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 This is the coldest state of matter in the known universe

How cold is that? BEC exists at around 1 x K The coldest recorded temperatures on Earth is about °C, or 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 K with laser cooling

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

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

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

Defining Bose-Einstein Condensate BEC properties can be explained by de Broglie wavelengths, according to the equation λ dB = [(2π ħ 2 ) / (k B mT)] 1/2 De Broglie wavelengths describe the wavelike behavior of matter Matter does not usually exhibit wavelike behavior because wavelengths are too small

λ dB = [(2π ħ 2 ) / (k B mT)] 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

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

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

Demonstration of BEC l l

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

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

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

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

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

References University of Colorado Calcuttaweb.com Physicsworld.com Nova (PBS)