A long-lived quantum memory using a 3D niobium cavity

Long-lived memory qubits will be essential for future quantum processors

and may significantly reduce the error correction overhead. 3D superconducting

cavities, which can reach quality factors well beyond 1 billion, are a promising

candidate for such quantum memories. However, these high quality factors have

not yet been leveraged to create long-lived quantum memories. This is often

due to a combination of losses induced by two-level systems and decoherence

induced by coupling to a nonlinear ancilla qubit.

In this talk, we present results for a quantum memory realized with a novel

niobium cavity controlled by a weakly-coupled transmon ancilla. We discuss the

use of error-mitigation methods to reduce the effect of cavity dephasing errors.

We show that a single-photon qubit encoded in the cavity achieves lifetimes well

beyond the current state of the art.

* This research was supported by the European Research Council (#134847).