Enhanced resolution in lossy phase estimation by optical parametric amplification

In the optical sensing context one of the main challenge is to design and implement novel techniques of sensing optimized to work in a lossy scenario, in which effects of environmental disturbances can destroy the benefits deriving from the adoption of quantum resources. Here we describe the experimental implementation of a protocol based on the process of optical parametric amplification to boost interferometry sensitivity in the presence of losses in a minimally invasive scenario. By performing the amplification process on a microscopic probe after the interaction with the sample, we can beat the losses detrimental effect on the phase measurement which affects the single photon state after its interaction with the sample, and thus improve the achievable sensitivity.