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Measurement of geometric phase for mixed states using single photon interferometry

Marie Ericsson·Daryl Achilles·Julio T. Barreiro·David Branning·Nicholas A. Peters·Paul G. Kwiat
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Abstract

Geometric phase may enable inherently fault-tolerant quantum computation. However, due to potential decoherence effects, it is important to understand how such phases arise for {\it mixed} input states. We report the first experiment to measure mixed-state geometric phases in optics, using a Mach-Zehnder interferometer, and polarization mixed states that are produced in two different ways: decohering pure states with birefringent elements; and producing a nonmaximally entangled state of two photons and tracing over one of them, a form of remote state preparation.

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Marie Ericsson, Daryl Achilles, Julio T. Barreiro, David Branning, Nicholas A. Peters, Paul G. Kwiat. 2004-12-30. Measurement of geometric phase for mixed states using single photon interferometry. https://doi.org/10.1103/physrevlett.94.050401

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