Quantum Sensing with Fiber Bragg Grating Sensors

Optical quantum metrology takes advantage of the reduced noise properties of quantum states of light for enhancing the sensitivity of measurements beyond the shot noise limit. While there have been many proof-of-principle implementations of quantum sensors, it is important to extend their applicability to practical sensing devices such as Fiber Bragg Grating sensors (FBGs). These sensors can detect small perturbations to the fiber core's refractive index that result from local strain or deformations, thus making them ideal for applications that require an accurate measure of temperature, strain, or vibrations. We show that interfacing two mode squeezed states (twin beams) of light with FBGs can enhance their sensitivity beyond the equivalent classical configuration using coherent state of light. Through the use of specially designed FBGs with a resonance near the wavelength of our twin beams, we implement a configuration based on two FBGs, one for each of the twin beams, for common noise rejection. A modulation signal is applied to the FBGs to characterize the response of the system to common background noise. Additionally, we measure the intensity difference noise of the light reflected by each of the FBGs to characterize the degree of quantum enhancement and show an enhancement in signal-to-noise (SNR) when we use twin beams to probe the FBGs as compared to probing with coherent states.