# PPLN waveguide for quantum communication

 Authors: S Tanzilli, W Tittel, H De Riedmatten, H Zbinden, P Baldi, M De Micheli, D B Ostrowsky, N Gisin European Physical Journal D 18, 155–160 (2002) http://dx.doi.org/10.1140/epjd/e20020019 We report on energy-time and time-bin entangled photon-pair sources based on a periodically poled lithium niobate (PPLN) waveguide. Degenerate twin photons at 1314 nm wavelength are created by spontaneous parametric down-conversion and coupled into standard telecom fibers. Our PPLN waveguide features a very high conversion efficiency of about 10(-6), roughly 4 orders of magnitude more than that obtained employing bulk crystals [1]. Even if using low power laser diodes, this engenders a significant probability for creating two pairs at a time - all important advantage for some quantum communication protocols. We point out a simple means to characterize the pair creation probability in case of a pulsed pump. To investigate the quality of the entangled states, we perform photon-pair interference experiments, leading to visibilities of 97% for the case of energy-time entanglement and of 84% for the case of time-bin entanglement. Although the last figure must still be improved, these tests demonstrate the high potential of PPLN waveguide based sources to become a key element for future quantum communication schemes. ppln.pdf

# BibTeX Source

@ARTICLE{Tanzilli2002,
author = {Tanzilli, S. and Tittel, W. and De Riedmatten, H. and Zbinden, H.
and Baldi, P. and De Micheli, M. and Ostrowsky, D. B. and Gisin,
N.},
title = {PPLN waveguide for quantum communication},
journal = {European Physical Journal D},
year = {2002},
volume = {18},
pages = {155--160},
number = {2},
abstract = {We report on energy-time and time-bin entangled photon-pair sources
based on a periodically poled lithium niobate (PPLN) waveguide. Degenerate
twin photons at 1314 nm wavelength are created by spontaneous parametric
down-conversion and coupled into standard telecom fibers. Our PPLN
waveguide features a very high conversion efficiency of about 10(-6),
roughly 4 orders of magnitude more than that obtained employing bulk
crystals [1]. Even if using low power laser diodes, this engenders
a significant probability for creating two pairs at a time - all
important advantage for some quantum communication protocols. We
point out a simple means to characterize the pair creation probability
in case of a pulsed pump. To investigate the quality of the entangled
states, we perform photon-pair interference experiments, leading
to visibilities of 97% for the case of energy-time entanglement and
of 84% for the case of time-bin entanglement. Although the last figure
must still be improved, these tests demonstrate the high potential
of PPLN waveguide based sources to become a key element for future
quantum communication schemes. },
cl = {INST ETUDES SCI, CARGESE, FRANCE},
ct = {Conference on Quantum Interference and Cryptographic Keys - NovelEOLEOLPhysics