Fast tunable coupling scheme of Kerr parametric oscillators based on shortcuts to adiabaticity

TL;DR

This paper presents a fast, tunable coupling scheme for Kerr parametric oscillators using shortcuts to adiabaticity, enabling rapid, high-fidelity quantum gate operations without complex control hardware.

Contribution

It introduces a simple, high-speed coupling method for KPOs based on phase-space rotation, avoiding additional drives or couplers, and improves quantum gate fidelity.

Findings

Achieves rapid switching of KPO coupling via phase control.

Demonstrates high-fidelity two-qubit gate implementation.

Mitigates nonadiabatic errors with the proposed scheme.

Abstract

Kerr parametric oscillators (KPOs), which can be implemented with superconducting parametrons possessing large Kerr nonlinearity, have been attracting much attention in terms of their applications to quantum annealing, universal quantum computation and studies of quantum many-body systems. It is of practical importance for these studies to realize fast and accurate tunable coupling between KPOs in a simple manner. We develop a simple scheme of fast tunable coupling of KPOs with high tunability in speed and amplitude using the fast transitionless rotation of a KPO in the phase space based on the shortcuts to adiabaticity. Our scheme enables rapid switching of the effective coupling between KPOs, and can be implemented with always-on linear coupling between KPOs, by controlling the phase of the pump field and the resonance frequency of the KPO without controlling the amplitude of the pump field nor using additional drive fields and couplers. We apply the coupling scheme to a two-qubit gate, and show that our scheme realizes high gate fidelity compared to a purely adiabatic one, by mitigating undesired nonadiabatic transitions.