Tunneling spectroscopy of a single quantum dot coupled to a superconductor: From Kondo ridge to Andreev bound states

J D Pillet (1) , P. Joyez (1) , Rok Zitko (2) , M F Goffman (1)

1 QUANTRONICS - Quantronics Group
2 IJS - Jozef Stefan Institute [Ljubljana]

We performed tunneling spectroscopy of a carbon nanotube quantum dot (QD) coupled to a metallic reservoir either in the normal or in the superconducting state. We explore how the Kondo resonance, observed when the QD's occupancy is odd and the reservoir is normal, evolves towards Andreev bound states (ABS) in the superconducting state. Within this regime, the ABS spectrum observed is consistent with a quantum phase transition from a singlet to a degenerate magnetic doublet ground state, in quantitative agreement with a single-level Anderson model with superconducting leads.

Domains: Physics [physics]; Mesoscopic Systems and Quantum Hall Effect [cond-mat.mes-hall]; Superconductivity [cond-mat.supr-con]

J D Pillet, P. Joyez, Rok Zitko, M F Goffman. Tunneling spectroscopy of a single quantum dot coupled to a superconductor: From Kondo ridge to Andreev bound states. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2013, 88 (4), pp.45101. ⟨10.1103/PhysRevB.88.045101⟩. ⟨cea-01479207⟩