Authors: Perarnau-Llobet, M.; Gonzalez-Tudela, A.; Cirac, J., I
Journal: QUANTUM SCIENCE AND TECHNOLOGY
Publication date: 2020/03/01
Abstract: We develop general tools to characterise and efficiently compute relevant observables of multimode N-photon states generated in nonlinear decays in one-dimensional waveguides. We then consider optical interferometry in a Mach-Zender interferometer where a d-mode photonic state enters in each arm of the interferometer. We derive a simple expression for the quantum Fisher information in terms of the average photon number in each mode, and show that it can be saturated by number-resolved photon measurements that do not distinguish between the different d modes.