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Nonlinear Optics

Applications of Nonlinear Optics in Quantum Imaging and Quantum Communication

Robert W. Boyd, Heedeuk Shin, Mehul Malik, Colin O’Sullivan, Kam Wai Clifford Chan, Hye Jeong Chang, Daniel J. Gauthier, Anand K. Jha, Jonathan Leach, Sangeeta Murugkar, Brandon Rodenburg

Published Jan 1, 2011• 2 citations
Publisher

Abstract

The nonlinear optical process of spontaneous parametric downconversion is a standard procedure for generating entangled photons. Entanglement is a crucial resource for quantum information studies. We describe our recent results including the application of entangled photons to superresolution and to quantum communication.
DOI
10.1364/nlo.2011.nwc2

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Entangled photons, generated by spontaneous parametric downconversion from a second-order nonlinear crystal, present a rich potential for imaging and image-processing applications. Since this source is an example of a three-wave mixing process, there is more flexibility in the choices of illumination and detection wavelengths and in the placement of object(s) to be imaged. Moreover, this source is entangled, a fact that allows for imaging configurations and capabilities that cannot be achieved by use of classical sources of light. We examine a number of imaging and image-processing configurations that can be realized with this source. The formalism that we utilize facilitates the determination of the dependence of imaging resolution on the physical parameters of the optical arrangement.
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Based on quasi-phase-matching (QPM) theory, nonlinear photonic crystals (NPCs) are capable of realizing efficient spontaneous parametric downconversion (SPDC) for the generation of photonic entangled states. However, the traditional electric field poling techniques employed in NPC fabrication often result in non-negligible processing errors of a few hundred nanometers, thus impeding the production of quantum photon pairs as intended. In this work, we investigate the SPDC photon pairs generated in a laser-poled lithium niobate (LN) NPC. By using the recently developed laser poling technique, the processing error of the NPC is substantially reduced to approximately 15 nm. Consequently, the coincidence counts of the generated photon pairs in the experiment reach 83.6% of the designed value. Our result paves the way for on-demand production of high-quality quantum sources, which has potential applications in quantum communications and quantum computations.