Volume 88, Number 1, October 2009
|Number of page(s)||5|
|Section||Condensed Matter: Electronic Structure, Electrical, Magnetic and Optical Properties|
|Published online||26 October 2009|
Pairing of Cooper pairs in a Josephson junction network containing an impurity
Dipartimento di Fisica, Università della Calabria and INFN, Gruppo Collegato di Cosenza, Arcavacata di Rende, I-87036, Cosenza, Italy, EU
2 Dipartimento di Fisica, Università di Perugia and INFN, Sezione di Perugia, Via A. Pascoli, I-06123, Perugia, Italy, EU
Accepted: 16 September 2009
We show how to induce pairing of Cooper pairs (and, thus, superconductivity) as a result of local embedding of a quantum impurity in a Josephson network fabricable with conventional junctions. We find that a boundary double sine-Gordon model provides an accurate description of the dc Josephson current patterns, as well as of the stable phases accessible to the network. We point out that tunneling of pairs of Cooper pairs is robust against quantum fluctuations, as a consequence of the time reversal invariance, arising when the central region of the network is pierced by a dimensionless magnetic flux . We find that, for , a stable attractive finite coupling fixed point emerges and point out its relevance for engineering a two-level quantum system with enhanced coherence.
PACS: 74.20.Mn – Nonconventional mechanisms (spin fluctuations, polarons and bipolarons, resonating valence bond model, anyon mechanism, marginal Fermi liquid, Luttinger liquid, etc.) / 74.81.Fa – Josephson junction arrays and wire networks / 75.10.Pq – Spin chain models
© EPLA, 2009
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