Dynamical Decoupling in Optical Fibers: Preserving Polarization Qubits   from Birefringent Dephasing
  One of the major challenges in quantum computation has been to preserve the coherence of a quantum system against dephasing effects of the environment. The information stored in photon polarization, for example, is quickly lost due to such dephasing, and it is crucial to preserve the input states when one tries to transmit quantum information encoded in the photons through a communication channel. We propose a dynamical decoupling sequence to protect photonic qubits from dephasing by integrating wave plates into optical fiber at prescribed locations. We simulate random birefringent noise along realistic lengths of optical fiber and study preservation of polarization qubits through such fibers enhanced with Carr-Purcell-Meiboom-Gill (CPMG) dynamical decoupling. This technique can maintain photonic qubit coherence at high fidelity, making a step towards achieving scalable and useful quantum communication with photonic qubits. 
Bhaskar Roy Bardhan, Petr M. Anisimov, Manish K. Gupta, Katherine L.   Brown, N. Cody Jones, Hwang Lee, Jonathan P. Dowling
quant-ph