Signal detection using biphotons and potential application in axion-like particle search

TL;DR

This paper introduces a quantum optical system utilizing biphoton correlations to detect minute changes in photon number, offering high sensitivity for applications like axion-like particle searches in physics.

Contribution

It presents a novel optical detection method based on biphoton correlation that can sense small photon number changes without affecting the mean displacement, enhancing detection precision.

Findings

High sensitivity detection of photon number changes

Utilizes quantum correlation for low-noise measurements

Potential application in axion-like particle searches

Abstract

This paper presents a new optical system for detecting light signals associated with the change in incoming photon number. The system employs quantum correlation of photon pairs created via spontaneous parametric down-conversion (SPDC). The signal, if present, will perturb the flux of the incident photon stream. The perturbed photon stream is first projected through a birefringent crystal where SPDC occurs, converting a single high-energy photon into a pair of low energy photons. The photons in each pair eventually arrive at separate detectors. By examining the biphoton correlation using the probability distribution of the photons at the detectors, which varies depending on the displacement of the main pump photon stream and the change in the number of photons, the small optical displacement of the photon stream and its variance can be determined. The change in incident photon number, in other words, the presence of light signal does not influence the average of the measured optical displacement values. Nevertheless, the change in optical displacement measurement variance when the number of incident photons has changed detects the light signal. This optical setup enables the detection of light signals with low noise and remarkably high precision and sensitivity using quantum correlation. The proposed technique has potential application for axion-like particle search in experimental high energy physics.