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Flux-Controlled Two-Site Kitaev Chain
Ivan Kulesh1, Sebastiaan L D Ten Haaf1, Qingzhen Wang1
1QuTech and Kavli Institute of Nanoscience, Delft University of Technology, Delft, 2600 GA, The Netherlands.
Physical Review Letters
|August 18, 2025
Summary
Researchers engineered Majorana bound states (MBSs) in quantum dots using tunable Josephson junctions. Controlling Andreev bound states (ABSs) with electrostatic and phase methods expands the parameter space for MBSs and probes their spatial distribution.
Area of Science:
- Condensed matter physics
- Quantum information science
- Nanotechnology
Background:
- Artificial Kitaev chains are realized in semiconducting-superconducting hybrid devices.
- Andreev bound states (ABSs) mediate coupling between quantum dots in these systems.
- Engineering Majorana bound states (MBSs) requires precise control over ABS energies.
Purpose of the Study:
- To demonstrate control over coupling between distant quantum dots using extended ABSs.
- To investigate the role of electrostatic and phase control in expanding the parameter space for MBSs.
- To gain insights into the spatial distribution of Majorana wave functions.
Main Methods:
- Utilizing flux-tunable Josephson junctions to engineer extended ABSs.
- Applying electrostatic and phase control mechanisms to manipulate ABS energies.
- Employing a spectroscopic probe in the hybrid region between quantum dots.
Main Results:
- Extended ABSs in Josephson junctions effectively control coupling between quantum dots separated by approximately 1 μm.
- Combined electrostatic and phase control significantly increases the parameter space for observing MBSs.
- Spectroscopic probing provides information on the spatial distribution of the Majorana wave function.
Conclusions:
- Flux-tunable Josephson junctions offer a viable platform for controlling quantum dot coupling via ABSs.
- Enhanced control over ABSs is crucial for advancing the realization of MBSs in artificial Kitaev chains.
- This work provides a method for probing Majorana wave function localization in multi-site systems.
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