Many-body effects in quantum metrology
Abstract
We study the impact of many-body effects on the fundamental precision limits in quantum metrology. On the one hand such effects may lead to non-linear Hamiltonians, studied in the field of non-linear quantum metrology, while on the other hand they may result in decoherence processes that cannot be described using single-body noise models. We provide a general reasoning that allows to predict the fundamental scaling of precision in such models as a function of the number of atoms present in the system. Moreover, we describe a computationally efficient approach that allows for a simple derivation of quantitative bounds. We illustrate these general considerations by a detailed analysis of fundamental precision bounds in a paradigmatic atomic interferometry experiment with standard linear Hamiltonian but with both single and two-body losses taken into account---a model which is motivated by the most recent Bose-Einstein Condensate (BEC) magnetometry experiments. Using this example we also highlight the impact of the atom number super-selection rule on the possibility of protecting interferometric protocols against decoherence.
Cite
@article{arxiv.1810.03651,
title = {Many-body effects in quantum metrology},
author = {Jan Czajkowski and Krzysztof Pawłowski and Rafał Demkowicz-Dobrzański},
journal= {arXiv preprint arXiv:1810.03651},
year = {2019}
}