符方伟教授学术报告
报告题目：Two new classes of quantum MDS codes
报 告 人：符方伟教授（南开大学陈省身数学研究所）
报告时间：2018年11月4号(周日)上午9:00-10:00
报告地点：磬苑校区数学科学学院H306
报告摘要：Quantum maximum-distance-separable (MDS) codes are an important class of quantum error-correcting codes. In this talk, we will construct two new classes of quantum MDS codes by employing classical generalized Reed-Solomon (GRS for short) codes and extended GRS codes over finite fields. Our quantum MDS codes have flexible parameters, and most of them have minimum distances larger than q/2+1, where q is the alphabet size. Furthermore, it turns out that our constructions generalize and improve some previous results.
曹永林教授学术报告
报告题目：Construction and enumeration for self-dual cyclic codes over Z_4 of oddly even length
报 告 人：曹永林教授（山东理工大学）
报告时间：2018年11月4号(周日)上午10:00-11:00
报告地点：磬苑校区数学科学学院H306
报告摘要：For any positive odd integer n, a precise representation for cyclic codes over Z_4 of length 2n is given in termsof the Chinese Remainder Theorem. Using this representation, an efficient encoder for each of these codes is described.Then the dual codes are determined precisely and this is used to study codes which are self-dual. In particular, the number of self-dual cyclic codes over Z_4 of length 2n can be calculated from 2-cyclotomic cosets modulon directly. Moreover, mistakesin [Discrete Applied Mathematics 128(2003), 27--46] and [Designs, Codes and Cryptography 39 (2006), 127--153] are corrected.As an application, all 315 self-dual cyclic codes over Z_4of length 30 are listed. Among these codes, there are some new cyclic and self-dual Z_4-codesC with parameters (30,|C|=2^{30},d_H=6,d_L=12) and (30,|C|=2^{30},d_H=5,d_L=10). From these codes and applying the Gray map from Z_4 onto F_2^2, formally self-dual and 2-quasicyclic binary codes with basic parameters[60, 30, 12] and [60, 30, 10] are derived respectively.
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科学技术处
2018年11月2日