Cavity-mediated cross-cross-resonance gate

TL;DR

This paper introduces a cavity-mediated cross-cross-resonance gate for superconducting qubits, enabling controlled-phase operations and simultaneous multi-qubit gates via cavity coupling, with error mitigation strategies.

Contribution

It proposes a novel cavity-mediated gate mechanism for superconducting qubits, including error cancellation schemes and multi-qubit gate capabilities.

Findings

The gate operates via cavity-induced phase space trajectories.

Error cancellation schemes effectively reduce dispersive coupling errors.

The approach enables simultaneous gates between multiple qubit pairs.

Abstract

We propose a cavity-mediated gate between two transmon qubits or other nonlinear superconducting elements. The gate is realized by driving both qubits at a frequency that is near-resonant with the frequency of the cavity. Since both qubits are subject to a cross-resonant drive, we call this gate a cross-cross-resonance gate. In close analogy with gates between trapped-ion qubits, in phase space, the state of the cavity makes a circle whose area depends on the state of the two qubits, realizing a controlled-phase gate. We propose two schemes for canceling the dominant error, which is the dispersive coupling. We also show that this cross-cross-resonance gate allows one to realize simultaneous gates between multiple pairs of qubits coupled via the same metamaterial composed of an array of coupled cavities or other linear mediators.