__物理系学术报告____ Physics Department Seminar__

**11**月**2**日**16:00-17:00**，教**12-504**

Fidelity
susceptibility, quantum adiabatic condition, and quantum phase transitions

顾世建 教授

香港中文大学物理系

摘 要

In this talk, I will firstly
introduce the quantum fidelity approach to quantum phase transitions based on
its leading term, i.e. the fidelity susceptibility. The fidelity susceptibility
denotes the adiabatic leading response of the ground state to the driving
parameter. Differ from traditionally approach based on the ground-state energy,
the fidelity susceptibility shows distinct scaling and singular behaviours around the critical point.

Secondly, I would like to introduce
the relation between the fidelity susceptibility and quantum adiabatic theorem.
For a d-dimensional quantum many-body system, we show that the duration time
required by its ground-state adiabatic process does not depend on the
microscopic details, but the quantum adiabatic dimension, which for instance in
the gapless region, depends on global properties like dimensionality, the
dynamic exponent, and the scaling dimension of the driving Hamiltonian. The
quantum adiabatic theorem might be violated in case that the quantum adiabatic
dimension is larger than the system's real dimension.