Superconducting cavity qubit with tens of milliseconds single-photon coherence time

TL;DR

This paper reports a superconducting cavity qubit with a record 34 ms coherence time, significantly advancing quantum memory duration and enabling storage of large Schrödinger cat states for quantum error correction.

Contribution

Introduction of a superconducting cavity qubit with over ten times longer coherence time than previous devices, enhancing quantum memory capabilities.

Findings

Coherence time of 34 ms achieved

Stored Schrödinger cat state with 1024 photons

Demonstrated potential for bosonic quantum error correction

Abstract

Storing quantum information for an extended period of time is essential for running quantum algorithms with low errors. Currently, superconducting quantum memories have coherence times of a few milliseconds, and surpassing this performance has remained an outstanding challenge. In this work, we report a qubit encoded in a novel superconducting cavity with a coherence time of 34 ms, an improvement of over an order of magnitude compared to previous demonstrations. We use this long-lived quantum memory to store a Schr\"odinger cat state with a record size of 1024 photons, indicating the cavity's potential for bosonic quantum error correction.