We show that, for pertinent values of the fabrication and control parameters, an attractive finite coupling fixed point emerges in the phase diagram of a Y -junction of superconducting Josephson chains. The new fixed point arises only when the dimensionless flux f piercing the central loop of the network equals π and, thus, does not break time-reversal invariance; for f = π, only the strongly coupled fixed point survives as a stable attractive fixed point. Phase slips (instantons) have a crucial role in establishing this transition: we show indeed that, at f = π, a new set of instantons—the W-instantons—comes into play to destabilize the strongly coupled fixed point. Finally, we provide a detailed account of the Josephson current–phase relationship along the arms of the network, near each one of the allowed fixed points. Our results evidence remarkable similarities between the phase diagram accessible to a Y -junction of superconducting Josephson chains and the one found in the analysis of quantum Brownian motion on frustrated planar lattices.

Y-junction of superconducting Josephson chains

GIULIANO, Domenico;
2009

Abstract

We show that, for pertinent values of the fabrication and control parameters, an attractive finite coupling fixed point emerges in the phase diagram of a Y -junction of superconducting Josephson chains. The new fixed point arises only when the dimensionless flux f piercing the central loop of the network equals π and, thus, does not break time-reversal invariance; for f = π, only the strongly coupled fixed point survives as a stable attractive fixed point. Phase slips (instantons) have a crucial role in establishing this transition: we show indeed that, at f = π, a new set of instantons—the W-instantons—comes into play to destabilize the strongly coupled fixed point. Finally, we provide a detailed account of the Josephson current–phase relationship along the arms of the network, near each one of the allowed fixed points. Our results evidence remarkable similarities between the phase diagram accessible to a Y -junction of superconducting Josephson chains and the one found in the analysis of quantum Brownian motion on frustrated planar lattices.
Wire networks; Phase transitions in model systems; Josephson junction arrays
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/20.500.11770/158456
 Attenzione

Attenzione! I dati visualizzati non sono stati sottoposti a validazione da parte dell'ateneo

Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 45
  • ???jsp.display-item.citation.isi??? 42
social impact