Imaging and Optical Processing with Entangled Photons

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9970657SalehThe use of nonclassical entangled light is proposed for the investigation and development of a fundamentally new approach to optical imaging. The process of spontaneous parametric downconversion using a laser-pumped nonlinear optical crystal readily creates entangled-light beams, which comprise highly correlated entangled-photon pairs. Previously, we examined the intrinsically nonclassical nature of such beams and we used them to carry out high-accuracy metrology. We propose to examine the potential of this largely untapped area of optics for novel object imaging and analysis applications.The proposed imaging configurations involve the spatiotemporal detection of the entangled photons. which is conveniently performed with readily available single-photon-sensitive charge-coupled-device cameras and avalanche-photodiode detectors. In entangled-photon imaging, the members of each entangled-photon pair are split into two separate optical paths. Each path is individually configured in terms of its optics. The strength of this approach resides in the strong space and time correlations of the pairs - measurements performed on one member of an entangled-photon pair are rapidly reflected in correlation measurements with its partner photon. As an example of the unusual properties of such systems, this feature permits the insertion of an optical element into the path of one of the photons to be manifested in the unaltered partner's path when evaluated in coincidence. Thus, one path can contain the sample object while the other path can contain optical elements such as lenses and apertures to manipulate the image. This can be useful in biological imaging, for example. where it is not always feasible to insert sizable optical elements into the optical path illuminating the sample. Moreover, one can illuminate an object with one optical wavelength while illuminating the optical elements with a different wavelength, thus permitting a unique dual-wavelength-imaging configuration. Furthermore, this configuration can be extended to include broadband downconver-ted light, yielding correlated-photon multi-spectral imaging possibilities. We have carried out preliminary experiments supporting the features of some of these notions.Experimental and theoretical investigations or several forms of entangled-photon imaging are proposed. Unifying principles and intrinsic limitations, such as the sensitivity and resolution, of imaging with entangled light will be elucidated. An expression for the optical transfer function will be derived using realistic assumptions regarding the image detection time and photon flux incident on the sample. Experiments will be conducted to assess the single-photon-sensitive intensified charge-coupled-device camera, which is part of the imaging system. Following this, several experimental arrangements will be investigated, particularly the demonstration and performance evaluation of single-wavelength, and possibly dual-wavelength configurations, as indicated above. Our overall goal is to establish the merits of, and demonstrate the operation of, a highly novel and useful entangled-photon imaging system suitable for a variety of applications in the physical and biological sciences.***