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Graduate Lecture Series 29 June – 3 July, 2009 Prof Ngee-Pong Chang

Graduate Lecture Series 29 June – 3 July, 2009 Prof Ngee-Pong Chang. Lecture 5 Superconductivity Flux Quantization & SQUID. Kammerlingh Onnes 1853-1926 On the Sudden Rate at Which the Resistance of Mercury Disappears Communications of the Leiden Laboratory, 1911.

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Graduate Lecture Series 29 June – 3 July, 2009 Prof Ngee-Pong Chang

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  1. Graduate Lecture Series 29 June – 3 July, 2009 Prof Ngee-Pong Chang Lecture 5 Superconductivity Flux Quantization & SQUID

  2. Kammerlingh Onnes 1853-1926 On the Sudden Rate at Which the Resistance of Mercury Disappears Communications of the Leiden Laboratory, 1911

  3. Onnes-Holst measurement of Hg resistance

  4. Meissner Effect 1933 Robert Ochsenfeld Walther Meissner 1882 - 1974

  5. Inside sphere

  6. Superconductivity

  7. Drude’s Theory of Conductivity Perfect conductor Limit

  8. London’s Equations Superconductor Is better than perfect conductor London’s Equation London’s Equation

  9. London Equations Fritz London

  10. Proc Roy Soc A149, 71, 1935

  11. Maxwell’s Equations for Superconductor

  12. http://web.mit.edu/6.763/www/FT03/Lectures/Lecture17.pdf#search=%22superconducting%20phase%20diagram%20lecture%22

  13. http://web.mit.edu/6.763/www/FT03/Lectures/Lecture17.pdf#search=%22superconducting%20phase%20diagram%20lecture%22

  14. John Bardeen Leon Cooper John R. Schrieffer BCS Theory of Superconductivity Phys.Rev.108, 1175 (1957)

  15. Superconductor Charge Density In Absence of Magnetic Field Cooper Pair has zero momentum

  16. In absence of Magnetic Field momentum In presence of Magnetic Field momentum

  17. In the Presence of Magnetic Field Cooper Pair with zero momentum

  18. charge density is constant phase depends on vector potential Superconducting Current Superconducting current

  19. Quantization of Flux

  20. Deep inside

  21. Deep inside fluxoid

  22. Fluxoid Quantization B.Deaver & W. Fairbank Phys Rev Lett 7, 43 (1961)

  23. Brian D. Josephson 1940 -

  24. Vo II I

  25. Vo II I

  26. Josephson Current

  27. D.C. Josephson effect Anderson & Rowell experiment, 1963 For V ≠ 0 , JDC = 0 For V = 0 , JDC = Jo sin δo P.W. Anderson

  28. A.C. Josephson Current

  29. A.C. Josephson Current

  30. SQUID a Ca P Q Cb b Coupled Josephson Junctions in an external magnetic field

  31. SQUID current for general Flux a Ca P Q Cb b

  32. SQUID

  33. SQUID Biomagnetic Device

  34. Look to the Galaxies

  35. Is terrestrial physics different than celestial ?

  36. 10-12 August, 2005 Nanyang Technological UniversityNational University of SingaporeBiopolis, A*STAR

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