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Realize super-resolving phase measurement with short-wavelength NOON states by QFC

  Precise measurements are the key to advances in all fields of science. Quantum entanglement shows higher sensitivity than achievable by classical methods. Most physical quantities including position, displacement, distance, angle, and optical path length can be obtained by optical phase measurements. Reducing the photon wavelength of the interferometry can further enhance the optical path length sensitivity and imaging resolution. By quantum frequency up-conversion, we realized a short-wavelength two photon number entangled state. Nearly perfect Hong–Ou–Mandel interference is achieved after both 1547-nm photons are upconverted to 525 nm. Optical phase measurement of two-photon entanglement state yields a visibility greater than the threshold to surpass the standard quantum limit. These results offer new ways for high precision quantum metrology using short wavelength quantum entanglement number state.



FIG. 1. Experimental setup for each experiment. (a) Simplified diagram of the

single-photon source used in experiments; (b) Key module used for frequency

up-conversion. (c) Diagram for QFC of two-photon Fock state.

(d) Setup for up-conversion of both 1547-nm photons to generate the 525-nm

two-photon NOON state and perform phase measurements of this state in a

self-stable tilted Sagnac interferometer.

FIG.4. Experimental results for the generation of 525-nm two-photon NOON

states. (a) HOM interference for up-converted 525-nm photon pair. (b) qauntum conversion efficiency from 1547-nm to 525-nm. (c) and (d) one-photon and two-photon interference patterns as function of rotation angle of the phase plate.

This article was accepted by Physical Review Applied,

zhi-yuan zhou and shi-long liu are contributed equally to this work