Abstract
Protective measurement, which was proposed as a method of observing the wavefunction of a single system, is extended to the observation of the density matrix of a single system. This provides a new meaning to the density matrix as having the same ontological status as the wave function describing a pure state. This also enables quantum entropy to be associated with a single system.
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Y. Aharonov, J. Anandan, and L. Vaidman, Phys. Rev. A 47, 4616 (1993). Y. Aharonov and L. Vaidman, Phys. Lett. A 178, 38 (1993).
J. Anandan, Found. Phys. Lett. 6, 503 (1993).
Jeeva Anandan and Katherine Brading, “The ontological status of density matrices,” in preparation.
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Anandan, J., Aharonov, Y. Meaning of the Density Matrix. Found Phys Lett 12, 571–578 (1999). https://doi.org/10.1023/A:1021699226154
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DOI: https://doi.org/10.1023/A:1021699226154