Tunneling of Cooper pairs across voltage-biased asymmetric single-Cooper-pair transistors

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Journal Title
Journal ISSN
Volume Title
School of Science | A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2006
Major/Subject
Mcode
Degree programme
Language
en
Pages
054504/1-9
Series
Physical Review B, Volume 74, Issue 5
Abstract
We analyze tunneling of Cooper pairs across voltage biased asymmetric single-Cooper-pair transistors. Also tunneling of Cooper pairs across two capacitively coupled Cooper-pair boxes is considered, when the capacitive coupling and Cooper pair tunneling are provided by a small Josephson junction between the islands. The theoretical analysis is done at subgap voltages, where the current-voltage characteristics depend strongly on the macroscopic eigenstates of the island(s) and their coupling to the dissipative environment. As the environment we use an impedance which satisfies Re[Z(ω)]⪡RQ and a few LC oscillators in series with Z(ω). The numerically calculated I−V curves are compared with experiments where the quantum states of mesoscopic SQUIDs are probed with inelastic Cooper pair tunneling. The main features of the observed I−V data are reproduced. Especially, we find traces of band structure in the higher excited states of the Cooper-pair boxes as well as traces of multiphoton processes between two Cooper-pair boxes in the regime of large Josephson coupling EJ⪢EC.
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Keywords
Cooper pair tunneling, transistors
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Citation
Leppäkangas, J. & Thuneberg, E. & Lindell, R. & Hakonen, Pertti J. 2006. Tunneling of Cooper pairs across voltage-biased asymmetric single-Cooper-pair transistors. Physical Review B. Volume 74, Issue 5. 054504/1-9. ISSN 1098-0121 (printed). DOI: 10.1103/physrevb.74.054504