Probing Hybridization of a Single Energy Level Coupled to Superconducting Leads

Abstract

Electron transport through a quantum dot coupled to superconducting leads shows a sharp conductance onset when a quantum dot orbital level crosses the superconducting coherence peak of one lead. We study superconducting single electron transistors in the weak coupling limit by connecting individual gold nanoparticles with aluminum junctions formed by electromigration. We show that the transport features close to the conductance onset threshold can be accurately described by the quantum dot levels' hybridization with the leads, which is strongly enhanced by the divergent density of states at the superconducting gap edge. This highlights the importance of electron cotunneling effects in spectroscopies with superconducting probes.

References in corpus (6)

• Observation of Majorana Fermions in Ferromagnetic Atomic Chains on a Superconductor
• The Kondo effect in C${}_{60}$ single-molecule transistors
• Tunneling processes into localized subgap states in superconductors
• Protection of excited spin states by a superconducting energy gap
• Measurement of discrete energy-level spectra in individual chemically-synthesized gold nanoparticles
• Superconductivity-enhanced bias spectroscopy in carbon nanotube quantum dots

Cited by in corpus (8)

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• Simple Floquet-Wannier-Stark-Andreev viewpoint and emergence of low-energy scales in a voltage-biased three-terminal Josephson junction
• Magnetic-Field-Induced Transition in a Quantum Dot Coupled to a Superconductor
• Recent Developments in Quantum-Circuit Refrigeration
• Landau-Zener-Stueckelberg physics with a singular continuum of states
• Charge dynamics in quantum-circuit refrigeration: thermalization and microwave gain