# Dresden 2020 – wissenschaftliches Programm

# Die DPG-Frühjahrstagung in Dresden musste abgesagt werden! Lesen Sie mehr ...

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# TT: Fachverband Tiefe Temperaturen

## TT 22: Quantum Dots, Quantum Wires, Point Contacts

### TT 22.4: Vortrag

### Dienstag, 17. März 2020, 10:15–10:30, HSZ 201

**Transport geometric phases: breaking gauge symmetries** — •Roman-Pascal Riwar^{1} and Janine Splettstoesser^{2} — ^{1}PGI-2, Forschungszentrum Jülich, Germany — ^{2}MC2, Chalmers University of Technology, Sweden

Geometric phases and their relation to topological phase transitions are by now well-established notions in closed quantum systems. The generalization to open quantum systems on the other hand is an actively considered problem. We here review some of our recent works on geometric phases defined in the charge transport statistics of small quantum systems, and explore possible relations. Namely, the geometric phase can either be defined along the time axis (time-dependently driven systems) or along the detector momentum (time-dependent measurements). We find that there are two important gauge degrees of freedom: one related to energy displacement currents, and the other to charge displacement currents. We show for driven quantum systems, that violation of energy conservation renders the geometric phase highly sensitive to whether or not many-body interactions are present in the system. We contrast these findings to time-dependent measurements schemes, where geometric phases along the detector momentum are important. Here, the presence of non-zero displacement currents allows to probe and analyse dynamical phase transitions, and the resulting fractional charges.