Fast and High-Fidelity Entangling Gate through Parametrically Modulated Longitudinal Coupling

TL;DR

This paper proposes a method for fast, high-fidelity entangling gates in quantum computing by modulating longitudinal qubit-oscillator coupling, enabling strong interactions without perturbative limitations.

Contribution

It introduces a novel approach to implement controlled-phase gates using longitudinal coupling modulation, achieving large interaction strengths and high fidelities.

Findings

Gate infidelity can be exponentially suppressed with squeezing.

The method enables short gate times and high fidelities.

Applicable to superconducting and spin qubits.

Abstract

We investigate an approach to universal quantum computation based on the modulation of longitudinal qubit-oscillator coupling. We show how to realize a controlled-phase gate by simultaneously modulating the longitudinal coupling of two qubits to a common oscillator mode. In contrast to the more familiar transversal qubit-oscillator coupling, the magnitude of the effective qubit-qubit interaction does not rely on a small perturbative parameter. As a result, this effective interaction strength can be made large, leading to short gate times and high gate fidelities. We moreover show how the gate infidelity can be exponentially suppressed with squeezing and how the entangling gate can be generalized to qubits coupled to separate oscillators. Our proposal can be realized in multiple physical platforms for quantum computing, including superconducting and spin qubits.