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Tunable effective length of fractional Josephson junctions
Daniel Frombach1, Patrik Recher1,2
1Institut für Mathematische Physik, Technische Universität Braunschweig, D-38106 Braunschweig, Germany.
Summary
Topological Josephson junctions (TJJs) can host Majorana zero modes. This study proposes a method to effectively lengthen short TJJs, enabling critical current measurements in more experimental setups.
Area of Science:
- Condensed Matter Physics
- Quantum Information Science
Background:
- Topological Josephson junctions (TJJs) are of significant interest for hosting Majorana zero modes.
- In long junctions, TJJs exhibit distinct critical current features, but realizing these in short junctions is challenging.
Purpose of the Study:
- To propose a method for effectively increasing the junction length of TJJs.
- To enable critical current measurements in short TJJs by coupling them to additional channels or quantum dots.
Main Methods:
- Analytical treatment of effective low-energy models.
- Numerical investigation of Kane-Mele models with edge passivation using tight-binding models.
- Calculation of critical current via Andreev bound state spectrum.
Main Results:
- Demonstrated that coupling to additional channels or quantum dots tunes the effective junction length.
- Showed that critical current in effectively long junctions differs based on perturbation strength (parity changing).
- Provided a pathway for experimental realization in short junctions.
Conclusions:
- The proposed method allows for tunable control over the effective length of TJJs.
- This work facilitates the study of Majorana zero modes in more accessible short junction geometries.
- Understanding the impact of quasiparticle poisoning on critical current is crucial for TJJ characterization.
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