We study the effects of external magnetic fields on the precision of parameter estimation with thermal entanglement of two spins in XX model, in the presence of Dzyaloshinskii-Moriya (DM) interaction. Calculating the quantum Fisher information, we show that homogeneous magnetic field B, inhomogeneous magnetic field b or DM interaction D increases the precision of parameter estimation, overwhelming the destructive effects of thermalization. We also show that for the model in consideration, the effects of b and D are the same. However, the existence of both b and B (or both D and B) decreases the precision. We find that in order to increase the precision in parameter estimation tasks, applying b in the ferromagnetic case and B in the antiferromagnetic case should be preferred.
@article{arxiv.1602.04168,
title = {Parameter Estimation with Dzyaloshinskii-Moriya Interaction under External Magnetic Fields},
author = {Fatih Ozaydin and Azmi Ali Altintas},
journal= {arXiv preprint arXiv:1602.04168},
year = {2016}
}