Open quantum systems theory as the science of identifying a system in its environment

The talk will discuss some recent results on the theory of open quantum systems as well as on closely related quantum thermodynamics. These results, while different in form, have one thing in common: They suggest a new answer to the question what exactly an open quantum system is, how it is identified in its environment.
1. On the example of a particular model [1] we will show that dynamically the system "stands out" from the environment not immediately, but only after some time.
2. We will also discuss at the level of statics how quantum degrees of freedom can be identified to include them in the system. And we will apply [2] this to quantum thermodynamics.
3. Then we will describe how one can "identify a system in the environment" on the basis of covariance of its dynamics with respect to the free one [3].

References

1. A. E. Teretenkov, “Non-perturbative effects in corrections to quantum master equations arising in Bogolubov–van Hove limit”, J. Phys. A, 54:26 (2021), 265302, 24 pp., arXiv: 2008.02820
2. A. E. Teretenkov, “Effective Gibbs State for Averaged Observables”, Entropy, 24:8 (2022), 1144–22, arXiv: 2110.14407
3. A. E. Teretenkov, “Effective Heisenberg equations for quadratic Hamiltonians”, Int. J. Mod. Phys. A, 37:20-21 (2022), 243020, 13 pp., arXiv: 2202.00826