Continuous Control of Random Polarization Rotations for Quantum Communications

A nonintrusive technique to continuously control random polarization rotations for quantum communications is proposed. It allows an automatic control of the random polarization rotations that photons suffer during their propagation inside standard fibers, without the use of additional classical signals and hardware. The polarization control method is based on a rigorous and efficient estimation of the quantum bit error rate, derived from the Clopper-Pearson confidence interval for a binomial distribution. A system of frames with control and data qubits is employed. The number of control qubits in each frame is optimized in real time in order to minimize the system overhead.