Fast universal quantum gates on microwave photons with all-resonance operations in circuit QED

TL;DR

This paper proposes fast, high-fidelity universal quantum gates for microwave photons in circuit QED using all-resonance operations, significantly improving speed and fidelity over previous methods without drive fields.

Contribution

It introduces resonance-based protocols for universal quantum gates on microwave resonators, achieving faster operations and higher fidelities in circuit QED systems.

Findings

C-phase gate fidelity of 99.57% within 38.1 ns

CC-phase gate fidelity of 99.25% within 73.3 ns

Operations are performed without drive fields, simplifying implementation

Abstract

Stark shift on a superconducting qubit in circuit quantum electrodynamics (QED) has been used to construct universal quantum entangling gates on superconducting resonators in previous works. It is a second-order coupling effect between the resonator and the qubit in the dispersive regime, which leads to a slow state-selective rotation on the qubit. Here, we present two proposals to construct the fast universal quantum gates on superconducting resonators in a microwave-photon quantum processor composed of multiple superconducting resonators coupled to a superconducting transmon qutrit, that is, the controlled-phase (c-phase) gate on two microwave-photon resonators and the controlled-controlled phase (cc-phase) gates on three resonators, resorting to quantum resonance operations, without any drive field. Compared with previous works, our universal quantum gates have the higher fidelities and shorter operation times in theory. The numerical simulation shows that the fidelity of our c-phase gate is 99.57% within about 38.1 ns and that of our cc-phase gate is 99.25% within about 73.3 ns.