Ultrafast Quantum Gates in Circuit QED

TL;DR

This paper proposes a method for ultrafast two-qubit gates in circuit QED that operate in the ultrastrong coupling regimes, achieving subnanosecond operation with high fidelity, advancing quantum computing capabilities.

Contribution

It introduces a novel qubit architecture and a four-step displacement protocol enabling ultrafast gates in USC and DSC regimes with high fidelity.

Findings

Gates can be performed at subnanosecond timescales

Fidelity remains above 99%

Applicable to state-of-the-art circuit QED systems

Abstract

We present a method of implementing ultrafast two-qubit gates valid for the ultrastrong coupling (USC) and deep strong coupling (DSC) regimes of light-matter interaction, considering state-of-the-art circuit quantum electrodynamics (QED) technology. Our proposal includes a suitable qubit architecture and is based on a four-step sequential displacement of an intracavity mode, operating at a time proportional to the inverse of the resonator frequency. Through ab initio calculations, we show that these quantum gates can be performed at subnanosecond time scales, while keeping the fidelity above 99%.