Quantum Simulation of single-qubit thermometry using linear optics
  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. 
Luca Mancino, Marco Sbroscia, Ilaria Gianani, Emanuele Roccia, Marco   Barbieri
quant-ph