Zheng Qiang, Wang Wen-ge, Qin Pinquan, Wang Ping, Zhang Xiaoping, Ren Zhongzhou
Department of Physics, Nanjing University, Nanjing 210093, China.
Phys Rev E Stat Nonlin Soft Matter Phys. 2009 Jul;80(1 Pt 2):016214. doi: 10.1103/PhysRevE.80.016214. Epub 2009 Jul 30.
We study the quantum Loschmidt echo (LE) in a Bose-Einstein condensate (BEC) in a double-well potential. The BEC may undergo a dynamical phase transition between two phases: a tunneling phase and a self-trapping phase. For sufficiently weak perturbation, the LE has Gaussian decay in both phases. While, for relatively strong perturbation, the LE has a Gaussian decay in the self-trapping phase and has a stretched exponential decay in the tunneling phase. This qualitative difference in the decaying law of the LE in the two phases provides a characterization of the dynamical phase transition of the BEC. The semiclassical theory is used to explain the numerically observed behaviors of the LE decay.
