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Bose einstein condensate


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Bose einstein condensate

  2. 2.  In our daily experience, most of us deal with three phases of matter : solid, liquid and gas.  A fourth high energy phase of matter, plasma occurs in high energy processes as near as a fire or as far away as the core of a star.  For decades, the existence of a fifth lower energy form of matter known as Bose Einstein Condensate(BECs),was only a theoretical possibility.  In 2001, the Noble Prize for physics went to Eric Cornell, Wolfgang Ketterle, and Carl Wieman, who used lasers,magnets,and evaporative cooling to bring about this fascinating new phase of matter.
  3. 3. Bose-Einstein condensate (BEC), a state of matter which is formed by cooling a gas of extremely low density ,about one hundred thousandth the density of normal air ,to super low temperatures . They can slow light down to the residential speed limit, flow without friction . They are effectively super atoms, groups of atoms that behave as one.
  4. 4.  The theory of BECs was developed by Satyendra Nath Bose and Albert Einstein in the early 1920s. Bose combined his work in thermodynamics and statistical mechanics with the quantum mechanical theories that were being developed, and Einstein carried the work to its natural conclusions and brought it to the public eye.At the time, none of the necessary technology was available to make BECs in the lab: cryonics were extremely limited, and the first laser wasn't even built until 1960. The fine control allowed by modern computers was also a prerequisite. Because of all of these technological hurdles, it wasn't until 1995 that experimenters were able to force rubidium atoms to form this type of condensate. FOUNDERS
  5. 5. Solids have the lowest energy levels (corresponding with the lowest temperatures), while liquids and gases have increasingly higher levels. At the top end of this scale, we can add plasmas, which are energetic enough to emit all kinds of energy in the form of heat and photons. Bose-Einstein Condensates represent a fifth phase of matter beyond solids. They are less energetic than solids. We can also think of this as more organized than solids, or as colder -- BECs occur in the fractional micro-Kelvin range, less than millionths of a degree above absolute zero; in contrast, the vacuum of interstellar space averages a positively tropical 3 K. BEC S AS COMPARED TO THE OTHER STATES OF MATTER
  6. 6.  BECs are more ordered than solids in that their restrictions occur not on the molecular level but on the atomic level.  Atoms in a solid are locked into roughly the same location in regard to the other atoms in the area.  Atoms in a BEC are locked into all of the same attributes as each other; they are literally indistinguishable, in the same location and with the same attributes.  When a BEC is visible, each part that one can see is the sum of portions of each atom, all behaving in the same way, rather than being the sum of atoms as in the other phases of matter
  7. 7.  Most research into Bose-Einstein Condensates serves as "basic" research -- that is to say, it is more concerned with knowing more about the world in general than with implementing a specific technology. However, there are several potential uses for BECs. The most promising application is in etching.  When BECs are fashioned into a beam, they are like a laser in their coherence. That is to say, both a laser and a BEC beam run "in lock step," guaranteeing that an experimenter can know how a part of the beam will behave at every single location. This property of lasers has been used in the past for etching purposes. A BEC beam would have greater precision and energy than a laser because even at their low kinetic energy state, the massive particles would be more energetic than the massless photons. PROPERTIES AND FUTURE APPLICATIONS
  8. 8. • The major technological concerns with a BEC beam would be getting a clean enough environment for it to function repeatedly and reducing the cost of BEC creation enough to use BECs regularly in beams. However, BEC beams or "atom lasers" could produce precisely trimmed objects down to a very small scale -- possibly a nanotech scale. Their practical limits will be found with experimentation
  9. 9. • One of the most commonly known properties of BECs is their super fluidity. That is to say, BECs flow without interior friction. • Since they're effectively super atoms, BECs are all moving in the same way at the same time when they flow, and don't have energy losses due to friction. • Even the best lubricants currently available have some frictional losses as their molecules interact with each other, but BECs, while terribly expensive, would pose no such problem.
  10. 10. • One of the problems physicists run into when teaching quantum mechanics is that the principles are just counter-intuitive. • They're hard to visualize. • But videos of BEC blobs several millimetres across show wave-particle duality at a level we can comprehend easily. • We can watch something that acts like an atom, at a size we could hold in our hands. • MIT researchers have produced visible interference fringe patterns from sodium BECs, demonstrating quantum mechanics effects on the macro scale.
  11. 11. • Perhaps most interestingly, BECs have been used to slow the speed of light to a crawl -- from 186,282 miles per second (3x108 m/s) in a vacuum to 38 miles per hour (17 m/s) in a sodium BEC. • No other substance so far has been able to slow the speed of light within orders of magnitude of that speed. • Although so far this discovery has not been applied to any technological problems, researchers at Harvard suggest that it might make possible revolutions in communications, including possibly a single-photon switch.
  12. 12. • The Bose-Einstein Condensate is to matter as the laser is to light -- the analogy is precisely that simple. • It took twenty years from the invention of the laser until its technological applications began to take off. • At first, lasers were considered too difficult to make to ever find use in everyday applications; now, they're everywhere. • The characteristics of BECs, specifically their response to sound and other disturbances, are still under investigation, but they hold the promise of many curious developments to come.
  13. 13. • ates_of_matter • densate • einstein.shtml • REFRENCES