Superconducting cavities can reach quality factors exceeding one billion, making them promising candidates for long-lived quantum memories. However, achieving extended coherence times in cavity qubits faces challenges due to their inevitable coupling to a noisy environment.

We introduce a novel niobium cavity controlled via a weakly-coupled transmon and demonstrate a single-photon lifetime surpassing the current state of the art by an order of magnitude [1]. Additionally, we implement a real-time feedback protocol that corrects errors propagating from the transmon to the cavity, allowing us to recover from most dephasing events [2]. These advancements open new avenues for bosonic quantum error correction and for achieving high-fidelity quantum gates on cavity qubits.

[1] O. Milul, B. Guttel et al., PRX Quantum 4, 030336 (2023).
[2] U. Goldblatt et al., preprint at arXiv:2403.02081

*We acknowledge financial support from the European Research Council Starting Investigator Grant Q-CIRC 134847 and the Israel Science Foundation ISF Quantum Science and Technologies Grant 963/19