Low Temperature Physics: 36, 902 (2010); https://doi.org/10.1063/1.3515521 (9 pages)
Физика Низких Температур: Том 36, Выпуск 10-11 (Октябрь 2010), c. 1128-1137    ( к оглавлению , назад )

Voltage-driven superconducting weak link as a refrigerator for cooling of nanomechanical vibrations

G. Sonne, M.E. Peña-Aza, and R. I. Shekhter

University of Gothenburg, Department of Physics, Göteborg SE-412 96, Sweden
E-mail: gustav.sonne@physics.gu.se

L.Y. Gorelik

Chalmers University of Technology, Department of Applied Physics, Göteborg SE-412 96, Sweden

M. Jonson

University of Gothenburg, Department of Physics,Göteborg SE-412 96, Sweden
Heriot-Watt University, School of Engineering and Physical Sciences, Edinburgh EH14 4AS, Scotland, UK

Konkuk University, School of Physics, Division of Quantum Phases and Devices, Seoul 143-107, Korea

Received March 31, 2010


We consider a new type of cooling mechanism for a suspended nanowire acting as a weak link between two superconductive electrodes. By applying a bias voltage over the system, we show that the system can be viewed as a refrigerator for the nanomechanical vibrations, where energy is continuously transferred from the vibrational degrees of freedom to the extended quasiparticle states in the leads through the periodic modulation of the inter-Andreev level separation. The necessary coupling between the electronic and mechanical degrees of freedom responsible for this energy-transfer can be achieved both with an external magnetic or electrical field, and is shown to lead to an effective cooling of the vibrating nanowire. Using realistic parameters for a suspended nanowire in the form of a metallic carbon nanotube we analyze the evolution of the density matrix and demonstrate the possibility to cool the system down to a stationary vibron population of ~0.1. Furthermore, it is shown that the stationary occupancy of the vibrational modes of the nanowire can be directly probed from the dc current responsible for carrying away the absorbed energy from the vibrating nanowire.

PACS: 73.23.–b Electronic transport in mesoscopic systems;
PACS: 74.45.+c Proximity effects; Andreev reflection; SN and SNS junctions;
PACS: 85.85.+j Micro- and nanoelectromechanical systems (MEMS/NEMS) and devices.

Key words: nanoelectromechanical systems, superconducting weak links, ground state cooling.