Scalable Imaging of Superresolution

Abstract

N00N states-maximally path-entangled states of N photons-exhibit spatial interference patterns sharper than any classical interference pattern. This is known as superresolution. However, even given perfectly efficient number-resolving detectors, the detection efficiency of all previous measurements of such interference would decrease exponentially with the number of photons in the N00N state, often leading to the conclusion that N00N states are unsuitable for spatial measurements. A technique known as the "optical centroid measurement" has been proposed to solve this and has been experimentally verified for photon pairs; here we present the first extension beyond two photons, measuring the superresolution fringes of two-, three-, and four-photon N00N states. Moreover, we compare the N00N-state interference to the corresponding classical superresolution interference. Although both provide the same increase in spatial frequency, the visibility of the classical fringes decreases exponentially with the number of detected photons. Our work represents an essential step forward for quantum-enhanced measurements, overcoming what was believed to be a fundamental challenge to quantum metrology.

Imaging with quantum states of light

“…However it was suggested that to detect such interference patterns one could simply proceed to optical centroid measurements of the N detected photons of the NOON state [142]. This method was later implemented [146] for 2 photon NOON states and for up to 4 photon NOON states [147,148]. Finally, it has been shown that multiphoton interference with independent single photon light sources can also lead to a similar super-resolved interference pattern [149], without using path entangled states.…”