Abstract
Let p be a prime of the form p=mt+1, where integers t >= 1,m >= 2 and Rm=Fp[u]/um-1. Thus, Rm is a finite commutative non-chain ring. For a given unit lambda is an element of Rm, we study lambda -constacyclic codes of length n over Rm. The necessary and sufficient conditions for these codes to contain their Euclidean duals are determined. As an application from dual-containing lambda -constacyclic codes over Rm, for m=2,3,4, we obtain many new quantum codes that improve on the known existing quantum codes.