An integrated quantum photonic sensor based on Hong-Ou-Mandel interference

TL;DR

This paper introduces a novel integrated quantum photonic sensor utilizing Hong-Ou-Mandel interference in coupled photonic crystal cavities, capable of detecting minute forces and refractive index changes with low power consumption.

Contribution

It presents a new Fock state optical sensor architecture based on coupled cavities acting as an effective beam splitter, enabling high-sensitivity measurements without spectral resolution.

Findings

Detects forces as small as 10^{-7} Newtons

Measures refractive index changes of one part per million

Operates with extremely low input power of 10^{-10}W

Abstract

Photonic-crystal-based integrated optical systems have been used for a broad range of sensing applications with great success. This has been motivated by several advantages such as high sensitivity, miniaturization, remote sensing, selectivity and stability. Many photonic crystal sensors have been proposed with various fabrication designs that result in improved optical properties. In parallel, integrated optical systems are being pursued as a platform for photonic quantum information processing using linear optics and Fock states. Here we propose a novel integrated Fock state optical sensor architecture that can be used for force, refractive index and possibly local temperature detection. In this scheme, two coupled cavities behave as an "effective beam splitter". The sensor works based on fourth order interference (the Hong-Ou-Mandel effect) and requires a sequence of single photon pulses and consequently has low pulse power. Changes in the parameter to be measured induce variations in the effective beam splitter reflectivity and result in changes to the visibility of interference. We demonstrate this generic scheme in coupled L3 photonic crystal cavities as an example and find that this system, which only relies on photon coincidence detection and does not need any spectral resolution, can estimate forces as small as $10^{-7}$ Newtons and can measure one part per million change in refractive index using a very low input power of $10^{-10}$W. Thus linear optical quantum photonic architectures can achieve comparable sensor performance to semiclassical devices.