Sub-shot-noise shadow sensing with quantum correlations

Area of Science:

• Quantum optics
• Quantum metrology
• Photonics

Background:

• Classical position measurements are limited by the shot-noise limit due to the quantized nature of light.
• Quantum states offer potential for enhanced measurement precision beyond classical limitations.

Purpose of the Study:

• To demonstrate a simple quantum sensing scheme for sub-shot-noise position measurement.
• To measure the position of a shadow at the single-photon level with enhanced precision.

Main Methods:

• Utilized split-detection of quantum correlations from bi-photon pairs generated via parametric downconversion.
• Employed an electron multiplying CCD (EMCCD) camera as a split-detector.
• Analyzed correlated and uncorrelated photon signals to quantify noise reduction.

Main Results:

• Achieved position sensitivity exceeding the shot-noise limit.
• Observed significant noise reduction, improving position sensitivity by up to 17% (0.8 dB).
• Demonstrated a scalable improvement with detector quantum efficiency.

Conclusions:

• The developed quantum correlation technique enables sub-shot-noise position measurements.
• This straightforward approach is compatible with existing shadow-sensing methods.
• Quantum sensing provides a viable pathway to overcome classical measurement limitations.