Journal of the Optical Society of America B | 2021
Scheme for sub-shot-noise transmission measurement using a time-multiplexed single-photon source
Abstract
A rather promising result from optical quantum metrology is the ability to achieve sub-shot-noise performance in transmission/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 results from an experiment that uses a multiplexed single-photon source based on pair generation by continuous spontaneous parametric down conversion (SPDC) and a subsequent time multiplexing set-up with a binary division strategy, considering several types of experimental losses. In 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 with coherent sources) and the ultimate quantum limit (achieved with an ideal photon-number Fock state). We also investigate conditions in which threshold detectors can be used and the effect of input light fluctuations in 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 transmission/absorption measurements with reasonable uncertainty using ultra-low light intensity and minimum disruption of biological or other fragile samples.