Bose Einstein Condensate
There exists four states of matter namely solid, liquid, gas and plasma. The plasma state is most abundant on universe. It is in superhot state and is made up of ionised gases, which can be prominently seen in sun and stars. Bose-Einstein condensate (BEC) is a state of matter, which is a dilute gas of bosons cooled to temperatures very close to absolute zero (273.15°C). SatyendraNath Bose, an Indian physicist was the first person to notice the existence of 5th state of matter. Later, he forwarded his theory to Einstein, who further researched on this topic and published “Bose-Einstein Statistics”. In 1995, the BEC was produced by Eric Cornell and Carl Wieman by cooling atoms of Rubidium gas.
Laser cooling is a process in which atoms are cooled to very low temperature. Absolute zero temperature is achieved by this cooling method. It involves two steps- first, laser light is projected on atoms, so that they absorb photons. It promotes the atom into excited state. When atoms absorb and re-emit photons their momentum changes, resulting inslowing down and decrease in energy. In the next step, atoms recoil in opposite direction and lose most of their energy. Since atoms also behave as waves (dual nature), as their temperature decreases wavelength increases. All the waves accumulate and freeze together to form Super atom. This is called as Bose Einstein Condensate.
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APPLICATIONS
- To create atom circuits, rotation sensors
- Quantum information processing in quantum computers
- Development of optical lattices
- Helium isotope behaves as BEC at absolute zero which acts as superfluid
- Rubidium gas cooled to 0 K acts as BEC and can slow down the light speed to 17 m/s