Heisenberg-Limited Precision in Coherent Photonic ISAR: A Hybrid Simulator Approach for Quantum-Enhanced Polarimetric Target Identification

We present a GPU-accelerated hybrid simulator for a coherent photonic Inverse Synthetic Aperture Radar (ISAR) system that incorporates quantum-metrology–based phase enhancement. The framework unifies electromagnetic scattering (Physical Optics augmented with Physical Theory of Diffraction and multi-bounce models), realistic photonic and atmospheric impairments (Jones-matrix misalignment, IQ imbalance, and ITU-R P.676-12 loss), and a loss-degraded N = 2 NOON-state quantum receiver. Under identical photon budgets (~3.2 × 10⁴ photons per pulse), the simulated quantum receiver achieves a 2.48×–3.13× reduction in phase variance below the Standard Quantum Limit (≈3.95–4.96 dB), consistent with the predicted loss-degraded Heisenberg scaling (η_tot ≈ 0.83). This sub-SQL phase precision directly improves polarimetric feature extraction—Pauli decomposition, entropy, and alpha-angle analysis—enabling discrimination between a conventional aircraft (cross-pol ≈ 23.0 %) and a low-observability platform (cross-pol ≈ 14.9 %). A complete polarimetric scan (1024 aspects × 4 polarizations × 2 targets) executes within seconds on a laptop GPU, establishing a practical route toward near-term experimental validation of quantum-enhanced photonic radar<p></p>