Photon noise correlations in millimeter-wave telescopes

Area of Science:

• Astronomy
• Astrophysics
• Optical Physics

Background:

• Modern millimeter-wave (mm-wave) telescopes increasingly use higher detector pixel densities.
• Overfilling focal planes is becoming practical due to advanced detector architectures and readout techniques.
• Small pixel pitch relative to wavelength and focal ratio can lead to correlated photon noise.

Purpose of the Study:

• To present a method for calculating Hanbury Brown and Twiss (HBT) correlations in detector arrays.
• To extend the HBT correlation calculation to polarization-sensitive detectors.
• To assess the impact of HBT correlations on mm-wave telescope sensitivity and focal plane design.

Main Methods:

• Utilizing a quantum optics formalism to derive HBT correlation calculations.
• Extending the formalism to account for polarization-sensitive detectors.
• Modeling a mm-wave telescope to estimate the sensitivity impact of HBT correlations.

Main Results:

• The Hanbury Brown and Twiss (HBT) effect introduces correlations in photon noise between adjacent detector pixels when pixel pitch is small (p ≲ 1.2Fλ).
• These correlations degrade array-averaged sensitivity, causing it to scale less favorably than the ideal Ndet-1/2 limit.
• The study provides a general prescription for quantifying HBT correlations and their impact on sensitivity.

Conclusions:

• HBT correlations are a significant factor affecting sensitivity in densely packed mm-wave detector arrays.
• Understanding and quantifying these correlations is crucial for optimizing focal plane design.
• The presented formalism aids in designing future mm-wave telescopes with improved sensitivity and performance.