We present an experimental scheme to measure the full distribution of many-body observables in spin systems, both in and out of equilibrium, using an auxiliary qubit as a probe. We focus on the determination of the magnetization and the kink-number statistics at thermal equilibrium. The corresponding characteristic functions are related to the analytically-continued partition function. Thus, both distributions can be directly extracted from experimental measurements of the coherence of a probe qubit that is coupled to an Ising-type bath, as reported in [X. Peng et al., Phys. Rev. Lett. 114, 010601 (2015)] for the detection of Lee-Yang zeroes.
@article{arxiv.1812.06983,
title = {Probing the Full Distribution of Many-Body Observables by Single-Qubit Interferometry},
author = {Zhenyu Xu and Adolfo del Campo},
journal= {arXiv preprint arXiv:1812.06983},
year = {2019}
}