Seminário do Grupo de Física Estatística - FGE
“Bogoliubov quase-averages: spontaneous symmetry breaking and algebra of fluctuations”
Prof. Valentin A. Zagrebnov Départment de Mathématiques - AMU, Institut de Mathématiques de Marseille, France
Dia: 01 de novembro, quarta-feira, às 14h.
Local: Sala 201, Ala 1, Sala de Seminários.
Abstract:
The paper advocates the Bogoliubov method of quase-averages for quantum systems. First, we elucidate is applications to study the phase transitions with Spontaneous Symmetry Breaking (SSB). To this aim we consider example of Bose-Einstein condensation (BEC) in continuous systems. Our analysis of different type of generalised condensations demonstrates that the only physically reliable quantities are those that defined by Bogoliubov quase-averages. In this connection we also give a solution of the problem posed by Lieb, Seiringer and Yngvason. Second, using the scaled Bogoliubov method of quase-averages and taking the structural quantum phase transition as a basic example, we scrutinise a relation between SSB and the critical quantum fluctuations. Our analysis shows that again the quase-averages give na adequate tool for description of the álgebra of critical quantum fluctuation operators in the both commutative and noncommutative cases.
