Quantum Dot Parity Effects in Trivial and Topological Josephson Junctions

Area of Science:

• Condensed Matter Physics
• Quantum Information Science
• Superconductivity

Background:

• Josephson junctions with quantum dots can exhibit tunable transmission phase shifts.
• Topological superconductors host exotic quasiparticles with potential applications in quantum computing.
• The interplay between quantum dots and topological superconductors remains an active area of research.

Purpose of the Study:

• To investigate the behavior of a quantum dot in a Josephson junction coupled to topological superconductors.
• To explore the influence of gate voltage and magnetic flux on quantum dot parity and topological transitions.
• To understand the hybridization effects between confined spins and topological zero-energy modes.

Main Methods:

• Utilizing a full-shell hybrid interferometer setup.
• Employing gate voltage to control the quantum dot's parity (even/odd occupation).
• Applying axial magnetic flux to tune the system between trivial and topological superconducting phases.

Main Results:

• Observed enhanced zero-bias conductance in the topological phase for odd parity.
• Measured increased critical current in the topological phase for odd parity.
• These enhancements are attributed to the hybridization of the quantum dot's confined spin with the topological zero-energy modes of the leads.

Conclusions:

• The study demonstrates a novel interaction between quantum dots and topological superconductors.
• Hybridization effects significantly impact the transport properties (conductance, critical current) in the topological regime.
• Findings offer insights into controlling and utilizing topological states for quantum technologies.