Salah A. Aly Markus Grassl Andreas Klappenecker Martin Rötteler Pradeep Kiran Sarvepalli Quantum Convolutional BCH Codes http://arxiv.org/abs/quant-ph/0703113 2007 CoRR abs/quant-ph/0703113 db/journals/corr/corr0703.html#abs-quant-ph-0703113 informal publication