Quantum criticality as a resource for quantum estimation
Abstract
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 \lambda 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 \lambda at 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).
Cite
@article{arxiv.0708.1089,
title = {Quantum criticality as a resource for quantum estimation},
author = {Paolo Zanardi and Matteo G A Paris and Lorenzo Campos Venuti},
journal= {arXiv preprint arXiv:0708.1089},
year = {2009}
}
Comments
7 pages. Revised and extended version. Gained one author and a specific example