We show that a conical magnetic field can be used to tune the  topological order and hence anyon excitations of the Z2 quantum spin  liquid in the isotropic antiferromagnetic Kitaev model. A novel topological order, featured with Chern number C=4 and Abelian anyon  excitations, is induced in a narrow range of intermediate fields Hc1  <= H <= Hc2. On the other hand, the C=1 Ising-topological order  with non-Abelian anyon excitations, is previously known to be present  at small fields, and interestingly, is found here to survive up to  Hc1, and revive above Hc2, until the system becomes trivial above a  higher field Hc3. The results are obtained by devoloping and applying  a Z2 mean field theory, that works at finite fields and is  asymptotically exact in the zero field limit, and the associated  variational quantum Monte Carlo. Evidences against a U1 spin liquid in  the intermediate field regime are also discussed.

About the speaker:
王强华教授，1985-1989年在南京大学少年部(后称基础教育强化部)本科学习，获理学学士学位。1989-1993年在南京大学物理系硕博连读，获理学博士学位，并留校工作。1995-1997年在香港大学做博士后研究工作。2000-2002年在加州大学伯克利分校做访问研究。1993-1995年任南京大学物理系讲师，1995-2002年任副教授，2002-今任教授。2004年获国家杰出青年基金以及教育部霍英东研究基金资助,2006年获教育部长江学者特聘教授。研究领域：强关联电子系统的超导机理与物理性质，泛函重整化群、密度矩阵重整化群及量子蒙特卡洛等数值计算，拓扑绝缘体与拓扑超导体。