Operation of a high-frequency, phase-slip qubit

TL;DR

This paper demonstrates a superconducting qubit based on a titanium nitride phase-slip junction, showing high coherence, operation at elevated temperatures, and potential for new protected qubit types in quantum computing.

Contribution

It introduces a phase-slip junction qubit made with titanium nitride, enabling high-temperature operation and expanding the toolkit for superconducting quantum information processing.

Findings

Qubit lifetime exceeds 60 microseconds

Operation at temperatures above 300 millikelvin

Qubit frequency around 17 GHz controlled by inductance

Abstract

Aluminum-based Josephson junctions are currently the main sources of nonlinearity for control and manipulation of superconducting qubits. A phase-slip junction, the dual of a Josephson junction, provides an alternative source of nonlinearity that promises new types of protected qubits and the possibility of high-temperature and high-frequency operation through the use of superconductors with larger energy gaps. Phase-slip junctions have been challenging, however, to incorporate into superconducting qubits because of difficulty controlling junction parameters. Here we demonstrate the operation of a superconducting qubit based on a phase slip junction made using titanium nitride. We operate the qubit at zero flux where the qubit frequency (~17 GHz) is mainly determined by the inductance of the qubit. We perform readout and coherent control of the superconducting qubit, and measure qubit lifetimes >60 $\mu$s. Finally, we demonstrate operation of the qubit at temperatures exceeding 300 mK. Our results add the phase-slip junction as a tool for superconducting quantum information processing and opens avenues for new classes of superconducting qubits.