Suppressing error propagation in bosonic qubits using real-time feedback

Bosonic qubits encoded in superconducting cavities are a promising approach for realizing quantum memories and bosonic codes with built-in protection against decoherence. However, a noisy ancilla qubit is required to encode and manipulate the bosonic qubit. As a result, ancilla errors propagate to the cavity, dephasing the cavity-encoded qubit. This error propagation presented a major limitation in previous experiments with bosonic qubits.

We will present a novel error mitigation protocol based on repeated measurements and real-time feedback to suppress this error propagation. We will demonstrate the effect of this procedure on the coherence time of the bosonic qubit.