Nonequilibrium Relaxation of Bose-Einstein Condensates: Real-Time Equations of Motion and Ward Identities
學年 91
學期 1
出版（發表）日期 2002-08-25
作品名稱 Nonequilibrium Relaxation of Bose-Einstein Condensates: Real-Time Equations of Motion and Ward Identities
作品名稱（其他語言）
著者 D. Boyanovsky; S.-Y. Wang; D.-S. Lee; H.-L. Yu; S. M. Alamoudi
單位
出版者
著錄名稱、卷期、頁數 Annals of Physics 300(1), p.1-31
摘要 We present a field-theoretical method to obtain consistently the equations of motion for small amplitude condensate perturbations in a homogeneous Bose-condensed gas directly in real time. It is based on a linear response and combines the Schwinger–Keldysh formulation of nonequilibrium quantum field theory with the Nambu–Gor'kov formalism of quasiparticle excitations in the condensed phase and the tadpole method in quantum field theory. This method leads to causal equations of motion that allow us to study the nonequilibrium evolution as an initial value problem. It also allows us to extract directly the Ward identities, which are a consequence of the underlying gauge symmetry and which in equilibrium lead to the Hugenholtz–Pines theorem. An explicit one-loop calculation of the equations of motion beyond the Hartree–Fock–Bogoliubov approximation reveals that the nonlocal, absorptive contributions to the self-energies corresponding to the Beliaev and Landau damping processes are necessary to fulfill the Ward identities in or out of equilibrium. It is argued that a consistent implementation at low temperatures must be based on the loop expansion, which is shown to fulfill the Ward identities order by order in perturbation theory.
關鍵字
語言 en
ISSN 0003-4916
期刊性質 國外
收錄於 SCI
產學合作
通訊作者
審稿制度 否
國別 NLD
公開徵稿
出版型式 ,電子版,紙本
相關連結

機構典藏連結 ( http://tkuir.lib.tku.edu.tw:8080/dspace/handle/987654321/122308 )