Sudden Death of Entanglement induced by Polarization Mode Dispersion
  We study the decoherence of polarization-entangled photon pairs subject to the effects of polarization mode dispersion, the chief polarization decoherence mechanism in optical fibers. We show that fiber propagation reveals an intriguing interplay between the concepts of entanglement sudden death, decoherence-free sub-spaces and non-locality. We define the boundaries in which entanglement-based quantum communications protocols relying on fiber propagation can be applied. 
Cristian Antonelli, Mark Shtaif, and Misha Brodsky
quant-ph