Shanghai Jiao Tong University Physics and Astronomy Academic Innovation Forum for Doctoral Students

Session

Quantum Session II

11 Dec 2021, 10:30

Tsung-Dao Lee Institute

27. A new proposal to discern the transverse-field Ising chain universality

Mr Jiahao Yang (Tsung-Dao Lee Institute)

11/12/2021, 10:30

There has been considerable recent progress in identifying candidate materials for the transverse-field Ising chain (TFIC), a paradigmatic model for quantum criticality. Here, we study the local spin dynamical structure factor of different spin components in the quantum disordered region of the TFIC. We show that the low-frequency local dynamics of the spins in the Ising- and transverse-field...

28. $E_{8}$ excitation in quantum critical Ising chain and its experimental observations

Xiao Wang (Tsung-Dao Lee Institute)

11/12/2021, 10:50

The transverse field Ising chain (TFIC) at its quantum critical point (QCP) in the scaling limit turns to be a central charge 1/2 conformal field theory (CFT). In the vicinity of a small longitudinal magnetic field, eight quasiparticles emerge and the whole system can be described by exceptional $E_{8}$ Lie algebra. This excitation essentially arises from weak confinement due to the...

32. 超快激光操控量子材料的电子维度

Dr 绍峰 段

11/12/2021, 11:10

强激光与多体系统相互作用可以诱导非平衡态的新奇物理现象，例如光致超导、光致亚稳态、光激发相干声子模式和光致拓扑缺陷的产生等。激光脉冲泵浦激发固体材料中的电子提供了一种通过非热方式诱导新颖量子态产生的手段，可以在飞秒至皮秒级的时间尺度上操控材料的宏观属性。最近我们的研究发现，利用飞秒激光可以部分翻转三维电荷密度波材料中的周期性晶格扰动，实现瞬时的二维长程有序电子态，这些研究使得激光对量子材料的操控成为当前的研究热点。相应的电子和晶格动力学可以分别由时间分辨角分辨光电子能谱（trARPES）和超快电子衍射（UED）探测。更有趣的是，光诱导的二维电子态的表面有能隙的打开，这可能是光致非平衡态超导的迹象。利用超快激光调制原子的移动是一种实现二维电子态的新方法，并将成为在量子材料中创造新物质相的新方法。

34. FeSe超导体的时间分辨角分辨光电子能谱研究

Yuanyuan Yang

11/12/2021, 11:30

铁基超导体是第二大类高温超导材料，其具备丰富的相图，通过改变压力或者施加磁场的方式可以实现不同量子相之间的转变。向列相相变是铁基超导体中备受关注的话题，即在发生温度变化时，伴随着高温四方相向低温正交相的晶格结构的相变，电子结构会发生面内的对称性破缺。利用时间分辨角分辨光电子能谱（trARPES）技术，可以直接的对铁基超导体中电子向列相的起源以及与超导相之间的关联进行探索，进一步理解铁基超导体中高温超导的配对机制。FeSe是晶格结构最简单的铁基超导体，其超导转变温度Tc~8 K，向列相转变温度Ts~90 K,且并没有伴随着磁结构的相变，为探究纯的电子向列相与超导相之间的关联提供了独一无二平台。本研究利用trARPES对FeSe中具备不同轨道特征的能带，在激光泵浦之下的超快演变过程进行了探测。我们发现在超快激光泵浦作用下，...

35. The vierbein geometric theory for twisted bilayer graphene and rotating bilayer graphene

Jia-Zheng Ma (Sun-Yat sen University)

11/12/2021, 11:50

TBG and moire system have attracted huge interest in both experimantal and theoretical community due to its exotic strong correlated properties and rich phase diagram. However there is still lack of a general theory for arbitrary twisted angle without commensurate approximation. And the superconductive pairing mechanism in TBG is still controversial.
We propose a new kind of geometric theory...