Hybrid Quantum-Classical Workflow Evaluates Antenna Radiated Power Metrics with 10^{-3} Relative Error

The arXiv preprint by Hiroaki Ominato details an end-to-end workflow that preconditions finite-element matrices from Maxwell's equations, applies a quantum linear system solver, and measures antenna-specific observables. Numerical validation used an axisymmetric coax-fed monopole, producing relative errors of order 10^{-3} versus classical FEM solutions for total radiated power and dielectric/conductive losses under idealized noise-free conditions. This approach directly addresses the measurement bottleneck that erodes quantum speedup when extracting classical solution vectors. Prior quantum EM work focused on scattering parameters; the new observables enable practical design metrics such as efficiency and directivity without tomography overhead. The method assumes fault-tolerant hardware with sufficient logical qubits, aligning with HHL algorithm extensions and recent quantum linear solver hardware demonstrations. Limitations include idealized simulation and small problem size; scaling to three-dimensional broadband antennas will require preconditioners that preserve quantum advantage while controlling condition numbers. Next milestones involve integration with variational quantum eigensolvers for material optimization and hardware tests on early error-corrected devices targeting 10^4-element meshes.