title: Quantum phase transitions exposed by rotating the spins.
abstract: Using the exactly solvable XY spin chain as an example, we consider nonadiabatic variation of the Hamiltonian along an isospectral trajectory. We suggest that quantum phase transitions (QPTs) can be revealed by the nonadiabatic geometric or Aharonov-Anandan phase, accumulated in a cycle of the state that starts from a particular initial state. On the other hand, starting as the ground state of the instantaneous Hamiltonian, the state does not return to the initial state if the variation of the Hamiltonian is not adiabatic, but the survival probability can indicate QPTs and display revival phenomena.
authors: Department of Physics & State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, China and Faculty of Science, Kunming University of Science and Technology, Kunming 650093, China.
authors: Xin
authors: X
authors: Li
authors: Department of Physics & State Key Laboratory of Surface Physics, Fudan University, Shanghai 200433, China and Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China.
authors: Yu
authors: Y
authors: Shi