Superconducting Cavity Qubit with Tens of Milliseconds Single-Photon Coherence Time

Storing quantum information for an extended period of time is essential for running quantum algo-rithms 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 single-photon qubit encoded in a novel superconducting cavity with a coherence time of 34 ms, representing an order of magnitude improvement compared to previous demonstrations. We use this long-lived quantum memory to store a Schrodinger cat state with a record size of 1024 photons, indicating the cavity's potential for bosonic quantum error correction.