Scheme for sub-shot-noise transmission measurement using a time multiplexed single-photon source

TL;DR

This paper demonstrates through simulation that a time-multiplexed single-photon source can achieve sub-shot-noise transmission measurements, enabling more precise optical absorption measurements with minimal light intensity.

Contribution

The work introduces a simulation-based scheme using a multiplexed SPDC photon source and binary temporal division to attain sub-shot-noise performance without number-resolving detectors.

Findings

Sub-shot-noise performance achieved with improvement factors of 1.5 to 2.

Effective even with threshold detectors, reducing experimental complexity.

Potential for minimally invasive biological and material measurements.

Abstract

A promising result from optical quantum metrology is the ability to achieve sub-shot-noise performance in transmission or absorption measurements. This is due to the significantly lower uncertainty in light intensity of quantum beams with respect to their classical counterparts. In this work, we simulate the outcome of an experiment that uses a multiplexed single-photon source based on pair generation by continuous spontaneous parametric down conversion (SPDC) followed by a time multiplexing set-up with a binary temporal division strategy, considering several types of experimental losses. With such source, the sub-Poissonian statistics of the output signal is the key for achieving sub-shot-noise performance. We compare the numerical results with two paradigmatic limits: the shot-noise limit (achieved using coherent sources) and the quantum limit (obtained with an ideal photon-number Fock state as the input source). We also investigate conditions in which threshold detectors can be used, and the effect of input light fluctuations on the measurement error. Results show that sub-shot-noise performance can be achieved, even without using number-resolving detectors, with improvement factors that range from 1.5 to 2. This technique would allow measurements of optical absorption of a sample with reasonable uncertainty using ultra-low light intensity and minimum disruption of biological or other fragile specimens.