Experimental Quantum Target Detection Approaching the Fundamental Helstrom Limit.

Area of Science:

• Quantum optics
• Quantum sensing
• Quantum information science

Background:

• Quantum target detection leverages entanglement for enhanced sensing.
• The Helstrom limit, a theoretical benchmark, remains largely unreached due to challenges in implementing optimal measurements.
• Previous experimental demonstrations have not achieved single-shot detection limits.

Purpose of the Study:

• To experimentally demonstrate quantum target detection, or quantum illumination, in the single-photon limit.
• To implement the optimum measurement for quantum illumination.
• To explore the quantum advantage in various parameter regimes, including regions where classical schemes fail.

Main Methods:

• Utilizing maximally entangled photon pairs, with one photon serving as the probe signal.
• Implementing the theoretically derived optimum measurement at the receiver.
• Testing the quantum illumination scheme across different parameter spaces.

Main Results:

• Experimental demonstration of quantum illumination at the single-photon level.
• Achieved a quantum advantage exceeding classical limits by up to 40%.
• Verified the existence of quantum advantage even in parameter regions where conventional illumination is ineffective.
• Approached the quantum detection limit set by the Helstrom limit.

Conclusions:

• Quantum illumination offers a significant advantage over classical target detection methods.
• The implemented optimal measurement strategy is crucial for achieving quantum gains.
• This work highlights the practical potential of quantum illumination for advanced sensing applications.