Wavelength-multiplexed distribution of highly entangled photon-pairs over optical fiber

Abstract

We report the first experimental demonstration of wavelength-multiplexed entanglement distribution over optical fiber. Forty-four channels of polarization-entangled photon-pairs were produced from a single pulse-pumped, short periodically-poled lithium niobate waveguide and distributed over 10 km of dispersion-shifted optical fiber. Entanglement fidelities of the distributed photon-pairs exceeded 0.86 for all selected channels.

Multi-channel entanglement distribution using spatial multiplexing from four-wave mixing in atomic vapor

“…It was also shown that entanglement can be distributed to many parties for QKD using wavelength multiplexing in optical fibers [14], effectively increasing the number of available channels from a single resource. In our experiment, we perform CV measurements on multi-spatial-mode light containing nonclassical correlations, demonstrating spatial multiplexing as a resource for distributing secure keys rather than wavelength multiplexing.…”

Multi-user distribution of polarization entangled photon pairs

“…In order to evaluate the quality of the distributed entanglement and assess the effect of the various demultiplexers, we measure the following parameters: the visibility in the natural and the diagonal bases, V = (C max − C min )/(C max + C min ), where C max and C min are respectively the maximum and minimum number of coincidences when one of the polarisation basis angles is changed; the violation of the CHSH inequality, which is quantified by the Bell parameter S; and the brightness (21,27) 0.82 ± 0.04 0.77 ± 0.04 2.25 ± 0.07 216 0.20 0.970 ± 0.053 AWG (23,25) 0.77 ± 0.04 0.74 ± 0.05 2.10 ± 0.10 149 0.064 0.972 ± 0.059 AWG (22,26) 0.79 ± 0.05 0.66 ± 0.05 2.00 ± 0.10 116 0.079 0.906 ± 0.066 DGFT (23,25) 0.79 ± 0.05 0.82 ± 0.05 2.30 ± 0.10 108 0.030 1.000 ± 0.072 DGFT (22,26) 0 B. The results of our measurements are given in Table I.…”

“…In this case, the broad bandwidth of photon a) Electronic mail: isabelle.zaquine@telecom-paristech.fr pairs produced by spontaneous parametric down conversion can allow for entanglement distribution to multiple user pairs from a single source using wavelength division multiplexing techniques. This possibility has been explored in several recent works [22][23][24][25][26] , while further work is in progress to integrate these devices 27 and to design flexible optical networks based on such sources 28 . In view of the wide use of wavelength division multiplexing in quantum networks for practical applications, it is essential to be able to properly test the employed demultiplexing technologies and quantify their effect to the quality of the distributed entanglement 29 .…”

Emission of orbital-angular-momentum-entangled photon pairs in a nonlinear ring fiber utilizing spontaneous parametric down-conversion

“…Entanglement is indispensable also for quantum communication protocols that, among others, include quantum teleportation [8] and secured quantum key distribution networks [9,10]. Systems for wavelength-division multiplexing that allow one to distribute polarization entangled photons among multiple users [11,12] serve as typical examples.…”

“…Such modes have been theoretically studied [29,30] and experimentally characterized recently [29] using a ring or vortex geometry (concentric rings) of optical fibers. This geometry allows one to separate modes of the LP 11 family that differ in their effective refractive indices. This results in their stable propagation with a low ratio of crosstalk for lengths over 1 km.…”