We investigate the transport properties of a one-dimensional superconductor-normal metal-superconductor (S-N-S) system described within the tight-binding approximation. We compute the equilibrium dc Josephson current and the time-dependent oscillating current generated after the switch on of a constant bias. In the first case an exact embedding procedure to calculate the Nambu-Gorkov Keldysh Green’s function is employed and used to derive the continuum and bound states contributions to the dc current. A general formalism to obtain the Andreev bound states (ABSs) of a normal chain connected to superconducting leads is also presented. We identify a regime in which all Josephson current is carried by the ABS and obtain an analytic formula for the current-phase relation in the limit of long chains. In the latter case, the condition for perfect Andreev reflections is expressed in terms of the microscopic parameters of the model, showing a limitation of the so-called wide-band-limit (WBL) approximation. When a finite bias is applied to the S-N-S junction we compute the exact time evolution of the system by solving numerically the time-dependent Bogoliubov-de Gennes equations. We provide a microscopic description of the electron dynamics not only inside the normal region but also in the superconductors, thus gaining more information with respect to WBL-based approaches. Our scheme allows us to study the ac regime as well as the transient dynamics whose characteristic time scale is dictated by the velocity of multiple Andreev reflections.

Perfetto, E., Stefanucci, G., Cini, M. (2009). Equilibrium and time-dependent Josephson current in one-dimensional superconducting junctions. PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS, 80(20) [10.1103/PhysRevB.80.205408].

Equilibrium and time-dependent Josephson current in one-dimensional superconducting junctions

Perfetto, E;STEFANUCCI, GIANLUCA;CINI, MICHELE
2009-01-01

Abstract

We investigate the transport properties of a one-dimensional superconductor-normal metal-superconductor (S-N-S) system described within the tight-binding approximation. We compute the equilibrium dc Josephson current and the time-dependent oscillating current generated after the switch on of a constant bias. In the first case an exact embedding procedure to calculate the Nambu-Gorkov Keldysh Green’s function is employed and used to derive the continuum and bound states contributions to the dc current. A general formalism to obtain the Andreev bound states (ABSs) of a normal chain connected to superconducting leads is also presented. We identify a regime in which all Josephson current is carried by the ABS and obtain an analytic formula for the current-phase relation in the limit of long chains. In the latter case, the condition for perfect Andreev reflections is expressed in terms of the microscopic parameters of the model, showing a limitation of the so-called wide-band-limit (WBL) approximation. When a finite bias is applied to the S-N-S junction we compute the exact time evolution of the system by solving numerically the time-dependent Bogoliubov-de Gennes equations. We provide a microscopic description of the electron dynamics not only inside the normal region but also in the superconductors, thus gaining more information with respect to WBL-based approaches. Our scheme allows us to study the ac regime as well as the transient dynamics whose characteristic time scale is dictated by the velocity of multiple Andreev reflections.
2009
Pubblicato
Rilevanza internazionale
Articolo
Sì, ma tipo non specificato
Settore FIS/03 - FISICA DELLA MATERIA
English
Con Impact Factor ISI
Perfetto, E., Stefanucci, G., Cini, M. (2009). Equilibrium and time-dependent Josephson current in one-dimensional superconducting junctions. PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS, 80(20) [10.1103/PhysRevB.80.205408].
Perfetto, E; Stefanucci, G; Cini, M
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2108/96977
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