Heisenberg scaling precision in multi-mode distributed quantum metrology

We propose an Nphoton Gaussian measurement scheme which allows the estimation of a parameter \varphiencoded into a multi-port interferometer with a Heisenberg scaling precision (i.e. of order 1/N. In this protocol, no restrictions on the structure of the interferometer are imposed other than linearity and passivity, allowing the parameter \varphito be distributed over several components. In all previous proposals Heisenberg scaling...