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EFFECT OF DIFFUSION CURRENT (DC) ON CAPACTIVELY COUPLED JOSEPHSON JUNCTIONS (CCJJ) COMPARATIVE STUDY BETWEEN CCJJ AND CCJJ+DC. Practice of students from ARAB REPUBLIC OF EGYPT 2009. PROJECT. TITLE : Comparative Study between CCJJ and CCJJ+DC STUDENTS : Mostafa El Demery
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EFFECT OF DIFFUSION CURRENT (DC) ON CAPACTIVELY COUPLED JOSEPHSON JUNCTIONS (CCJJ)COMPARATIVE STUDY BETWEEN CCJJ AND CCJJ+DC Practice of students from ARAB REPUBLIC OF EGYPT 2009
PROJECT • TITLE: Comparative Study between CCJJ and CCJJ+DC • STUDENTS: Mostafa El Demery • SUPERVISOR: DR. Yuri Shukrinov • LAB: Bogoliubov Laboratory of Theoretical Physics (BLTP)
LAYOUT • Some History • Josephson Effect • Josephson Junctions • Capacitively Coupled Josephson Junctions • Our Investigation
Some History • 1911: Onnes discovered Superconductivity. • 1933: Meissner and Ochsenfeld discovered the perfect diamagnetism. • 1950: London, Ginsburg and Landau formulated a phenomenological theories of Superconductivity. • 1957: Bardeen, Cooper and Schrieffer formulated a microscopic theories of Superconductivity.
Some History • 1962: Josephson effect and Josephson Junctions. • 1963: Anderson experimentally verified Supercurrent to be existed.
Josephson Effect • Novel phenomena should arise in a weak electrical contact between two superconductors (Josephson Junction). • Supercurrent component in the net current flowing through the junction is responsible for these phenomena. • Supercurrent is a function not of the voltage V across the junction but of the phase-difference Josephson Phase.
Josephson Effect Josephson Junction
Josephson JunctionsTypes S I S Types • Tunnel Junctions (SIS Sandwich) • Proposed in 1960 by Giaever. • Superconductor (S)-insulator (I)-superconductor (S). • Electrons have a small but nonvanishing probability of penetrating from one electrode to the other one via quantum tunneling through the energy barrier by the insulator. • Electron penetration results in a nonvanishing normal conductance Gn when the electrodes are in • Normal State • Superconducting State Tunnel Junction
Josephson JunctionsTypes (cont.) S S Types • Weak Link (SNS Sandwich) N Weak Link
Capacitively Coupled Josephson Junctions • System of superconducting layers with indices l and order parameter and time-dependent phase • Gauge invariant phase difference
Capacitively Coupled Josephson Junctions • Generalized Josephson Relation GJR • α is the coupling constant between junctions.
Comparative Study between CCJJ and CCJJ+DC CCJJ CCJJ+DC Total current flowing through junctions is • Total current flowing through junctions is System of dynamical equations for the phase difference
Comparative Study between CCJJ and CCJJ+DC (Cont.) CCJJ CCJJ+DC Without Noise Periodic BCs With Noise
Comparative Study between CCJJ and CCJJ+DC (Cont.) CCJJ CCJJ+DC Without Noise Non Periodic BCs With Noise
Comparative Study between CCJJ and CCJJ+DC (Cont.) CCJJ CCJJ+DC