کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
1867156 1530615 2011 5 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Nonequilibrium representative ensembles for isolated quantum systems
موضوعات مرتبط
مهندسی و علوم پایه فیزیک و نجوم فیزیک و نجوم (عمومی)
پیش نمایش صفحه اول مقاله
Nonequilibrium representative ensembles for isolated quantum systems
چکیده انگلیسی

An isolated quantum system is considered, prepared in a nonequilibrium initial state. In order to uniquely define the system dynamics, one has to construct a representative statistical ensemble. From the principle of least action it follows that the role of the evolution generator is played by a grand Hamiltonian, but not merely by its energy part. A theorem is proved expressing the commutators of field operators with operator products through variational derivatives of these products. A consequence of this theorem is the equivalence of the variational equations for field operators with the Heisenberg equations for the latter. A finite quantum system cannot equilibrate in the strict sense. But it can tend to a quasi-stationary state characterized by ergodic averages and the appropriate representative ensemble depending on initial conditions. Microcanonical ensemble, arising in the eigenstate thermalization, is just a particular case of representative ensembles. Quasi-stationary representative ensembles are defined by the principle of minimal information. The latter also implies the minimization of an effective thermodynamic potential.


► The evolution of a nonequilibrium isolated quantum system is considered.
► The grand Hamiltonian is shown to be the evolution generator.
► A theorem is proved connecting operator commutators with variational derivatives.
► Quasi-stationary states are described by representative ensembles.
► These ensembles, generally, depend on initial conditions.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Physics Letters A - Volume 375, Issues 30–31, 18 July 2011, Pages 2797–2801
نویسندگان
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