# Dresden 2020 – wissenschaftliches Programm

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# HL: Fachverband Halbleiterphysik

## HL 79: Quantum dots and wires IV

### HL 79.7: Vortrag

### Freitag, 20. März 2020, 11:15–11:30, POT 151

**Least biased steady state of open quantum systems** — •Boris Melcher, Boris Gulyak, and Jan Wiersig — Institut für Physik, Otto-von-Guericke-Universität Magdeburg, Postfach 4120, D-39016 Magdeburg, Germany

By applying the principle of maximum entropy [1] we develop a stand-alone approach to conclude a reasonable guess for the full density matrix of an open quantum system in a steady state. It is centered around the obvious perception that in the steady state all observables are constant in time. This is used as a constraint to deduce the least biased density matrix self-consistently.

In doing so, we circumvent the many-particle hierarchy problem that arises in conventional equation of motion techniques [2]. Furthermore, our approach gives access to the full density matrix and thus all relevant expectation values and correlation functions as well as the full statistics of the investigated system.

We employ the maximum entropy method for quantum dot microcavity lasers and demonstrate excellent agreement with conventional approaches [3]. Beyond that, we study the systems in terms of entropy, mean photon number, autocorrelation functions as well as the full photon statistics, giving insight into the fundamental physical processes operating in these systems.

[1] E. T. Jaynes, Phys. Rev. 106, 620 (1957), 108, 171 (1957)

[2] H. A. M. Leymann et al., Phys. Rev. B 89, 085308 (2014)

[3] B. Melcher et al., Phys. Rev. A 100, 013854 (2019)