Alfred B. U’Ren

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A reliable single photon source is a prerequisite for linear optical quantum computation and for secure quantum key distribution. A criterion yielding a conclusive test of the single photon character of a given source, attainable with realistic detectors, is therefore highly desirable. In the context of heralded single photon sources, such a criterion(More)
From quantum computation to quantum key distribution, many quantumenhanced applications rely on the ability to generate pure single-photons. Even though the process of spontaneous parametric downconversion is widely used as the basis for photon-pair sources, the conditions for pure heralded single-photon generation, taking into account both spectral and(More)
Engineering an ideal indistinguishable photon-pair source for optical quantum information processing Radhika Rangarajan a , Luis Edgar Vicent b , Alfred B. U’Ren b & Paul G. Kwiat a a Department of Physics , University of Illinois at Urbana-Champaign , 1110 W Green St., Urbana, IL 61801, USA b Instituto de Ciencias Nucleares, Universidad Nacional Autónoma(More)
Polarization dependence on downconversion emission angle: investigation of the ‘Migdall effect’ Radhika Rangarajan a , Alfred B. U’Ren b & Paul G. Kwiat a a Department of Physics , University of Illinois at Urbana-Champaign , 1110 W Green St., Urbana, IL 61801, USA b Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México , Apartado Postal(More)
We study photon pair generation through scalar spontaneous four-wave mixing in single-mode fibre and for frequency-degenerate pumps; we concentrate on source geometries which fulfil full group velocity matching (GVM), i.e. where the pump, signal and idler propagate at identical group velocities. We discuss two experimental techniques which permit the(More)
Random number generation plays an essential role in technology with important applications in areas ranging from cryptography to Monte Carlo methods, and other probabilistic algorithms. All such applications require high-quality sources of random numbers, yet effective methods for assessing whether a source produce truly random sequences are still missing.(More)
We have designed and implemented a photon-pair source, based on the spontaneous four wave mixing (SFWM) process in a few-mode fiber, in a geometry which permits multiple, simultaneous SFWM processes, each associated with a distinct combination of transverse modes for the four participating waves. In our source: i) each process is group-velocity-matched so(More)
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