Creating and sharing knowledge for telecommunications

Enabling Quantum Communications through Accurate Photons Polarization Control

Almeida, A. ; Muga, N. J. ; Silva, N. A. ; Stojanovic, A. ; André, P.S ; Pinto, A. N. ; Mora, J. M. ; Capmany, J. C.

Enabling Quantum Communications through Accurate Photons Polarization Control, Proc RIAO/OPTILAS, Porto, Portugal, Vol. 1, pp. 1 - 8, July, 2013.

Digital Object Identifier: 10.1117/12.2026208

The rapid increase on the information sharing around the world, leads to an utmost requirement for capacity
and bandwidth. However, the need for security in the transmission and storage of information is also of major
importance. The use of quantum technologies provides a practical solution for secure communications systems.
Quantum key distribution (QKD) was the rst practical application of quantum mechanics, and nowadays it
is the most developed one. In order to share secret keys between two parties can be used several methods of
encoding. Due to its simplicity, the encoding into polarization is one of the most used. However, when we use
optical bers as transmission channels, the polarization su ers random rotations that may change the state of
polarization (SOP) of the light initially sent to the ber to a new one at the output. Thus, in order to enable
real-time communication using this encoding method it is required the use of a dynamic control system. We
describe a scheme of transmission of quantum information, which is based in the polarization encoding, and that
allows to share secret keys through optical bers without interruption. The dynamic polarization control system
used in such scheme is described, both theoretically and experimentally. Their advantages and limitations for
the use in quantum communications are presented and discussed.