Majorana bound state in a coupled quantum-dot hybrid-nanowire system

Area of Science:

• Condensed Matter Physics
• Materials Science
• Quantum Computing

Background:

• Hybrid nanowires integrating semiconductor and superconductor materials are promising for realizing Majorana bound states (MBSs).
• Majorana bound states are exotic quasiparticles with potential applications in topological quantum computing.
• Understanding the emergence and properties of MBSs is crucial for advancing quantum information science.

Purpose of the Study:

• To demonstrate the emergence of MBSs from coalescing Andreev bound states (ABSs) in a hybrid InAs nanowire with epitaxial Al.
• To utilize a quantum dot spectrometer to probe the electronic states in the hybrid nanowire.
• To investigate the topological phase transition and the behavior of ABSs under an applied magnetic field.

Main Methods:

• Fabrication of hybrid InAs nanowires with epitaxial Al superconductor.
• Utilized electrostatic gating to tune the nanowire carrier density to a regime with one or a few ABSs.
• Employed a quantum dot at the nanowire's end as a spectrometer to measure ABS and MBS spectra.
• Applied an axial magnetic field to induce a topological phase.

Main Results:

• Observed the emergence of MBSs from coalescing ABSs in the InAs/Al hybrid nanowire system.
• Demonstrated that ABSs move to zero energy and form MBSs in an applied axial magnetic field, indicating a topological phase.
• Detected hybridization between the MBS and the end-dot bound state, consistent with theoretical models.

Conclusions:

• The study successfully demonstrates the creation and detection of MBSs in a hybrid nanowire system.
• The observed spectral features provide valuable parameters for understanding topological superconductivity.
• This work represents a significant step towards the realization of robust topological qubits for quantum computation.