Freiburg 2019 – wissenschaftliches Programm
FM 59.4: Talk
Mittwoch, 25. September 2019, 14:45–15:00, 3043
Practical guide to simple characterization of superconducting quantum dots — •Martin Žonda1, Alžběta Kadlecová2, Vladislav Pokorný2, and Tomáš Novotný2 — 1Albert Ludwig University of Freiburg, Institute of Physics, Freiburg, Germany — 2Department of Condensed Matter Physics, Charles University, Prague, Czech Republic
Quantum dots attached to superconducting leads can be viewed as tunable Josephson junctions. Their qualitative properties, including the point of 0−π impurity quantum phase transition, can be externally controlled by the gate voltage or the superconducting phase difference of the leads. This makes them a promising candidate for future components of superconducting circuit computers. However, quantitative characterization of these devices, which is necessary for their future implementation, often requires broad scans throughout the parameter space of their theoretical models. This turned to be challenging if precise numerical methods, like NRG or QMC, are used. These methods are especially inconvenient for the initial data analysis.
We offer some inexpensive, fast and reliable alternatives to these procedures. We present analytical formuleas which allow for a very good estimation of the position of the 0−π phase boundary in the complementary weakly interacting and strongly correlated (Kondo) regimes. We also suggest an approach for efficient determination of the quantum phase boundary from measured finite-temperature data.
 A. Kadlecová et al., Phys. Rev. B 95, 195114 (2017)
 A. Kadlecová et al., Phys. Rev. Applied 11, 044094 (2019)