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Optics Express

A versatile waveguide source of photon pairs for chip-scale quantum information processing

Jun Chen, Aaron J. Pearlman, Alexander Ling, Jingyun Fan, Alan L. Migdall

Published Apr 8, 2009• 75 citations
Publisher

Abstract

We demonstrate a bright, bandwidth-tunable, quasi-phase-matched single-waveguide source generating photon pairs near 900 nm and 1300 nm. Two-photon coincidence spectra are measured at a range of operating temperatures of a periodically-poled KTiOPO(4) (PPKTP) waveguide, which supports both type-0 and type-II spontaneous parametric down-conversion. We map out relative contributions of two-photon to one-photon fluorescence for a range of operating parameters. Such a versatile device is highly promising for future chip-scale quantum information processing.

DOI
10.1364/oe.17.006727

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We demonstrate a bright, bandwidth-tunable, quasi-phase-matched single-waveguide source generating photon pairs near 900 nm and 1300 nm. Two-photon coincidence spectra are measured at a range of operating temperatures of a periodically-poled KTiOPO(4) (PPKTP) waveguide, which supports both type-0 and type-II spontaneous parametric down-conversion. We map out relative contributions of two-photon to one-photon fluorescence for a range of operating parameters. Such a versatile device is highly promising for future chip-scale quantum information processing.
We present a systematic study of a correlated photon-pair source based on a periodically-poled KTiOPO4 (PPKTP) waveguide. The waveguide was fabricated on a KTiOPO4 crystal supporting type-II parametric down-conversion. In addition, periodic poling was applied along the waveguide to quasi-phase-match the type-0 down-conversion process. The design pump wavelength is 532 nm, and the wavelengths of the down-converted, correlated photons are around 900 nm and 1300 nm. We examine the two-photon correlation spectra and singlephoton spectra at a variety of temperature and power settings for both type-0 and type II down-conversion processes. Our study shows that the waveguide source has a number of advantages compared to its bulk-crystal counterpart, including higher spectral brightness, narrower emission bandwidth and single spatial-mode output. With greatly simplified engineering, this compact, highly efficient, low photon-loss, and cost-effective waveguide source of correlated photon pairs is promising for future chip-scale quantum information processing applications.
We demonstrate efficient generation of photon pairs at 1316 nm in a fiber-coupled type-II phase-matched Rb-indiffused waveguide in periodically poled KTiOPO(4). The integrated waveguide source has a pair production rate of 2 x 10(7)/s/mW in a 1.08-nm bandwidth, in good agreement with a theoretical model that takes into account the transversal momentum imparted on the phase matching function by the waveguide. We achieve a Hong-Ou-Mandel quantum-interference visibility of 98.2% after subtraction of accidental coincidences, representing the highest reported value for a waveguide-based photon-pair source.
We investigate the dual generation of type-0 and type-II spontaneous parametric down conversions (SPDCs) within a single periodically poled rubidium-doped KTiOPO 4 (PPRKTP) waveguide. By coupling a 45° linearly polarized pump laser into the waveguide, both SPDC processes are concurrently excited: type-0 SPDC process is facilitated via third-order quasi-phase matching (QPM) utilizing the nonlinear coefficient d 33 , while type-II SPDC process employs first-order QPM with the nonlinear coefficient d 24 . This dual-SPDC scheme holds potential for applications in quantum communication protocols targeting the telecommunication wavelength.
We report the observation of correlated photon pairs generated by spontaneous parametric downconversion of a 400-nm pump pulse in a quasi-phase-matched KTiOPO(4) nonlinear waveguide. The highest ratio of coincidence to single-photon count rates observed near 800 nm exceeds 18%. This suggests that nonlinear waveguides will be a promising source of correlated photons for metrology and quantum information processing applications. We also discuss possibilities of controlling the spatial characteristics of the downconverted photons produced in multimode waveguide structures.
As optical quantum information processing protocols and experiments become increasingly more complex, integrated optics provide a small and robust alternative to traditional bulk optics. Specifically, waveguide technology allows for the creation of bright single-photon sources based on the fact that photon pairs can be created at any location along the waveguide. For our goals, we are working on the characterization of a highly nondegenerate Spontaneous Parametric Down-Conversion (SPDC) waveguide source on a periodically poled KTP (PPKTP) crystal. Our current waveguide source uses type-II phase-matching to create collinear signal and idler photons at 1550 nm and 810 nm, respectively, with the promise of generating simultaneous time-bin and polarization entanglement in future iterations. Our intended source application is for use in quantum key distribution and superdense teleportation protocols between a space platform and collection telescopes on Earth.