  In this paper we present several classes of asymptotically good concatenated
quantum codes and derive lower bounds on the minimum distance and rate of the
codes. We compare these bounds with the best-known bound of
Ashikhmin--Litsyn--Tsfasman and Matsumoto. We also give a polynomial-time
decoding algorithm for the codes that can decode up to one fourth of the lower
bound on the minimum distance of the codes.
