Środowiskowe Seminarium z Informacji i Technologii Kwantowych

We consider the estimation of a Hamiltonian parameter of a set of highly photosensitive samples, which are damaged after a few photons Nabs are absorbed. The samples are modelled as a two mode photonic system, where photons simultaneously acquire information on the unknown parameter and are absorbed at a fixed rate. The shot-noise limit implies that arbitrarily intense coherent states can obtain information at a rate that scales at most linearly with Nabs, whereas quantum states with finite intensity can surpass this bound. In particular, few-photon entangled states can overcome arbitrary classical strategies when Nabs is small, and we characterize the quantum advantage as a function of Nabs and N (the number of photons in the quantum state). We also consider the robustness of the advantage under imperfect measurements and finite preparation rate of quantum states. Finally, we consider an implementation of these quantum advantages in cavity QED, where Fock states are both prepared and measured by coupling atomic ensembles to the cavities. In this platform, Dicke superradiance can be exploited for preparing and measuring photonic states fast and with high efficiency.This talk is based on arXiv:2006.12114, joint work with Daniel Malz and Ignacio Cirac.

ZOOM link: https://zoom.us/j/6526721604?pwd=Y0pPdE9vT1hNWWNiZVBMaEVOeHN2dz09