Parasitic-free gate: A protected switch between idle and entangled states

TL;DR

This paper introduces a superconducting qubit gate that enables fast, error-free switching between idle and entangled states without residual interactions, using cross resonance on minimally tunable circuits.

Contribution

A novel superconducting gate design that avoids residual ZZ interactions and operates efficiently on weakly tunable circuits, enhancing quantum control.

Findings

The gate effectively switches qubit interactions without residual errors.

It operates rapidly on circuits with limited tunability.

Theoretical analysis confirms error-free operation modes.

Abstract

We propose a gate to switch superconducting qubit pairs in and out of a two-body interaction. This gate uses cross resonance driving on a tunable circuit with adjusted parameters and without accumulating residual ZZ interaction for idle and interacting qubits. It is imperative that this gate does not spread errors through the quantum register. Our detailed theoretical results show that these error-free modes do not necessarily require largely tunable circuits, such as magnetic modulation of qubits or couplers. We obtain the operational gate on weakly tuneable circuits as well and show that switching between them is remarkably fast.