Meaning of the density matrix

J. Anandan*, Y. Aharonov

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish
Pages (from-to)571-578
Number of pages8
JournalFoundations of Physics Letters
Issue number6
StatePublished - Dec 1999


FundersFunder number
Israel National Academy of Sciences61495
National Science FoundationPHY-9601280


    • Density matrix
    • Entropy
    • Quantum measurement


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