We numerically analyze the dynamic behavior of Bose–Einstein condensate(BEC)in a one-dimensional disordered potential before it completely loses spatial quantum coherence.We find that both the disorder statistics and...We numerically analyze the dynamic behavior of Bose–Einstein condensate(BEC)in a one-dimensional disordered potential before it completely loses spatial quantum coherence.We find that both the disorder statistics and the atom interactions produce remarkable effects on localization.We also find that the single phase of the initial condensate is broken into many small pieces while the system approaches localization,showing a counter-intuitive step-wise phase but not a thoroughly randomized phase.Although the condensates as a whole show less flow and expansion,the currents between adjacent phase steps retain strong time dependence.Thus we show explicitly that the localization of a finite size Bose–Einstein condensate is a dynamic equilibrium state.展开更多
Non-classical paired photons are generated by a four-wave mixing process in a far-detuning three-level system with cold atoms.A violation of the Cauchy–Schwartz inequality of a factor of 310 is observed.This phenomen...Non-classical paired photons are generated by a four-wave mixing process in a far-detuning three-level system with cold atoms.A violation of the Cauchy–Schwartz inequality of a factor of 310 is observed.This phenomenon shows that paired photons have a non-classical correlation.The experimental results are compared with theoretical results obtained using perturbation theory.The oscillation frequencies of the two-photon intensity correlation functions are in reasonable agreement with the effective Rabi frequencies of the coupling laser.However,we find that the dephasing rates(or decay rates)observed are far larger than the theoretical values.展开更多
基金Supported by the National Natural Science Foundation of China under Grant No.10974211the National Basic Research Program of China under Grant No.2011CB921504the Research Project of Shanghai Science and Technology Commission under Grant Nos.09DJ1400700 and 10DJ1400600.
文摘We numerically analyze the dynamic behavior of Bose–Einstein condensate(BEC)in a one-dimensional disordered potential before it completely loses spatial quantum coherence.We find that both the disorder statistics and the atom interactions produce remarkable effects on localization.We also find that the single phase of the initial condensate is broken into many small pieces while the system approaches localization,showing a counter-intuitive step-wise phase but not a thoroughly randomized phase.Although the condensates as a whole show less flow and expansion,the currents between adjacent phase steps retain strong time dependence.Thus we show explicitly that the localization of a finite size Bose–Einstein condensate is a dynamic equilibrium state.
基金by the National Natural Science Foundation of China under Grant No 10804115the National Basic Research Program of China under Grant Nos 2006CB921202 and 2011CB921504+1 种基金the Knowledge Innovation Project of Chinese Academy of Sciencesthe Shanghai Committee of Science and Technology under Grant No 09DJ1400700.
文摘Non-classical paired photons are generated by a four-wave mixing process in a far-detuning three-level system with cold atoms.A violation of the Cauchy–Schwartz inequality of a factor of 310 is observed.This phenomenon shows that paired photons have a non-classical correlation.The experimental results are compared with theoretical results obtained using perturbation theory.The oscillation frequencies of the two-photon intensity correlation functions are in reasonable agreement with the effective Rabi frequencies of the coupling laser.However,we find that the dephasing rates(or decay rates)observed are far larger than the theoretical values.
