  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.
