Quantum-enhanced mid-infrared single-photon frequency up-conversion detection with loss and noise resilience

Mid-infrared (MIR) detection remains challenging due to limited detector sensitivity and strong background noise. Frequency up-conversion enables MIR detection with visible-range detectors but suffers from limited robustness and additional noise generated in the nonlinear process. We demonstrate a quantum-enhanced MIR frequency up-conversion detection system that generates strongly non-degenerate, time-correlated photon pairs via spontaneous parametric down-conversion and detects MIR photons under severe loss and noise. With a 62 dB transmission loss and background noise 28 times higher than the detected signal, the quantum signal-to-noise ratio substantially surpasses that of classical photon counting. The system achieves stable signal retrieval under unpredictable noise fluctuations, highlighting its robustness in dynamically varying environments. These results establish a basis for practical sensing and imaging applications of quantum-enhanced MIR detection.