Standard thermometry employs the thermalisation of a probe with the system of interest. This approach can be extended by incorporating the possibility of using the non-equilibrium states of the probe, and the presence of coherence. Here, we illustrate how these concepts apply to the single-qubit thermometer introduced by Jevtic et al. by performing a simulation of the qubit-environment interaction in a linear-optical device. We discuss the role of the coherence, and how this affects the usefulness of non-equilibrium conditions. The origin of the observed behaviour is traced back to the propensity to thermalisation, as captured by the Helmholtz free energy.
@article{arxiv.1609.01590,
title = {Quantum Simulation of single-qubit thermometry using linear optics},
author = {Luca Mancino and Marco Sbroscia and Ilaria Gianani and Emanuele Roccia and Marco Barbieri},
journal= {arXiv preprint arXiv:1609.01590},
year = {2017}
}