Conduction channels of superconducting quantum point contacts

Abstract

Atomic quantum point contacts accommodate a small number of conduction channels. Their number N and transmission coefficients {T_n} can be determined by analyzing the subgap structure due to multiple Andreev reflections in the current-voltage (IV) characteristics in the superconducting state. With the help of mechanically controllable break-junctions we have produced Al contacts consisting of a small number of atoms. In the smallest stable contacts, usually three channels contribute to the transport. We show here that the channel ensemble {T_n} of few atom contacts remains unchanged up to temperatures and magnetic fields approaching the critical temperature and the critical field, respectively, giving experimental evidence for the prediction that the conduction channels are the same in the normal and in the superconducting state.

8 pages, 5 .eps figures. To be published in Physica B 223

References in corpus (6)

• Microscopic origin of the conducting channels in metallic atomic-size contacts
• Quantum suppression of shot noise in atom-size metallic contacts
• Evidence for saturation of channel transmission from conductance fluctuations in atomic-size point contacts
• Thermopower of atomic-size metallic contacts
• Theory of AC Josepson Effect in Superconducting Constrictions
• General transport properties of superconducting quantum point contacts: a Green functions approach

Cited by in corpus (5)

• Quantum properties of atomic-sized conductors
• DC-transport in superconducting point contacts: a full counting statistics view
• Superfluid signatures in a dissipative quantum point contact
• Subharmonic gap structure in superconducting scanning tunneling microscope junctions
• Observation of a subharmonic gap singularity in interlayer tunneling characteristics of Bi2Sr2CaCu2O8+d