-photon state, the method of optical centroid measurement (OCM) was shown to exhibit a resolution enhancement by improving the classical Rayleigh limit by a factor of

1/N

. In this work, the theory of OCM is formulated within the framework of an imaging formalism and is implemented in an exemplary experiment by means of a conventional entangled photon pair source. The expected resolution enhancement of a factor of two is demonstrated. The here presented experiment allows for single-shot operation without scanning or iteration to reproduce the object in the image plane. Thereby, photon detection is performed with a newly developed integrated time-resolving detector array. Multi-photon interference effects responsible for the observed resolution enhancement are discussed and possible alternative implementation possibilities for higher photon number are proposed.

DOI: 10.1364/optica.5.001150

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N

-photon state, the method of optical centroid measurement (OCM) was shown to exhibit a resolution enhancement by improving the classical Rayleigh limit by a factor of

1/N

In this paper we study the resolution of images illuminated by sources composed of

N+1

photons in which one non-degenerate photon is entangled with

N

degenerate photons. The

N

degenerate photons illuminate an object and are collected by an

N

photon detector. The signal from the

N

photon detector is measured in coincidence with the non-degenerate photon giving rise to a ghost image. We discuss the case of three photons in various configurations and generalize to

N+1

. Using the Rayleigh criterion, we find that the system may give an improvement in resolution by a factor of

N

compared to using a classical source. For the case that the

N

-photon number detector is a point detector, a coherent image is obtained. If the

N

-photon detector is a bucket detector, the image is incoherent. The visibility of the image in both cases is 1. In the opposite case in which the non-degenerate photon is scattered by the object, then, using an

N

-photon point detector may reduce the Airy disk by a factor of

N