Title:Spin dynamics and dark particles in a weak-coupled quantum Ising ladder with D8(1) spectrum

Speaker: Jianda Wu  Shanghai Tsung-Dao Lee Center

Time:2025-02-26 16：00

Venue: Room W105,  Physics Building

Abstract:When two quantum critical transverse-field Ising chains (TFIC) are weakly coupled, the weak inter-chain coupling can drive the system to emerge as an integrable model with eight particles, organized by the D8(1) Lie algebra . Realizing the quantum criticality of the TFIC is a key step to access the exotic integrable system. In my talk, after first exposing the quantum criticality of the TFIC, I will begin my journey with an inelastic neutron scattering experiment on CoNb₂O₆, which claims observation of evidence of E₈ physics in the material. Despite a ten-year gap, recent THz spectroscopy on the same material reignited our 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. We will discuss how the dark particles are able to be prepared via another exotic soliton excitations in the system, and further propose a thermal activation detection of the lightest dark particle.