Topic: Exotic emergences in low-dimensional quantum Ising models
Speaker: Assoc.Prof. Jianda Wu
Coordinates: PCFT C1124, 16:00, Thursday, March 6
Abstract: When the transverse-field Ising chain (TFIC) at its quantum critical point is perturbed by a longitudinal field along Ising spin direction, it emerges as an integrable model containing eight particles with their scattering matrices and mass spectrum organized by the exceptional E8 Lie algebra. If it weakly couples with the other quantum critical Ising chain but without the longitudinal field, then the weak inter-chain coupling can drive the system to emerge as another integrable model with eight particles, organized by the D8(1) Lie algebra. Either way, realizing the quantum criticality of the TFIC is a key step to access the two exotic integrable systems. In my talk, I will explore the quantum criticality of the TFIC and its role in identifying materials hosting TFIC quantum criticality and exotic E8 physics. My journey began with an inelastic neutron scattering experiment on CoNb2O6, sparking my exploration of E8 physics. Despite a ten-year gap, recent THz spectroscopy on the same material reignited my interest, leading us to challenge the E8 paradigm and propose the D8(1) picture. I will discuss why the D8(1) physics provides a comprehensive understanding for the experimental observations. Along the course, we also surprisingly found long-life-time dark particle, a special kind of many-body magnetic excitation, in the integrable system which accommodates the D8(1) physics.