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Bose-Einstein Condensate

Bose-Einstein Condensate. By Kyle Ireton and Ian Winter. What is it?. BEC consists of particles cooled down to a temperature within a few billionths of a degree centigrade above absolute zero These particles exist in a state of matter that is neither solid, liquid, nor gas

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Bose-Einstein Condensate

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  1. Bose-Einstein Condensate By Kyle Ireton and Ian Winter

  2. What is it? • BEC consists of particles cooled down to a temperature within a few billionths of a degree centigrade above absolute zero • These particles exist in a state of matter that is neither solid, liquid, nor gas • This is the coldest state of matter in the known universe

  3. How cold is that? • BEC exists at around 1 x 10-9K • The coldest recorded temperatures on Earth is about -89.40 °C, or 183.75 K (Antarctica) • The coldest known naturally occurring temperature is about 3 K (outer space) • For about a century, we have been able to cool matter below 3 K with powerful freezers • For a while, we have been able to get matter down to about 1 x 10-5 K with laser cooling

  4. How long have we known about BEC? • The combined efforts of SatyendraNath Bose and Albert Einstein first predicted that BEC-like behavior would be possible in the 1920’s

  5. Bose’s Contribution • Satyendra Bose was a brilliant Indian mathematical physicist • Studied how the quantum theory applied to light, where photons are discrete energy packets • The main idea of his work was to treat photons as identical particles • Could not get work published

  6. Einstein’s Contribution • Einstein recognized Bose’s brilliance, translated his articles into German, used influence to get them published • Also, generalized his rules for identical photons to apply to atoms • Hypothesized that atoms lowered to the lowest possible quantum state would condense into an indistinguishable mass

  7. Defining Bose-Einstein Condensate • BEC properties can be explained by de Broglie wavelengths, according to the equation λdB= [(2π ħ2) / (kBmT)]1/2 • De Broglie wavelengths describe the wavelike behavior of matter • Matter does not usually exhibit wavelike behavior because wavelengths are too small

  8. λdB= [(2π ħ2) / (kBmT)]1/2 • As temperature decreases, wavelengths increase • At low enough temperatures, wavelengths of individual atoms begin to overlap • As the wave functions interfere with each other, the atoms become indistinguishable • Thus, quantum mechanical properties can be observed

  9. Quantum Energy Level Explanation • As we all remember from last term… Electrons in orbit around an atom exist at discrete energy levels • Like electrons, atoms also have discrete energy levels

  10. Atom Energy Levels • BEC behavior is observed in atoms at the lowest possible quantum level (ground state) • When they exist at the same energy level, overlap occurs • Individual particles cannot be distinguished because they form a condensed state of low-energy matter

  11. Demonstration of BEC • http://colorado.edu/physics/2000/bec/what_is_it.html

  12. How is it made? • Lasers of the right frequency can slow down particles, reducing temperature (1 x 10-5 K) • Evaporative cooling is used to cool the particles further, down to 1 x 10-9 K • Magnets form a “bowl” from which particles of higher energy levels escape, further lowering avg. temperature

  13. So, what does it look like? • The quantities of BEC being currently produced are only observable by microscope • According to the University of Colorado (where BEC was first produced in 1995), the particles in the magnetic bowl condensed like water condensed into a dew

  14. A snapshot of Bose-Einstein Condensate This image was captured by the University of Colorado (http://colorado.edu/physics/2000/bec/what_it_looks_like.html) the numbers refer to temperature, the coldest samples are BEC

  15. Applications? (Why should we care?) • Many potential applications arise from the coherence of the particles • Coherence makes the particles much easier to manipulate • Most important application may be modeling

  16. How long must we wait? • BEC is a relatively new discovery, being produced for the first time in only 1995 • It may take decades, or longer, for the greater potential of BEC to be realized • Will we see benefits from BEC applications in our lifetime? • This question remains to be answered

  17. References • University of Colorado http://www.colorado.edu/physics/2000/bec/ • Calcuttaweb.com http://www.calcuttaweb.com/people/snbose.shtml • Physicsworld.com http://physicsworld.com/cws/article/print/2242 • Nova (PBS) http://www.pbs.org/wgbh/nova/zero/atoms.htmlhttp://www.pbs.org/wgbh/nova/zero/program.html

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