Enhanced frequency estimation by non-Gaussianity of Fock states

Abstract: Leveraging the unique quantum properties of non-Gaussian states is crucial for advancing continuous variable quantum technologies. Recent experimental advancements in generating non-Gaussian states, coupled with theoretical findings of their superior performance in quantum information protocols compared to Gaussian states, motivate this investigation. This work investigates the impact of non-Gaussianity on the precision of frequency estimation using a quantum probe. We analyze a single bosonic mode and its non-Gaussian excited states as a system, while the frequency estimation is investigated by explicitly computing the quantum Fisher information. Our results demonstrate a significant enhancement in the quantum Fisher information for non-Gaussian states compared to Gaussian states with equivalent second-order moments. Importantly, we find that the increased quantum Fisher information achieved with non-Gaussian states outweighs their higher energetic cost compared to the Gaussian ground state. We also briefly discuss two photonic non-Gaussian state generation schemes: interaction with an ancillary system and the use of photon number measurement on the photonic probe.