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- Published: 2018-01-09

*1st Talk*

**Topic:** The stability of the non-abelian topological phase in the Kitaev materials and quantum Hall systems

**Speaker:** Zheng ZHU (MIT)

**Abstract:**

The exotic phases in condensed matters, especially non-abelian topological phase, have spurred a wide variety of investigations in recent years. Typical examples of such phase have been proposed in Kitaev materials around equal coupling and quantum Hall liquid in a half-filled second Landau level. By combining density matrix renormalization group (DMRG) and exact diagonalization (ED), we study the stability of non-Abelian topological spin liquid phase in the two-dimensional (2D) Kitaev honeycomb model subject to a magnetic field, and the quantum Hall liquid in a half-filled second Landau level (n=1) against with band mass anisotropy. In the Kitaev systems, we characterize the topological phase based on the energy spectra, entanglement, topological degeneracy, and expectation values of Wilson loop operators, and more crucially, we find the antiferromagnetic (AFM) Kitaev spin liquid remains robust up to a magnetic field that is an order of magnitude larger than ferromagnetic (FM) one. In the quantum Hall system, We analyze the energy spectrum, guiding center structure factors, and find increasing the mass anisotropy induces a quantum phase transition from the Moore-Read state to a uni-directional quantum Hall stripe, which has a periodicity of a few magnetic lengths and survives in the thermodynamic limit.

*2nd Talk*

**Topic:** AdS/CFT, condensed matter physics, and general relativity

**Speaker:** Jie REN (Hebrew Univ.)

**Abstract:**

Strongly coupled systems without quasiparticles are challenging problems in condensed matter physics. The AdS/CFT correspondence maps a strongly coupled quantum field theory in the large-N limit to a classical gravity described by general relativity, and thus provides useful insights into strongly coupled systems. I will talk about four works. (1) An analytic correlation function near the Fermi surface for non-Fermi liquids. (2) Use of hyperscaling-violating geometries to construct hard-gapped insulators with momentum dissipation. (3) Asymptotically AdS spacetimes with a timelike Kasner singularity. (4) Holographic superconductors that break the translational symmetry spontaneously as a part of the phase diagram of high-temperature superconductors. Asymptotically AdS spacetimes are much richer than asymptotically flat spacetimes, and I will discuss several topics in numerical relativity related to AdS/CFT.

**Time: **14:00pm, Jan. 9 (Tue.), 2018

**Venue:** Rm. S401, Kavli ITS Meeting Room, UCAS Teaching Building [Map]

**地址：**北京市海淀区中关村南一条3号 中国科学院大学教学楼S401会议室