6-Dec-15presentation by Dr. K.Y. Rajpure1 When Atoms Become Waves

6-Dec-15presentation by Dr. K.Y. Rajpure2 BosonsFermions Satyendra Nath Bose No two identical fermions can be in the same quantum state at same time. Possible to put a large group of atoms in a single quantum state Integral multiple spin Half integral spin Particles Enrico Fermi Obey Pauli exclusion principle Phenomenon

6-Dec-15presentation by Dr. K.Y. Rajpure3 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" Bose - statistics for photons (the particles which make up light). BEC historical background

6-Dec-15presentation by Dr. K.Y. Rajpure4 Absolute temperature

6-Dec-15presentation by Dr. K.Y. Rajpure K. surface of the sun 300 to 400 K. boiling and freezing points of water 70 K. the freezing point of N 2, 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. Absolute temp graph

6-Dec-15presentation by Dr. K.Y. Rajpure6 A French prince and waves of matter de Broglie’s wavelength :  = h / p as p  ­ associated  .

6-Dec-15presentation by Dr. K.Y. Rajpure7 de Broglie’s wavelength/ 3

6-Dec-15presentation by Dr. K.Y. Rajpure8 Above "conventional" methods, Magnetic trap 20 nK 2000 Rb atoms, This is the lowest temperature ever achieved. Cooling Atoms

6-Dec-15presentation by Dr. K.Y. Rajpure9 2. Doppler cooling

6-Dec-15presentation by Dr. K.Y. Rajpure10 Sisyphus cooling

6-Dec-15presentation by Dr. K.Y. Rajpure11 4. Evaporative cooling

6-Dec-15presentation by Dr. K.Y. Rajpure12 Method to achieve BEC

6-Dec-15presentation by Dr. K.Y. Rajpure13 Higher Velocity atoms  Medium Velocity atoms  Lower Velocity atoms  LASER  Magnetic field  How to cool atoms ? 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. Method to achieve BEC/ 2

6-Dec-15presentation by Dr. K.Y. Rajpure14 LASER and Magnetic Field Arrangements MOT imagined picture

6-Dec-15presentation by Dr. K.Y. Rajpure15 BEC result/ 1

6-Dec-15presentation by Dr. K.Y. Rajpure16 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. Right picture, which corresponds to the lowest temperature, the broad distribution has all but disappeared, all atoms finding themselves in the condensate. 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. 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. BEC result/ 4

6-Dec-15presentation by Dr. K.Y. Rajpure17 Ketterle’s first interference pattern. The interference pattern between two expanding condensates resembles that formed by throwing two stones into still water. Experimental proof of de Brogile’s hypothesis: Interference

6-Dec-15presentation by Dr. K.Y. Rajpure18 Atom lasers

6-Dec-15presentation by Dr. K.Y. Rajpure19 Condensate Atoms studied to date

6-Dec-15presentation by Dr. K.Y. Rajpure20 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 Smithsonian Institution. 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. Made visible by a video camera, the condensate looks like the pit in a cherry except that it measures only about 20 microns in diameter or about one-fifth the thickness of a sheet of paper. Some more about BEC…..

6-Dec-15presentation by Dr. K.Y. Rajpure21 Too new and we know too little about it for me to give you an answer. There are also some engineering problems that will have to be solved before BEC can be used for very much. 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. Made possible by nudging super-cold atoms into a beam, the breakthrough could lead to a new technique for making extremely small computer chips, 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. 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 atomic laser and could one day lead to a better atomic clock. What is Bose-Einstein condensation good for ? Applications:

6-Dec-15presentation by Dr. K.Y. Rajpure22 Nobel Prize in Physics for 2001 Eric A. Cornell The Royal Swedish Academy of Sciences has awarded the Nobel Prize in Physics for 2001 jointly to Eric A. Cornell, Wolfgang Ketterle 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”. Nobel prize 2001

6-Dec-15presentation by Dr. K.Y. Rajpure23 Prof. Pierre Meystre - AvH Fellow Professor of Optical Sciences and Physics The University of Arizona Dr. C.D. Lokhande - AvH Fellow My dear participants