Ballistic Majorana nanowire devices.

Area of Science:

• Condensed Matter Physics
• Topological Superconductivity
• Quantum Computing

Background:

• Majorana modes are exotic zero-energy excitations in topological superconductors, crucial for non-Abelian statistics and fault-tolerant quantum computing.
• Previous experimental efforts to detect Majorana modes have been significantly hampered by material disorder, which can obscure or mimic their characteristic signatures.
• Semiconductor nanowires coupled to superconductors are a leading platform for realizing and detecting Majorana modes.

Purpose of the Study:

• To demonstrate robust signatures of Majorana modes in a low-disorder semiconductor nanowire system.
• To overcome the limitations imposed by disorder in previous Majorana detection experiments.
• To provide experimental evidence for topologically distinct phases in a ballistic nanowire system.

Main Methods:

• Fabrication and characterization of indium antimonide (InSb) nanowire devices with high-quality interfaces and ballistic transport properties.
• Application of external magnetic fields and local electrostatic gating to control carrier density and induce topological superconductivity.
• Measurement of zero-bias conductance peaks as a signature of Majorana modes under varying chemical potential, Zeeman energy, and tunnel barrier conditions.

Main Results:

• Observed a robust zero-bias peak, a key signature of Majorana modes, in InSb nanowires exhibiting ballistic transport.
• The zero-bias peak remained stable over a wide parameter range, indicating its topological origin and insensitivity to experimental fluctuations.
• Resolved distinct parameter regions with and without the zero-bias peak, clearly indicating the presence of topologically distinct phases and excluding disorder-induced artifacts.

Conclusions:

• The experimental results provide strong evidence for the existence of Majorana modes in a low-disorder, ballistic InSb nanowire system.
• The observed signatures are consistent with theoretical predictions for Majorana modes in topological superconductors and rule out alternative explanations related to disorder.
• This work represents a significant advancement in the experimental realization of Majorana modes, crucial for the development of topological quantum computing.