Динамика переходов коротких и длинных джозефсоновских контактов

• Автор: Ауджелло Джузеппе
• Шифр специальности: 01.04.03
• Научная степень: Кандидатская
• Год защиты: 2012
• Место защиты: Нижний Новгород
• Количество страниц: 101 с. : ил.

Federal State Educational Institution of Higher Professional Education “Lobachevsky State University of Nizhni Novgorod”
A manuscript
AUGELLO Giuseppe
TRANSIENT DYNAMICS OF SHORT AND LONG JOSEPHSON JUNCTIONS
01.04.03 — Radiophysics
DISSERTATION for the degree Candidate of Physical and Mathematical Sciences
Supervisors: Ph.D., Professor Spagnolo Bernardo (Italy), Candidate of Physical and Mathematical Sciences, Associate Professor Dubkov Alexander Alexandrovich
N izhni Novgorod
Contents
1 Introduction
1.1 Transient Dynamics and Josephson Junctions
1.2 Brief Review on Superconductivity and Josephson Junction
J.3 Quantum computing and Josephson Junctions
1.4 Effects of noise in Josephson Junctions
1.4.1 Short and Long Josephson Junctions
1.4.2 Noise Induced Effects: resonant activation and noise
enhanced stability
1.4.3 Thermal Noise in Short. Josephson Junctions
1.4.4 Low Frequency Noise in Josephson Junctions
1.4.5 Non-GaiiKsian Noise in Josephson junctions
1.4.C Thermal Noise in Long .Josephson Junctions
1.5 Colored and Non-Gaussian Noise in Josephson Junctions: overview
of the project
2 Short Josephson Junctions
2.1 Equivalent Circuit and Mechanical Model
2.2 Colored Noise
2 3 Effects of Colored Noise
2.4 Non-Gaussian Noise
2.5 Effects of non-Gaussiau Noise
2.6 Simultaneous action of non-Gaussian and thermal noise
8 Long Josephson Junctions
3.1 Equivalent Circuit and Mechanical Model
3.2 Correlated Noise and sine-Gordon Equation
3 3 Effects of Colored Noise
3 4 Simultaneous Action of Colored and Thermal White Noise
4 Conclusions
4.1 Main results of this work
4.2 Future research projects
Bibliography
A Algorithm for the Simulation of Stable Random Variables
A.i Stable Variables and Distributions
A.2 Simulation Algorithm

CONTENTS
B Algorithm for the Numerical Integration of the sine-Gordon Equation
C Publications
C.l Papers in IS1 Journals
C.2 Proceedings
C.3 Abstracts in international conferences

Short Josephson Junctions
I'his chapter is foe used on the effects of Gaussian and non-Gaussian noise on !he transient dynamics of short Josephson junctions. Jn section 2.1 the RSJ model, the archetypal model for the study of SJJ, is presented. In section
2.2 peculiarities of Gaussian correlated noise (colored noise) are explained In section 2.3 the results concerning the application of colored noise and the efte< ts of both white and colored noise are shown. In section 2.4 the properties of non-Gaussian noise signals arc presented. In section 2.5 and
2.C tile, study of the effects of non-Gaussian noise and both non-Gaussian and thermal noise are reported.
2.1 Equivalent Circuit and Mechanical Model
I'he Josephson effect accounts for the presence of a tunneling effect of charge earners (Coopci-pairs) in a Josephson junction in the limit of low temperatures (T —> 0 (sec. 1.2)) In a ieal situation the tempeiatiue has a finite value. Even at von low temperature, under the thermal activation regime (se<. 1.1). together with the Cooper-pairs, single electrons arc present in the supereondiK tors In this case two kinds of current, flowing in the junction, have to be distinguished: supercurrent. ip{l). and siugle-olectron or quasi-particle current, i(j(i) [50]. The supercurrent is due to the Cooper-pairs tunneling, whirl] is a function of the phase difference and vanishes when rp = 0. The quasi-particle current describes the normal current flowing in the junction due to the electron drift, which is a function of the potential difference V(i) across the junction and vanishes when V(f) = 0. The quasipart idc current has features in common with currents in normal metals and irnriiisic semiconductors. The electrons constituting iq(L) are accelerated by the external potential applied to the junction and scattered by phonon and impurity mechanisms. The scattering mechanisms are responsible for dissipation processes in the conduction. The geometry of a junction plays also