces a hybrid quantum system where magnons mediate interactions between superconducting qubits, enabling high-fidelity two-qubit gates and offering a new platform for quantum computing architectures.

Contribution

It proposes a novel magnon-mediated coupling scheme for superconducting qubits, demonstrating tunable interactions and high-fidelity gate operations under realistic conditions.

Findings

iSWAP and CZ gates with >99% fidelity

iCNOT gate with >88% fidelity

Tunable qubit-qubit interactions (XX+YY, ZZ, ZX)

Abstract

We propose a hybrid quantum system consisting of a magnetic particle inductively coupled to two superconducting transmon qubits, where qubit-qubit interactions are mediated via magnons. We show that the system can be tuned into three different regimes of effective qubit-qubit interactions, namely a transverse ($XX + YY$), a longitudinal ($ZZ$) and a non-trivial $ZX$ interaction. In addition, we show that an enhanced coupling can be achieved by employing an ellipsoidal magnet, carrying anisotropic magnetic fluctuations. We propose a scheme for realizing two-qubit gates, and simulate their performance under realistic experimental conditions. We find that iSWAP and CZ gates can be performed in this setup with an average fidelity $\gtrsim 99 \% $ , while an iCNOT gate can be applied with an average fidelity $\gtrsim 88 \%$. Our proposed hybrid circuit architecture offers an alternative platform for realizing two-qubit gates between superconducting qubits and could be employed for constructing qubit networks using magnons as mediators.