EAQEC codes from two distinct constacyclic codes

Entanglement-assisted quantum error-correcting (EAQEC) codes are a subclass of quantum error correcting codes which use entanglement as a resource. These codes can provide error correction capability higher than the codes derived from the traditional stabilizer formalism. It is possible to construct an EAQEC code from any classical linear code, unlike standard quantum error-correcting codes, which can only be constructed from dual-containing codes. However, the number c of pre-shared maximally entangled states is usually calculated by computer search. In this paper, we first give a new formula of the intersection dimension of two distinct constacyclic codes. Then, using this formula, we obtain a method of computing the number c of pre-shared maximally entangled states. Finally, to enrich the variety of available EAQEC codes, many new EAQEC codes, are constructed to illustrate our results.