Deep Drive into the Bose-Einstein Condensate

Image Credit: NIST/JILA/CU-Boulder, via Wikimedia Commons.

Were you taught in school that there are three states of matter? Maybe four? Get ready to deep drive beyond those teachings because there are no less than seven.

Bose-Einstein Condensate (BEC)  is a state of matter that occurs very close to absolute zero. At this acutely low temperature, molecular motion almost stops and atoms begin to bundle together. It is a state of matter of a dilute gas of bosons cooled to temperatures very close to absolute zero. Under such conditions, a huge fraction of bosons occupy the lowest quantum state, at which point nano quantum phenomena, particularly wave function interference, become apparent. A BEC is produced by cooling a gas of extremely low density, about one-hundred-thousandth the density of normal air, to ultra-low temperatures. In the year 1924-1925, this state was adumbrate by Satyendra Nath Bose and Albert Einstein. Satyendra Nath Bose first sent a paper to Einstein on the quantum statistics of light quanta (now called photons), in which he stated and derived Planck's quantum radiation law without any reference to classical physics. In the year 1924, Einstein translated this paper himself from English to German and submitted it for Bose to the Zeitschrift für Physik after he was impressed with statement that was given by Satyendra Nath Bose regarding the quantum statistics. Later Einstein extended the Bose’s ideas to matter in two other papers. This results into a concept which was known as Bose Gas and this is governed by Bose-Einstein Statistics. 

What is Boson?

The statistical allotment of identical particles with integer spin, now called bosons. Bosons, which include the photon as well as atoms such as helium-4 (4He), are allowed to share a quantum state. Einstein proposed that cooling bosonic atoms to a very low temperature would cause them to fall (or "condense") into the lowest accessible quantum state, resulting in a new form of matter. An amazing characteristic of bosons is that their statistics do not restrict the number of them that occupy the same quantum state. This property is demonstrated by helium-4 when it is cooled to become a superfluid. Unlike bosons, two identical fermions unable to immerse the same quantum space. Whereas the elementary particles that make up matter (i.e. leptons and quarks) are fermions, the elementary bosons are force carriers that function as the 'glue' holding matter together.[10] This property holds for all particles with integer spin (s = 0, 1, 2, etc.) as a consequence of the spin–statistics theorem. When a gas of Bose particles is cooled down to temperatures very close to absolute zero, then the kinetic energy of the particles decreases to a negligible amount, and they condense into the lowest energy level state. This state is called Bose-Einstein condensation. It is believed that this property is the explanation of superfluidity. Examples of bosons include fundamental particles such as photons, gluons, and W and Z bosons (the four force-carrying gauge bosons of the Standard Model), the recently discovered Higgs boson, and the hypothetical graviton of quantum gravity. Some composite particles are also bosons, such as mesons and stable nuclei of even mass number such as deuterium (with one proton and one neutron, mass number = 2), helium-4, or lead-208[Note 1]; as well as some quasiparticles (e.g. Cooper pairs, plasmons, and phonons). In the year 1938 Fritz London contemplated BEC as a mechanism for superfluidity in 4He and superconductivity. On June 5, 1995 the first gaseous condensate was developed by Eric Cornell and Carl Wieman at the University of Colorado at BoulderNIST–JILA lab, in a gas of rubidium atoms cooled to 170 nanokelvins (nK). Shortly thereafter, Wolfgang Ketterle at MIT classified important BEC properties. For their achievements Cornell, Wieman, and Ketterle received the 2001 Nobel Prize in Physics. Many isotopes were soon condensed, then molecules, quasi-particles, and photons in 2010.