Reusing Erasure-Biased OAM Diffusion as a Storage Resource: A Loop-Buffer Memory and Its Loss Budget

Abstract

Description This theoretical work extends our previous study on erasure-biased orbital angular momentum (OAM) cat-qubits by investigating whether the same diffusion mechanism can be repurposed as a short-term quantum memory. Instead of considering OAM diffusion solely as a transmission impairment, the proposed architecture stores photonic qubits inside a recirculating fiber-loop buffer, where the propagation distance is accumulated through multiple round trips. The work combines: an exact analytical description of OAM diffusion based on Skellam/Bessel statistics; a realistic hardware loss model including optical-switch insertion losses and fiber splices; numerical evaluation of memory lifetime versus hardware loss budget. A central result is that, under the assumption of mode-independent hardware loss, loop losses cancel exactly from the conditional logical error rate. Hardware losses therefore reduce only the probability of successful retrieval, while the logical fidelity of accepted qubits remains governed by the OAM diffusion process. The study also quantifies the engineering requirements necessary for practical implementation, demonstrating that future progress depends primarily on reducing optical-switch losses rather than improving the underlying OAM encoding. This work is intended as a theoretical resource for researchers in photonic quantum information, quantum networking, and quantum memory architectures.