Optimized controlled Z gates for two superconducting qubits coupled through a resonator

TL;DR

This paper develops optimized control pulses for fast, high-fidelity controlled Z gates in superconducting qubits coupled via a resonator, addressing decoherence and systematic errors.

Contribution

It introduces a numerical method to design faster controlled Z gates with adjustable fidelity, tailored for superconducting qubits coupled through a resonator.

Findings

Gates can be sped up by a factor of two.

Any target fidelity can be achieved with the optimized pulses.

Strategies are provided to mitigate systematic errors in experimental implementations.

Abstract

Superconducting qubits are a promising candidate for building a quantum computer. A continued challenge for fast yet accurate gates to minimize the effects of decoherence. Here we apply numerical methods to design fast entangling gates, specifically the controlled Z, in an architecture where two qubits are coupled via a resonator. We find that the gates can be sped up by a factor of two and reach any target fidelity. We also discuss how systematic errors arising from experimental conditions affect the pulses and how to remedy them, providing a strategy for the experimental implementation of our results. We discuss the shape of the pulses, their spectrum and symmetry.