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Kinematic approach to off-diagonal geometric phases of nondegenerate and degenerate mixed states

D. M. Tong·Erik Sjöqvist·Stefan Filipp·L. C. Kwek·C. H. Oh
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Abstract

Off-diagonal geometric phases have been developed in order to provide information of the geometry of paths that connect noninterfering quantal states. We propose a kinematic approach to off-diagonal geometric phases for pure and mixed states. We further extend the mixed state concept proposed in [Phys. Rev. Lett. {\bf 90}, 050403 (2003)] to degenerate density operators. The first and second order off-diagonal geometric phases are analyzed for unitarily evolving pairs of pseudopure states.

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D. M. Tong, Erik Sjöqvist, Stefan Filipp, L. C. Kwek, C. H. Oh. 2004-05-11. Kinematic approach to off-diagonal geometric phases of nondegenerate and degenerate mixed states. https://doi.org/10.1103/physreva.71.032106

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