Unitary metrology with linear optics.

The linear optics-based devices became a subject of an intense research as a platform for quantum algorithms. Here we present an all-optical experimental realization of the unitary Fourier transformation-based phase estimation protocol having a wealth of applications in quantum metrology. The developed setup made of beam splitters, mirrors and phase shifters opens route to reliable implementation of the moderate scale quantum algorithms thus establishing an easily accessible platform for quantum computation.