2007/08/31 by Paolo Zanardi, Matteo G A Paris, Lorenzo Campos Venuti · 3 citations
Physics and Astronomy · #quant-ph
paper · pdf · doi:10.1103/physreva.78.042105
published as Phys Rev A vol 78, 042105 (2008) · 7 pages. Revised and extended version. Gained one author and a specific example
arxiv created 2008/08/01 · arxiv updated 2009/12/01
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 λis 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 λat the critical point compared to the non-critical case. We show that analogue 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).