Two-Stage Quantum-Classical Distribution Network Reconfiguration via Cycle-Edge Encoding

Distribution network reconfiguration (DNR) is a combinatorial optimization problem that seeks a low-loss network topology subject to topological and electrical operating constraints. In this work, we propose a two-stage quantum-classical method for DNR. First, an iterative linear-ramp Quantum Alternating Operator Ansatz (LR-QAOA) searches topologically feasible subspaces constructed using a novel cycle-edge encoding. The encoding guarantees that every represented configuration is a spanning tree while allowing the size and coverage of each subspace to be adjusted to the available qubit budget. Second, the resulting sample distribution is used to guide a mixed-integer second-order-cone programming (MISOCP) solver. The method is evaluated on six distribution networks ranging from 33 to 417 buses through simulation and execution on trapped-ion quantum hardware. Across all six test systems, the MISOCP solver guided by hardware-derived distributions reaches an incumbent within 1% of the best-known solution in less median solver time than the corresponding unguided solver.