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Geometric phases for mixed states in interferometry

Erik Sjöqvist·Arun K. Pati·Artur Ekert·Jeeva S. Anandan·Marie Ericsson·Daniel K. L. Oi·Vlatko Vedral
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Abstract

We provide a physical prescription based on interferometry for introducing the total phase of a mixed state undergoing unitary evolution, which has been an elusive concept in the past. We define the parallel transport condition that provides a connection-form for obtaining the geometric phase for mixed states. The expression for the geometric phase for mixed state reduces to well known formulas in the pure state case when a system undergoes noncyclic and unitary quantum evolution.

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Erik Sjöqvist, Arun K. Pati, Artur Ekert, Jeeva S. Anandan, Marie Ericsson, Daniel K. L. Oi, Vlatko Vedral. 2000-06-22. Geometric phases for mixed states in interferometry. https://doi.org/10.1103/physrevlett.85.2845

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