Nonlocal supercurrent of quartets in a three-terminal Josephson junction

Area of Science:

• Condensed Matter Physics
• Quantum Electronics
• Superconductivity

Background:

• Traditional Josephson junctions exhibit equilibrium-dependent Andreev bound states (ABS).
• Nonlocal phenomena in superconducting systems are of significant research interest.
• Understanding electron correlations is crucial for advancing quantum technologies.

Purpose of the Study:

• To experimentally demonstrate a novel nonlocal supercurrent carried by electron quartets.
• To investigate the properties of Andreev bound states (ABS) in a three-terminal Josephson junction.
• To confirm the existence of a quartet supercurrent persisting in the nonlinear regime.

Main Methods:

• Fabrication of a highly coherent three-terminal Josephson junction using InAs nanowire and aluminum superconductor.
• Nonlocal conductance measurements to probe charge transport.
• Cross-correlation measurements of current fluctuations to identify unique signatures.

Main Results:

• Observation of a resonance indicative of a quartet supercurrent in the nonlinear regime.
• Distinctive signatures of the quartet supercurrent confirmed through current fluctuation analysis.
• Experimental data ruled out competing mechanisms, supporting the quartet supercurrent hypothesis.

Conclusions:

• The study provides the first experimental evidence of a novel nonlocal quartet supercurrent.
• The observed quartet supercurrent is mediated by a nonlocal Andreev bound state (ABS) persistent in the nonlinear regime.
• This finding opens new avenues for exploring exotic quantum phenomena and designing advanced superconducting devices.