1. 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

2. PROJECT TITLE: Comparative Study between CCJJ and CCJJ+DC
STUDENTS: Mostafa El Demery
SUPERVISOR: DR. Yuri Shukrinov
LAB: Bogoliubov Laboratory of Theoretical Physics (BLTP)

3. LAYOUT Some History Josephson Effect Josephson Junctions
Capacitively Coupled Josephson Junctions
Our Investigation

4. 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.

5. Some History 1962: Josephson effect and Josephson Junctions.
1963: Anderson experimentally verified Supercurrent to be existed.

6. 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.

7. Josephson Junction
Josephson Effect

8. 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

9. Josephson Junctions Types (cont.)
Weak Link (SNS Sandwich) S N
Weak Link
Superconductor (S)
Normal Metal (N) or Superconductor

10. Capacitively Coupled Josephson Junctions
System of superconducting layers with indices l and order parameter
and time-dependent phase
Gauge invariant phase difference

11. Capacitively Coupled Josephson Junctions
Generalized Josephson Relation GJR
α is the coupling constant between junctions.

12. 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

13. Comparative Study between CCJJ and CCJJ+DC (Cont.)
Without Noise Periodic BCs With Noise

14. Comparative Study between CCJJ and CCJJ+DC (Cont.)
Without Noise Non Periodic BCs With Noise

15. Comparative Study between CCJJ and CCJJ+DC (Cont.)

16. Interjunction coupling between IJJ
CCJJ

17. Thank you for attention

18. Acknowledgement