Quantum cryptography with polarizing interferometers

Sergienko, Migdall, Datla

Alexander V. Sergienko, Alan L. Migdall, Raju V. Datla

Masahiro Kitagawa, M. Kaji, Toshiya Kobayashi

Marek Czachor

Cryptographic scheme proposed by Bennett, Brassard, and Mermin [Phys. Rev. Lett. {\\bf 68}, 557 (1992)] is reformulated in a version involving two polarizing Mach-Zehnder interferometers. Such a form, although physically equivalent to the original one, makes its security explicit, suggestive and easy to explain to non-experts.

Hiroyuki Sasada, Megumi Okamoto

We have theoretically and experimentally studied how a Mach-Zehnder interferometer with an additional mirror transforms a light beam composed of the second lowest transverse modes, ${\mathrm{HG}}_{10},$ ${\mathrm{HG}}_{01},$ ${\mathrm{LG}}_{01},$ and ${\mathrm{LG}}_{0\ensuremath{-}1}$ (HG denotes Hermite-Gaussian mode; LG denotes Laguerre-Gaussian mode). In certain conditions, the interferometer divides the incident beam into the ${\mathrm{HG}}_{10}$ and ${\mathrm{HG}}_{01}$ components as a transverse-mode beam splitter. We propose a practical device involving the two interferometers for quantum cryptography, in which a photon carries two bits corresponding to the polarization and the transverse mode.

Soh Kee Pang