Force Sensing in a Recoverable Bosonic Quantum Memory

Abstract

In continuous-variable quantum information, sensing and quantum error correction in the same mode face an intrinsic trade-off: sensors must accumulate weak external displacements, whereas bosonic codes typically suppress such shifts as errors. Here, we establish compatibility by constructing finite-energy bosonic codes that enable a single oscillator to sense an external force while actively protecting an unknown logical qubit. By encoding logical amplitudes across discrete wave-packet sites and capturing the force signal in a shared internal coordinate, we achieve an endpoint probe readout that is independent of the logical state under continuous photon loss $\gamma$. Crucially, binomial site recovery cancels packet-dependent probe distortions alongside logical errors: for a $(2r+2)$-packet code, memory infidelity is suppressed to $O(\gamma^{r+1})$ while residual memory-probe correlations scale as $O(\gamma^{r+2})$. Finally, superconducting quantum circuit benchmarks under competing photon-number dephasing and Kerr nonlinearity identify preferred encoding regimes for hardware implementation.