Abstract:

In this presentation, we explore methods of identifying quantum phases in quantum many-body systems using entanglement measures and the Wilson Ratio. Traditional approaches based on Ginzburg-Landau theory often fall short when addressing many quantum phase transitions. We first demonstrate that various quantum phases can be discerned through entanglement measures, such as concurrence. Additionally, we discuss how the Wilson Ratio (WR), a dimensionless parameter, provides a sophisticated characterization of the quantum liquid phase diagram. This is illustrated through examples such as the antiferromagnetic Heisenberg model and the δ-function interacting Fermi gas (Yang-Gaudin model). Employing the thermodynamic Bethe Ansatz (TBA) formalism, we derive universal properties of these models across varying interaction strengths and provide a detailed analysis of the Tomonaga-Luttinger liquid (TLL). In the TLL phase, the WR, which equals 4 times the Luttinger parameter (Ks), remains nearly constant across different temperatures. We propose that both entanglement measures and the Wilson Ratio are effective tools for identifying quantum phase transitions in a broad array of materials.

Biography:

Prof. Hai-Qing Lin obtained his PhD (with Jorge Hirsh) from the University of California, San Diego, in 1987. He then did postdoctoral work at Brookhaven National Laboratory (1987-1989) and Los Alamos National Laboratory (1989-1991). He was a research assistant professor at the University of Illinois at Urbana-Champaign (1991-1995). Then he joined the Chinese University of Hong Kong (1995-2010), moved to the Beijing Computational Science Research Center (2010-2022), and has been at Zhejiang University since 2022. Prof. Lin's research interests span condensed matter theory and computational physics, encompassing strongly correlated electron systems, surface plasmons, materials under high pressure, quantum entanglement and phase transitions, magnetism, superconductivity, many-body physics, and the development of numerical simulation techniques. His contributions to the development and application of computational methods to quantum many-body systems earned him election as an APS fellow in 2003 and as an academician of the Chinese Academy of Sciences in 2019.