Optimal quantum estimation of the coupling between two bosonic modes
G Mauro D'Ariano, Matteo G A Paris, Paolo Perinotti · Journal of Optics B Quantum and Semiclassical Optics · 2001
We address the problem of the optimal quantum estimation of the coupling parameter of a bilinear interaction, such as the transmittivity of a beamsplitter or the internal phase-shift of an interferometer. The optimal measurement scheme confirms Heisenberg scaling of precision versus the total energy as an unsurpassable bound, but with a largely reduced multiplicative constant.