Bound for Gaussian-state quantum illumination using a direct photon measurement.

Area of Science:

• Quantum Information Science
• Quantum Optics
• Quantum Metrology

Background:

• Establishing feasible measurement bounds is crucial for advancing quantum information protocols.
• Quantum illumination protocols leverage quantum entanglement to enhance sensing capabilities.
• Performance evaluation often relies on signal-to-noise ratio and detection strategies.

Purpose of the Study:

• To present analytic measurement bounds for quantum illumination utilizing Gaussian states.
• To compare the performance of different quantum states (TMSV, coherent, CCT) under various detection schemes.
• To investigate the impact of detection methods (on-off, PNR) and information approaches (coincidence counting, Fisher information) on quantum illumination.

Main Methods:

• Analytic derivation of measurement bounds for quantum illumination with Gaussian states.
• Performance evaluation using signal-to-noise ratio for on-off and photon number resolving (PNR) detections.
• Application of the Fisher information approach, incorporating all counting probabilities, including non-detection events.

Main Results:

• For coincidence counting, the two-mode squeezed vacuum (TMSV) state generally outperformed coherent and classically correlated thermal (CCT) states.
• Coherent states demonstrated superior performance over TMSV states with increasing signal mean photon number under on-off detection.
• The Fisher information approach enhanced performance, with TMSV still leading, but CCT states surpassing TMSV under specific on-off detection conditions.

Conclusions:

• Analytic bounds for quantum illumination with Gaussian states provide crucial insights into protocol feasibility.
• Detection strategies significantly influence performance, with hybrid PNR and on-off detection offering comparable results to dual PNR detection.
• The choice of quantum state and detection method critically impacts the effectiveness of quantum illumination systems.