Practice of students from ARAB REPUBLIC OF EGYPT 2009 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 Junction Josephson Effect
Josephson Junctions 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 S I Tunnel Junction
Josephson Junctions Types (cont.) Weak Link (SNS Sandwich) S N Weak Link Superconductor (S) Normal Metal (N) or Superconductor
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 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.) Without Noise Periodic BCs With Noise
Comparative Study between CCJJ and CCJJ+DC (Cont.) Without Noise Non Periodic BCs With Noise
Comparative Study between CCJJ and CCJJ+DC (Cont.)
Interjunction coupling between IJJ CCJJ
Thank you for attention
Acknowledgement