We address quantum critical systems as a resource in quantum estimation and derive the ultimate quantum limits to the precision of any estimator of the coupling parameters. In particular, if L denotes the size of a system and λ is the relevant coupling parameters driving a quantum phase transition, we show that a precision improvement of order 1/L may be achieved in the estimation of λ at the critical point compared to the noncritical case. We show that analog results hold for temperature estimation in classical phase transitions. Results are illustrated by means of a specific example involving a fermion tight-binding model with pair creation (BCS model). © 2008 The American Physical Society.
CITATION STYLE
Zanardi, P., Paris, M. G. A., & Campos Venuti, L. (2008). Quantum criticality as a resource for quantum estimation. Physical Review A - Atomic, Molecular, and Optical Physics, 78(4). https://doi.org/10.1103/PhysRevA.78.042105
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