Abstract
Non-equilibrium states of quantum systems in contact with thermal baths help telling environments with different temperatures or different statistics apart. We extend these studies to a more generic problem that consists in discriminating between two baths with disparate constituents at unequal temperatures. Notably there exist temperature regimes in which the presence of coherence in the initial state preparation is beneficial for the discrimination capability. We also find that non-equilibrium states are not universally optimal, and detail the conditions in which it becomes convenient to wait for complete thermalisation of the probe. These concepts are illustrated in a linear optical simulation.
Highlights
The reduced dynamics of a quantum system interacting with an external environment is typically insensitive to many characteristic features of the latter [1–3]
We find that nonequilibrium states are not universally optimal and detail the conditions in which it becomes advantageous to wait for complete thermalization of the probe
This approach reveals how different properties of the bath affect the nature of the optimal discrimination procedures
Summary
The reduced dynamics of a quantum system interacting with an external environment is typically insensitive to many characteristic features of the latter [1–3]. The minimization of the Helstrom probability of error [23] enables us to confirm that for the generalized statistics tagging scenario we address here, optimal discrimination performances are obtained by monitoring the probe at times where it is in a nonequilibrium configuration. In this case it turns out that such a result strongly relies on the possibility of exploiting coherence in the input states of A. Component of the Bloch vector decays with a characteristic time scale 1/γq, while the one associated with the other two components is twice as long (see, e.g., Ref. [3], p. 149)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
