Measurement of the biphoton second-order correlation function with analog detectors.

Area of Science:

• Quantum optics
• Quantum information science

Background:

• Spontaneous parametric down-conversion (SPDC) is a key source for quantum light. Measuring biphoton correlations is vital for quantum technologies. Traditional methods struggle in long-wave spectral ranges due to detector limitations.

Purpose of the Study:

• To propose an experimental scheme and data processing for measuring the normalized second-order correlation function of biphoton fields using analog photodetectors.
• To address challenges in long-wave spectral ranges where single-photon detectors are difficult to implement in both channels.
• To develop methods for discriminating analog detection samples to eliminate noise and obtain accurate correlation function and detector quantum efficiency values.

Main Methods:

• Utilizing analog photodetectors for measuring the normalized second-order correlation function of biphotons from SPDC.
• Developing data processing approaches to discriminate analog detection samples and mitigate noise.
• Demonstrating methods with configurations including two single-photon avalanche photodetectors or a mix of single-photon detectors and photomultiplier tubes.

Main Results:

• A validated experimental scheme and data processing methods for analog detection of biphoton correlations.
• Effective noise discrimination techniques yielding quantitatively true correlation function values.
• Accurate determination of detector quantum efficiency even with analog detection.

Conclusions:

• The proposed methods enable accurate biphoton correlation measurements using analog detectors, particularly beneficial for long-wave quantum SPDC technologies.
• The developed noise discrimination techniques enhance the reliability of measurements when single-photon detectors are not feasible.
• This work provides essential tools for advancing quantum technologies reliant on biphoton characterization.