Bose-Einstein condensation

1. When Atoms Become Waves Bose-Einstein condensation presentation by Dr. K.Y. Rajpure

2. Phenomenon Particles Half integral spin Integral multiple spin Fermions Bosons Enrico Fermi Satyendra Nath Bose Obey Pauli exclusion principle Possible to put a large group of atoms in a single quantum state No two identical fermions can be in the same quantum state at same time. presentation by Dr. K.Y. Rajpure

3. BEC historical background Bose - statistics for photons (the particles which make up light). Albert Einstein - adapted the work to apply it to other Bosonic particles and atoms. At a finite T, almost all of ples in a Bosonic system would congregate in the GND state. Quantum wave fns of each particle start to overlap, Atoms get locked into phase with each other, And loose their individual identity. "Bose-Einstein condensation" presentation by Dr. K.Y. Rajpure

4. Absolute temperature presentation by Dr. K.Y. Rajpure

5. Absolute temp graph 5000 K. surface of the sun 300 to 400 K. boiling and freezing points of water 70 K. the freezing point of N2, high Tc superconductivity 3 K. superconductivity and superfluidity. Now possible to cool atomic systems to one millionth of a degree Kelvin, and even lower. At these extreme temperatures, the world is an utterly strange place where our everyday's common sense is useless, quantum physics rules with its counterintuitive laws, and atoms behave as waves. presentation by Dr. K.Y. Rajpure

6. de Broglie’s wavelength: A French prince and waves of matter  = h / p as p ­ associated . presentation by Dr. K.Y. Rajpure

7. de Broglie’s wavelength/ 3 presentation by Dr. K.Y. Rajpure

8. CoolingAtoms Above "conventional" methods, Magnetic trap 20 nK 2000 Rb atoms, This is the lowest temperature ever achieved. presentation by Dr. K.Y. Rajpure

9. 2. Doppler cooling presentation by Dr. K.Y. Rajpure

10. Sisyphus cooling presentation by Dr. K.Y. Rajpure

11. 4. Evaporative cooling presentation by Dr. K.Y. Rajpure

12. Method to achieve BEC presentation by Dr. K.Y. Rajpure

13. Method to achieve BEC/ 2 How to cool atoms ? Higher Velocity atoms  Medium Velocity atoms  Lower Velocity atoms  LASER  Magnetic field  Atoms are cooled by laser beams from all directions They are confined by the laser beam and magnetic field After optical laser cooling, the light is turned OFF and the atom cloud is confined in the magnetic field. presentation by Dr. K.Y. Rajpure

14. MOT imagined picture LASER and Magnetic Field Arrangements presentation by Dr. K.Y. Rajpure

15. BEC result/ 1 presentation by Dr. K.Y. Rajpure

16. BEC result/ 4 The three pictures, obtained by the group of W. Ketterle at MIT, show the velocity distribution in the atomic sample, Zero velocity is at the center of the pictures. The left picture : relatively high temperature, above the transition from "normal" gas to condensate. Broad velocity distribution with smooth distribution decreasing from the maximum at v = 0. Lower temperatures (middle picture) Curve shape : qualitative change. Two distinct contributions, a broad one quite similar to that of the preceding case, and superimposed to it a sharply peaked one, also centered at v = 0. This contribution : fraction of atoms that form a condensate at the bottom of the trap. Right picture, which corresponds to the lowest temperature, the broad distribution has all but disappeared, all atoms finding themselves in the condensate. presentation by Dr. K.Y. Rajpure

17. Interference Experimental proof of de Brogile’s hypothesis: Ketterle’s first interference pattern. The interference pattern between two expanding condensates resembles that formed by throwing two stones into still water. presentation by Dr. K.Y. Rajpure

18. Atom lasers presentation by Dr. K.Y. Rajpure

19. Condensate Atoms studied to date presentation by Dr. K.Y. Rajpure

20. Some more about BEC….. A BEC first achieved at 10:54 a.m. June 5, 1995, in a laboratory at JILA, a joint institute of CU-Boulder and NIST. The apparatus that made it is now at the SmithsonianInstitution. Made visible by a video camera, the condensate looks like the pit in a cherry except that it measures only about 20microns in diameter or about one-fifth the thickness of a sheet of paper. Bose-Einstein condensate of about 2,000 rubidium atoms that lasted for 15 seconds to 20 seconds. New machines can now make condensates of much greater numbers of atoms that last for up to 3 minutes. presentation by Dr. K.Y. Rajpure

21. Applications: What is Bose-Einstein condensation good for ? Too new and we know too little about it for me to give you an answer. There are also some engineeringproblems that will have to be solved before BEC can be used for very much. Today, scientists around the world are manipulating condensates made from a variety of gases to probe their scientific properties. The condensate can be used to form an atomiclaser and could one day lead to a better atomicclock. Made possible by nudging super-cold atoms into a beam, the breakthrough could lead to a new technique for making extremely small computerchips, according to NIST Nobel Laureate William Phillips, who led the team. Eventually, such a device might be able to construct nano-devices one atom at a time. Jin and DeMarco cooled atoms that are fermions, the other class of quantum particles found in nature. This was important to physicists because the basic building blocks of matter -- electrons, protons and neutrons -- are all fermions. presentation by Dr. K.Y. Rajpure

22. Nobel prize 2001 The Nobel Prize in Physics 2001 The Royal Swedish Academy of Sciences has awarded the Nobel Prize in Physics for 2001jointly to Eric A. Cornell, Wolfgang Ketterle and Carl E. Wieman “for the achievement of Bose-Einstein condensation in dilute gases of alkali atoms, and for early fundamental studies of the properties of the condensates”. presentation by Dr. K.Y. Rajpure

23. Prof. Pierre Meystre - AvH Fellow Professor of Optical Sciences and Physics The University of Arizona Dr. C.D. Lokhande - AvH Fellow My dear participants Thanks to.... presentation by Dr. K.Y. Rajpure