Two-photon driven Kerr quantum oscillator with multiple spectral degeneracies

TL;DR

This paper explores how tuning the detuning parameter in two-photon driven Kerr oscillators creates spectral degeneracies that enhance quantum error suppression and enable fast, high-fidelity quantum gates.

Contribution

It introduces the role of detuning in creating spectral degeneracies in Kerr oscillators, improving error suppression and gate performance in quantum computing.

Findings

Spectral degeneracies occur at specific detuning values.

Degeneracies lead to stronger suppression of bit-flip errors.

Combining degeneracies with colored dissipation enables fast, high-fidelity gates.

Abstract

Kerr nonlinear oscillators driven by a two-photon process are promising systems to encode quantum information and to ensure a hardware-efficient scaling towards fault-tolerant quantum computation. In this paper, we show that an extra control parameter, the detuning of the two-photon drive with respect to the oscillator resonance, plays a crucial role in the properties of the defined qubit. At specific values of this detuning, we benefit from strong symmetries in the system, leading to multiple degeneracies in the spectrum of the effective confinement Hamiltonian. Overall, these degeneracies lead to a stronger suppression of bit-flip errors. We also study the combination of such Hamiltonian confinement with colored dissipation to suppress leakage outside of the bosonic code space. We show that the additional degeneracies allow us to perform fast and high-fidelity gates while preserving a strong suppression of bit-flip errors.