Quantum Computation and Information Seminar 

07/11/2008, 15:00 — 16:00 — Room P4.35, Mathematics Building
Shi-Jian Gu, Chinese University of Hong-Kong

Fidelity susceptibility and quantum phase transitions

Quantum phase transitions of a many-body system at zero temperature are characterized by the change of the ground state properties as model parameter g in the system Hamiltonian H(g) is varied across the transition point gc. This primary observation motivates people to explore the role of fidelity, a concept emerging from quantum information theory, in critical phenomena. Since the fidelity measures the similarity between states, the change of the ground state structure around the quantum critical point should result in a dramatic change in the fidelity across the critical point. In this talk, we will introduce the role of leading term in the fidelity, i.e. the fidelity susceptibility, in the quantum phase transitions occurred in several strongly correlated systems, such as the one-dimensional asymmetric Hubbard model, the Kitaev honeycomb model, etc. We argue that the fidelity susceptibility can be used to describe the critical phenomena in its own way.