Three-mode tunable coupler for superconducting two-qubit gates

TL;DR

This paper introduces a three-mode tunable coupler for superconducting qubits, enabling high-fidelity, fast two-qubit gates with potential for scalable quantum processors.

Contribution

It presents a novel three-mode tunable coupler design that achieves high-fidelity CZ gates with fast operation times in superconducting qubits.

Findings

Achieved a 98% fidelity for a 60 ns CZ gate.

Demonstrated the tunable coupler's effectiveness in controlling qubit interactions.

Simulations suggest fidelity can exceed 99.97% with optimization.

Abstract

Building a scalable universal high-performance quantum processor is a formidable challenge. In particular, the problem of realizing fast high-perfomance two-qubit gates of high-fidelity remains needful. Here we propose a building block for a scalable quantum processor consisting of two transmons and a tunable three-mode coupler allowing for a ZZ interaction control. We experimentally demonstrate the native CZ gate with the pulse duration of 60 ns achieving the two-qubit gate fidelity above 98%, limited mostly by qubit coherence time. Numerical simulations show that by optimizing the gate duration the fidelity can be pushed over 99.97%.