Instruments and channels in quantum information theory

Abstract

While a positive operator valued measure gives the probabilities in a quantum measurement, an instrument gives both the probabilities and the a posteriori states. By interpreting the instrument as a quantum channel and by using the typical inequalities for the quantum and classical relative entropies, many bounds on the classical information extracted in a quantum measurement, of the type of Holevo's bound, are obtained in a unified manner.

12 pages, revtex4

References in corpus (2)

• Efficient measurements, purification, and bounds on the mutual information
• Entropy and information gain in quantum continual measurements

Cited by in corpus (10)

• Measurement uncertainty relations for discrete observables: Relative entropy formulation
• Tradeoff Relation between Information and Disturbance in Quantum Measurement
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• Measurement uncertainty relations for position and momentum: Relative entropy formulation
• Necessary and Sufficient Conditions on Measurements of Quantum Channels
• Markovian master equations for quantum-classical hybrid systems
• Unraveling-paired dynamical maps can recover the input of quantum channels
• On the unraveling of open quantum dynamics
• Quantum measurements and entropic bounds on information transmission
• Entropic bounds and continual measurements