Interferometer

Abstract: We use a 50/50 Sagnac-loop configuration to spatially separate degenerate photon pairs created via four-photon scattering in dispersion-shifted fiber. A Hong-Ou-Mandel dip with visibility> 94 % is observed. c © 2006 Optical Society of America OCIS codes: (270.0270) Quantum optics; (190.4370) Nonlinear optics, fibers. The omnipresence of telecommunication fibers makes the 1550-nm telecom band particularly attractive for quantum information processing (QIP). Indistinguishable photons play a major role in the linear optical quantum computing paradigm [1]. Therefore, a telecom-band indistinguishable photon-pair source is par-ticularly desirable for such QIP tasks. In this paper we present a fibre-based source of indistinguishable photon pairs at a telecom-band wavelength near 1550 nm. We verify the photon pairs ’ indistinguishability by a Hong-Ou-Mandel (HOM) interference experiment, which shows a near-unity HOM-dip visibility of 94.3%, making this source useful for various QIP applications. The experimental setup is depicted in Fig. 1. The dual-pump pulses are prepared by using a similar setup as in Ref. [2]. Briefly, out of the broadband spectrum of a femtosecond laser (repetition rate ∼ 50 MHz), we spectrally carve out our desired pump central wavelengths (λp1 = 1545.95 nm and λp2 = 1555.92 nm, puls