SIMULTANEOUS DISTRIBUTION OF TWO QUANTUM KEYS BY TRANSMITTING SINGLE PHOTONS WITH WAVELENGTHS OF 780 NM AND 850 NM THROUGH ONE FREE-SPACE QUANTUM CHANNEL
D. B. Tretyakov, A. V. Kolyako, A. S. Pleshkov, I. I. Ryabtsev, I. G. Neizvestny
A. V. Rzhanov Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: quantum communication, BB84 protocol, photon polarization coding, single-photon detectors
Abstract
A method for increasing the quantum key distribution rate in free-space quantum communication lines by simultaneously transmitting single photons with wavelengths of 780 nm and 850 nm through one quantum channel has been proposed and implemented experimentally. Our laboratory system has demonstrated an approximately twofold increase in the "sifted" quantum key distribution rate using two setups operating at wavelengths of 780 nm and 850 nm and transmitting photons through one 23-cm-long quantum channel. The "sifted" quantum key distribution rate and the quantum bit error rate for a wavelength of 780 nm are found to be equal to 11502 ± 290 bits/s and 2.4 ± 0.4%, and the corresponding values for a wavelength of 850 nm are 10627 ± 290 bits/s and 3.9 ± 0.5%.
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