首 页机构概况机构设置科研人才队伍合作交流研究生教育博士后图书馆创新文化党群园地院重点实验室彭桓武中心信息公开
  学术活动
  您现在的位置:首页 > 学术活动 > 专题学术报告/Seminar
(Seminar) Two indices Sachdev-Ye-Kitaev model
2018-09-12  【 】【打印】【关闭

CAS Key Laboratory of Theoretical Physics

Institute of Theoretical Physics

 Chinese Academy of Sciences

Seminar

Title

题目

Two indices Sachdev-Ye-Kitaev model

Speaker

报告人

Jinwu Ye

Affiliation

所在单位

首都师范大学和 Mississippi State University

Date

日期

2:30pm, Sep 12, 2018, Wednesday

Venue

地点

Conference Room 322, ITP main building

Abstract

摘要

We study the original Sachdev-Ye (SY) model in its Majorana fermion representation which can be called the two indices Sachdev-Ye-Kitaev (SYK) model. Its advantage over the original SY model in the $ SU(M) $ complex fermion representation is that it need no local constraints, so a $1/M $ expansion can be more easily performed. Its advantage over the 4 indices Sachdev-Ye-Kitaev (SYK) model is that it has only two site indices $ J_{ij} $ instead of four indices $ J_{ijkl} $, so it may fit the bulk string theory better. By performing a $1/M $ expansion at $ N=\infty $, we show that a quantum spin liquid (QSL) state remains stable at a finite $ M $. The $ 1/M $ corrections are exactly marginal, so the system remains conformably invariant at any finite $ M $. The 4-point out of time correlation ( OTOC ) shows quantum chaos neither at $ N=\infty $ at any finite $ M $, nor at $ M=\infty $ at any finite $ N $. By looking at the replica off-diagonal channel, we find there is a quantum spin glass (QSG) instability at an exponentially suppressed temperature in $ M $. We work out a criterion for the two large numbers $ N $ and $ M $ to satisfy so that the QSG instability may be avoided. We speculate that at any finite $ N $, the quantum chaos appears at the order of $ 1/M^{0} $, which is the subleading order in the $ 1/M $ expansion. When the $ 1/N $ quantum fluctuations at any finite $ M $ are considered, from a general reparametrization symmetry breaking point of view, we argue that the effective action should still be described by the Schwarzian one, the OTOC shows maximal quantum chaos. We discuss experimental realizations of the two indices SYK. This work may motivate other works to study the possible new gravity dual of the 2 indices SYK model.

Contact person

所内联系人

Chushun Tian

 

IE6.0浏览器,1024X768分辨率 版权所有 © 中国科学院理论物理研究所
地址:北京市海淀区中关村东路55号 邮政编码:100190
京ICP备05002865号】 京公网安备1101080094号