Photonic polarization gears for ultra-sensitive angular measurements
Vincenzo D’Ambrosio, Nicolò Spagnolo, Lorenzo Del Re +7 more
Quantum metrology bears a great promise in enhancing measurement precision, but is unlikely to become practical in the near future. Its concepts can nevertheless inspire classical or hybrid methods of immediate value. Here we demonstrate NOON-like photonic states of m quanta of angular momentum up to m=100, in a setup that acts as a ‘photonic gear’, converting, for each photon, a mechanical rotation of an angle θ into an amplified rotation of the optical polarization by mθ, corresponding to a ‘super-resolving’ Malus’ law. We show that this effect leads to single-photon angular measurements with the same precision of polarization-only quantum strategies with m photons, but robust to photon losses. Moreover, we combine the gear effect with the quantum enhancement due to entanglement, thus exploiting the advantages of both approaches. The high ‘gear ratio’ m boosts the current state of the art of optical non-contact angular measurements by almost two orders of magnitude. Beating the standard measurement limits is a goal of metrology, as it would allow for more precise estimation of physical quantities. Borrowing concepts from NOON-state quantum metrology, this work presents a single-photon scheme to measure rotation angles of light with super-resolution precision.
arXiv:1306.1606•Nature Communications•Sep 18, 2013•356 citations