Asymmetry-aided measurement-based quantum repeaters and distributed quantum computing with a decoder-free client

Abstract

Distributed quantum computation needs to move logical qubits across lossy optical links, yet this transmission layer is usually designed separately from the computation it serves. We treat the two together by recognizing that a measurement-based quantum repeater is a two-dimensional code foliated along the transmission axis, so that the dominant channel loss is concentrated on the transmitted sector while the locally measured qubits are largely spared. Matching a code's distance to this structural asymmetry, we show that a rectangular Bacon-Shor subsystem code transmits a logical qubit markedly more efficiently than transmission-unaware encodings. Over continental distances, its cost-optimal repeater density is about an order of magnitude lower than that of a recent $[[48,6,8]]$ benchmark at comparable transmission rate, and roughly half that of a symmetric code of equal size. Moreover, we extend the framework to a central-to-client round trip in which a code-level, distance-preserving code switch joins the transmission legs to the client's computation, and joint decoding of the heterogeneous syndrome record at the central node lets distributed quantum computation proceed with a decoder-free client.