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Title. “When freezing cold is not cold enough - new forms of matter close to absolute zero temperature” Wolfgang Ketterle Massachusetts Institute of Technology MIT-Harvard Center for Ultracold Atoms 9/2/09 Meridian Lecture Space Telescope Science Institute Baltimore. What is energy.

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  1. Title “When freezing cold is not cold enough - new forms of matter close to absolute zero temperature” Wolfgang Ketterle Massachusetts Institute of TechnologyMIT-Harvard Center for Ultracold Atoms 9/2/09Meridian Lecture Space Telescope Science Institute Baltimore

  2. What is energy Quantum Gases The coldest matterin the universe

  3. What is temperature What is temperature? A measure of energy One form of energy is motion(kinetic energy).

  4. Cold particles move slowly Hot particlesare fast

  5. What is the lowest temperatures possible?

  6. What is temperature Zero degree Kelvin(-273 degrees Celsius, -460 degrees Fahrenheit) is the zero point for energy

  7. The highest temperature is infinite (In principle it is possible for particles to have arbitrarily high kinetic energies –until they become so heavy (due to E=mc2) that they from a black hole – at the Planck temperature of 1032 K)

  8. What is temperature What is the differencein temperature betweensummer and winter? 20 %

  9. How cold is interstellar space? 3 K

  10. Nanokelvin temperatures How cold is itin our laboratories? Nanokelvin:A billion timescolder than interstellar space

  11. Nanokelvin temperatures Why can you makenew discoveriesat cold temperatures?

  12. Nobel medal

  13. Atom slow down They slow down 600 mph (300 m/sec) 1 cm/sec What happens to atomsat low temperatures? They march in lockstep

  14. Molecule of the year Matter made of waves!

  15. Molecule of the year

  16. Why do photons not Bose condense What is Bose Einstein Condensation? Population per energy state Bose-Einstein distribution T=Tc Energy

  17. Why do photons not Bose condense T<Tc Condensate! What is Bose Einstein Condensation? Population per energy state Bose-Einstein distribution Energy

  18. Why do photons not Bose condense What is Bose Einstein Condensation? T<Tc Condensate! Population per energy state Bose-Einstein distribution Energy

  19. Laser beam and light bulb Photons/atoms are one big wave Photons/atoms moving randomly Ordinary light Laser light

  20. Bose/Einstein * 1925

  21. BE statistics and black body law Gases (Atoms and Molecules) Black-Body Radiation “Photons” Max Planck

  22. The concepts The cooling methods • Laser cooling • Evaporative cooling

  23. Hot atoms

  24. Laser beams Hot atoms

  25. Fluorescence Laser beams Hot atoms

  26. Laser beams Fluorescence If the emitted radiation is blue shifted (e.g. by the Doppler effect) ….

  27. Laser beams Cold atoms: 10 – 100 K Fluorescence Chu, Cohen-Tannoudji, Phillips, Pritchard, Ashkin, Lethokov, Hänsch, Schawlow, Wineland …

  28. MOT Laser cooling 2.5 cm

  29. The concepts Evaporative cooling

  30. Magnetic trap setup (GIF) Phillips et al. (1985) Pritchard et al. (1987)

  31. Guinness Book Record

  32. The real challenge One challenge … experimental complexity

  33. WK and Dark SPOT Sodium laser cooling experiment (1992)

  34. Sodium BEC I experiment (2001)

  35. Evaporative cooling Dave Pritchard Dan Kleppner Tom Greytak

  36. Family tree I.I. Rabi PhD Norman Ramsey PhD Dan Kleppner PhD PhD PhD Under- graduate Dave Pritchard Postdoc RandyHulet Bill Phillips Postdoc PhD Eric Cornell Wolfgang Ketterle Carl Wieman

  37. Key factors for success: • Funding • Technical infrastructure • Excellent collaborators • Tradition and mentors

  38. Probing BEC How do we show that the Bose-Einstein condensate has very low energy?

  39. Magnetic trap setup • The condensate • a puff of gas • 100,000 thinner than air • size comparable to the • thickness of a hair • magnetically suspended in an ultrahigh vacuum chamber

  40. Effusive beam Effusive atomic beam Gas How to measure temperature? Kinetic energy mv2/2 = kBT/2

  41. Effusive beam Effusive atomic beam Gas How to measure temperature? Kinetic energy mv2/2 = kBT/2

  42. CCD

  43. CCD Ballistic expansion: direct information about velocity distribution

  44. Absorption image: shadow of atoms CCD Ballistic expansion: direct information about velocity distribution

  45. BEC B&W AVI The shadow of a cloud of bosonsas the temperature is decreased (Ballistic expansion for a fixed time-of-flight) Temperature is linearly related to the rf frequency which controls the evaporation

  46. Hour distribution Distribution of the times when data images were takenduring one year between 2/98-1/99

  47. Key factors for success: • Some funding • Technical infrastructure • Excellent collaborators • Tradition and mentors

  48. Key factors for success: • Some funding • Technical infrastructure • Excellent collaborators • Tradition and mentors • Physical endurance

  49. Molecule of the year How can you prove that atoms march in lockstep? Atoms are one single waveAtoms are coherent

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