Destructive Little-Parks Effect in a Full-Shell Nanowire-Based Transmon

Area of Science:

• Quantum Computing
• Condensed Matter Physics
• Materials Science

Background:

• Investigating hybrid superconductor-semiconductor systems is crucial for advancing quantum technologies.
• Transmon qubits based on nanowires offer unique properties for quantum information processing.

Purpose of the Study:

• To explore the superconducting properties of an aluminum-shell indium arsenide nanowire transmon.
• To investigate the potential for topological superconductivity and coherent qubit operations in this hybrid system.

Main Methods:

• Fabrication of a semiconductor transmon with an epitaxial aluminum shell around an indium arsenide nanowire core.
• Experimental investigation in the low Josephson energy to charging energy (E_{J}/E_{C}) regime.
• Analysis of Little-Parks oscillations and qubit coherence under applied magnetic flux.

Main Results:

• Destructive Little-Parks oscillations observed, exhibiting reentrant superconductivity and a metallic state.
• Topological superconductivity induced in the core by phase winding around the shell.
• Coherent qubit operations demonstrated in both the zeroth and first superconducting lobes.
• Upper bound on Majorana coupling (E_{M}/h < 10 MHz) established, significantly smaller than Josephson coupling (E_{J}/h ~ 4.7 GHz).

Conclusions:

• The hybrid transmon exhibits tunable superconducting states and supports topological superconductivity.
• The observed bounds on Majorana coupling provide critical insights for designing future topological quantum computing architectures.
• Coherent control of the qubit is achievable, highlighting the potential of these hybrid systems.