Quantum Codes from Constacyclic Codes over Polynomial Residue Rings

Sufficient and necessary conditions for Hermitian (1+λu)-constacyclic self-orthogonal codes over F_p^m+uF_p^m are obtained, where λ is a unit of F_p^m+uF_p^m. Based on this, a new method for the construction of p^m-ary quantum codes from the obtained Hermitian (1+λu)-constacyclic self-orthogonal codes over F_p^m+uF_p^m is given. As an example,p^m-1, p_m-2d+1, d_p^m quantum MDS codes are constructed for 1 ≤ d ≤ (p^m+1)/2 and p≠2, as well as some other quantum codes.