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Full-Text Articles in Quantum Physics
Conditional Density Operators And The Subjectivity Of Quantum Operations, Matthew S. Leifer
Conditional Density Operators And The Subjectivity Of Quantum Operations, Matthew S. Leifer
Mathematics, Physics, and Computer Science Faculty Articles and Research
Assuming that quantum states, including pure states, represent subjective degrees of belief rather than objective properties of systems, the question of what other elements of the quantum formalism must also be taken as subjective is addressed. In particular, we ask this of the dynamical aspects of the formalism, such as Hamiltonians and unitary operators. Whilst some operations, such as the update maps corresponding to a complete projective measurement, must be subjective, the situation is not so clear in other cases. Here, it is argued that all trace preserving completely positive maps, including unitary operators, should be regarded as subjective, in …