Quantum cyclic and constacyclic codes

Based on classical quaternary constacyclic linear codes, we construct a set of quantum codes with parameters [[(4^m -1)/3, (4^m -1)/3 -2(3l + b)m, 4l + b + 2]] where m≥4, 1≤b≤3, and 12l + 3b < 2 × 4^└<span>(m+2)/3┘/-1, which are better than the codes in Bierbrauer and Edel (2000).