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Title. “New forms of quantum matter near absolute zero temperature” Wolfgang Ketterle Massachusetts Institute of Technology MIT-Harvard Center for Ultracold Atoms 5/23/06 NASA workshop Airlie Center. Title. The ongoing revolution in atomic physics …. Title.

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  1. Title “New forms of quantum matter near absolute zero temperature” Wolfgang Ketterle Massachusetts Institute of TechnologyMIT-Harvard Center for Ultracold Atoms 5/23/06 NASA workshop Airlie Center

  2. Title The ongoing revolution in atomic physics …

  3. Title Enabling technology:Nanokelvin temperatures

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

  5. Sodium BEC I experiment (2001)

  6. Guinness Book Record

  7. Height of atmosphere e-(106) 300 mK h=1 cm Potential (gravitational) energy mgh = kBT/2 (g: gravitational acceleration) How to measure temperature Height of the atmosphere 1 nK h= 30 nm 300 K h=10 km In thermal equilibrium: Potential energy ~ kinetic energy

  8. Lowest temperature ever achieved: 450 picokelvin 1.05 nK 1 cm 780 pK Trapping a sodium BECwith a single coil 450 pK A.E. Leanhardt, T.A. Pasquini, M. Saba, A. Schirotzek, Y. Shin, D. Kielpinski, D.E. Pritchard, and W. Ketterle, Science 301, 1513 (2003). Temperature measurement by imaging the size of the trapped cloud

  9. Precision measurements Precision measurements with Bose-Einstein condensates ... We have to get rid of perturbing fields … • Gravity • Magnetic fields

  10. What distinguishes nanokelvin? • Physics • BEC Phase transition Quantum reflection • Interactions • Ease of Manipulation

  11. BEC at JILA and MIT BEC @ JILA, June ‘95(Rubidium) BEC @ MIT, Sept. ‘95 (Sodium)

  12. Quantum Reflection of Ultracold Atoms T.A. Pasquini, Y. Shin, C. Sanner, M. Saba, A. Schirotzek, D.E. Pritchard, W.K. • Phys. Rev. Lett. 93, 223201 (2004) • Preprint (2006)

  13. Sodium BEC Silicon surface

  14. Quantum Reflection from Nanopillars Solid Si surface Reduced density Si surface Reflection Probability Velocity (mm/s) 1 mm/s is 1.5 nK x kB kinetic energy

  15. What distinguishes nanokelvin? • Physics • BEC Phase transition Quantum reflection • Interactions • Ease of Manipulation

  16. Moving condensates Loading sodium BECs into atom chipswith optical tweezers 44 cm Atom chip with waveguides BECproduction BECarrival T.L.Gustavson, A.P.Chikkatur, A.E.Leanhardt, A.Görlitz, S.Gupta, D.E.Pritchard, W. Ketterle, Phys. Rev. Lett. 88, 020401 (2002).

  17. Splitting of condensates 1mm One trappedcondensate 15ms Expansion Two condensates

  18. Splitting of condensates 1mm Trapped 15ms expansion Two condensates

  19. Splitting of condensates Two condensates Very recent progress: 200 ms coherence time for an atom chip interferometer Y. Shin, C. Sanner, G.-B. Jo, T. A. Pasquini, M. Saba, W. Ketterle, D. E. Pritchard, M. Vengalattore, and M. Prentiss:Phys. Rev. A 72, 021604(R) (2005).

  20. Splitting of condensates Two condensates Atom interferometry: Matter wave sensors The goal: Use ultracold atoms to sense Rotation  Navigation Gravitation  Geological exploration

  21. What distinguishes nanokelvin? • Physics • BEC Phase transition Quantum reflection • Interactions • Ease of Manipulation

  22. Two of the biggest questions in condensed matter physics: The nature of high-temperature superconductors Quantum magnetism, spin liquids Strongly correlated, strongly interacting systems

  23. Title How to get strong interactions? Pair A-B Particle A Particle B

  24. Title Resonant interactions have infinite strength Pair A-B Particle A Particle B • Unitarity limited interactions: • Pairing in ultracold fermions • Relevant to quark-gluon plasmas

  25. E Free atoms Molecule Magnetic field Feshbach resonance

  26. Disclaimer: Drawing is schematic and does not distinguish nuclear and electron spin. E Free atoms Molecule Magnetic field Feshbach resonance

  27. Two atoms …. E Free atoms Molecule Magnetic field Feshbach resonance

  28. … form an unstable molecule E Free atoms Molecule Magnetic field Feshbach resonance

  29. … form a stable molecule E Free atoms Molecule Magnetic field Feshbach resonance

  30. Atoms attract each other E Free atoms Molecule Magnetic field Feshbach resonance

  31. Atoms repel each other Atoms attract each other E Free atoms Molecule Magnetic field Feshbach resonance

  32. Atoms repel each other Atoms attract each other Force between atoms Scattering length Magnetic field Feshbach resonance

  33. Title Observation of High-Temperature Superfluidity in Ultracold Fermi Gases

  34. At absolute zero temperature … Bose-Einstein condensation  atoms as waves  superfluidity Fermi sea:  Atoms are not coherent  No superfluidity Bosons Particles with an even number of protons, neutrons and electrons Fermions Particles with an odd number of protons, neutrons and electrons

  35. Pairs of fermions Particles with an even number of protons, neutrons and electrons Two kinds of fermions Fermi sea:  Atoms are not coherent  No superfluidity

  36. At absolute zero temperature … Pairs of fermions Particles with an even number of protons, neutrons and electrons Bose-Einstein condensation  atoms as waves  superfluidity Two kinds of fermions Particles with an odd number of protons, neutrons and electrons Fermi sea:  Atoms are not coherent  No superfluidity

  37. Weak attractive interactions Cooper pairs larger than interatomic distance momentum correlations  BCS superfluidity Two kinds of fermions Particles with an odd number of protons, neutrons and electrons Fermi sea:  Atoms are not coherent  No superfluidity

  38. Electron pairs Atom pairs Bose Einstein condensate of molecules BCS Superconductor

  39. Atoms attract each othera<0 Atoms repel each othera>0 Energy Atoms Molecules Magnetic field Molecules are unstable Atoms form stable molecules BCS-limit: Condensation of long-range Cooper pairs BEC of Molecules: Condensation of tightly bound fermion pairs

  40. Atom pairs Bose Einstein condensate of molecules BCS superfluid

  41. BCS superfluid Molecular BEC

  42. Magnetic field BCS superfluid Molecular BEC

  43. Crossover superfluid BCS superfluid Molecular BEC

  44. Fermi energy Fermi temperature (density)2/3 high Tc superfluid 0.3 High-temperature superfluidity at 100 nK? Transition temperature Binding energy of pairs  10-5 … 10-4normal superconductors 10-3superfluid 3He 10-2high Tc superconductors Scaled to the density of electrons in a solid:Superconductivity far above room temperature!

  45. Preparation of an interacting Fermi system in Lithium-6 Optical trapping @ 1064 nm naxial = 10-20 Hznradial= 50–200 Hz Etrap = 0.5 - 5 mK States |1> and |2> correspond to |> and |>

  46. Title How to show that these gases are superfluid?

  47. Rotating buckets

  48. Quantized circulation Quantization: Integer number of matter waves on a circle

  49. Vortex structure

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