Coherent and quasi-free states

Jan Dereziński, Christian Gérard

Sergio A Albeverio, Raphael J. Høegh-Krohn

Chon‐Fai Kam, Wei-Min Zhang, D.H. Feng

Tomohiro Kanda

We consider Bose–Einstein condensation (BEC) on graphs with transient adjacency matrix. We prove the equivalence of BEC and non-factoriality of the quasi-free state. Moreover, quasi-free states exhibiting BEC decompose into generalized coherent states. We review necessary and sufficient conditions that a quasi-free state is faithful, factor, and pure and quasi-free states are quasi-equivalent, including the papers of Araki and Shiraishi [1], Araki [2], and Araki and Yamagami [3]. Using their formats and results, we prove necessary and sufficient conditions that a generalized coherent state is faithful, factor, and pure and generalized coherent states are quasi-equivalent as well.

Shigeru Yamagami

Geometric positions of square roots of coherent states of CCR algebras are investigated along with an explicit formula for transition amplitudes among them, which is a natural extension of our previous results on quasi-free states and will provide a new insight into the quasi-equivalence problem on coherent states.