Resonator-mediated quantum gate between distant charge qubits

TL;DR

This paper proposes a theoretical method for mediating quantum gates between distant charge qubits using a microwave resonator, analyzing the effects of noise and estimating achievable fidelities.

Contribution

It introduces a dispersive regime approach for photon-mediated $i$SWAP and $ ooti$SWAP gates between distant charge qubits, including noise impact analysis.

Findings

Gate fidelities below 90% with current technology.

Reducing charge qubit dephasing could improve fidelities above 95%.

Theoretical demonstration of photon-mediated quantum gates in charge qubits.

Abstract

Strong charge-photon coupling allows the coherent coupling of a charge qubit, realized by a single charge carrier (either an electron or a hole) in a double quantum dot, to photons of a microwave resonator. Here, we theoretically demonstrate that, in the dispersive regime, the photons can mediate both an $i\mathrm{SWAP}$ gate as well as a $\sqrt{i\mathrm{SWAP}}$ gate between two distant charge qubits. We provide a thorough discussion of the impact of the dominant noise sources, resonator damping and charge qubit dephasing on the average gate fidelity. Assuming a state-of-the art resonator decay rate and charge qubit dephasing rate, the predicted average gate fidelities are below 90\%. However, a decrease of the charge qubit dephasing rate by one order of magnitude is conjectured to result in gate fidelities surpassing 95\%.