In experiments with superconducting quantum circuits, characterizing the photon statistics of propagating microwave fields is a fundamental task. We quantify the n2+n photon number variance of thermal microwave photons emitted from a black-body radiator for mean photon numbers 0.05≲n≲1.5. We probe the fields using either correlation measurements or a transmon qubit coupled to a microwave resonator. Our experiments provide a precise quantitative characterization of weak microwave states and information on the noise emitted by a Josephson parametric amplifier.
@article{arxiv.1609.07353,
title = {Photon Statistics of Propagating Thermal Microwaves},
author = {J. Goetz and S. Pogorzalek and F. Deppe and K. G. Fedorov and P. Eder and M. Fischer and F. Wulschner and E. Xie and A. Marx and R. Gross},
journal= {arXiv preprint arXiv:1609.07353},
year = {2017}
}