Suppressed crosstalk between two-junction superconducting qubits with mode-selective exchange coupling

TL;DR

This paper demonstrates a superconducting qubit architecture that uses mode-selective exchange coupling to suppress crosstalk between two-junction qubits, enabling independent control and microwave two-qubit gates.

Contribution

It introduces a mode-selective coupling method in two-junction superconducting qubits to reduce crosstalk and improve quantum gate control.

Findings

Crosstalk between qubits is significantly suppressed.

Selective coupling enables all-microwave two-qubit gates.

Two modes with distinct frequencies and symmetries are utilized.

Abstract

Fixed-frequency qubits can suffer from always-on interactions that inhibit independent control. Here, we address this issue by experimentally demonstrating a superconducting architecture using qubits that comprise of two capacitively-shunted Josephson junctions connected in series. Historically known as tunable coupling qubits (TCQs), such two-junction qubits support two modes with distinct frequencies and spatial symmetries. By selectively coupling only one type of mode and using the other as our computational basis, we greatly suppress crosstalk between the data modes while permitting all-microwave two-qubit gates.