STEM
When electrons transition to lower energy levels photons corresponding to specific wavelengths are released but if the atoms are cooled close to absolute zero then some atoms end up occupying the same state. However, this was not observed until 1995 when Rubidium-87 atoms were cooled to 170 nanokelvins by Carl Wiemen, Eric Cornell and Wolfgang Ketterle and for this experiment they were awarded the 2001 Nobel Prize in Physics. Bose-Einstein condensates are extremely useful for observing quantum effects especially because it is on a macroscopic level. For example, superfluidity is one quantum property they exhibit, and it essentially means that Bose-Einstein condensates have zero viscosity; so, there is no resistance to their flow. Bose- Einstein condensates can also demonstrate superconductivity which is when certain materials experience no electrical resistance below a critical temperature. This research on Bose-Einstein condensates may seem to only benefit our understanding of quantum mechanics with novel observations of ultracold atoms but it does have potential practical applications. For example, they could be used in quantum computers to communicate information due to the fact that all the atoms in a Bose-Einstein condensate are in precisely the same state. Bose-Einstein condensates could also be utilised in high precision measurement schemes through atom interferometry. Atom interferometry makes precise measurements of anything that disrupts the quantum waves of the atoms in a Bose- Einstein condensate such as a gravitational or magnetic field. Overall, on the approach to absolute zero an astonishing range of quantum phenomena becomes observable and whilst the applications of Bose-Einstein condensates are still being explored they provide a valuable insight into the quantum world and the wonderfully weird nature of Physics.
The closer to absolute zero the smaller the amount of energy each particle has. From this idea you might reasonably assume that if particles were at absolute zero, they would have zero energy, but this is not the case due to the Heisenberg uncertainty principle. The Heisenberg uncertainty principle states that it is impossible to know the position and momentum of an object perfectly at the same time and if particles had zero energy, we would know their location and that they have no momentum. Therefore, at absolute zero, particles must retain some vibrational motion, also known as zero-point energy, in order to obey the laws of the uncertainty principle. Near absolute zero physicists can prove theories on quantum physics by looking at the energy of the particles, but they can also observe the increasingly strange behaviour of matter, in the form of Bose-Einstein condensates. Bose-Einstein condensates may be referred to as the fifth state of matter and they are formed by cooling low-density gases comprised of bosons (subatomic particles with no spin) to 100 trillionths of a kelvin above absolute zero, at which point the wavelike nature of particles is observable. To put it simply, waves and particles are not mutually exclusive and near absolute zero the wave nature of particles is prominent. At these incredibly low temperatures atoms have very little energy so some start grouping together and entering the same state until they become undistinguishable. These atoms end up with the exact same wavelength and behave as though they were a singular atom which can be described as a ‘super atom’ or quantum wave. These Bose-Einstein condensates were first theorised in the early 20th century when Indian physicist Satyendra Nath Bose was working on statistical problems in quantum mechanics. He sent his ideas to Albert Einstein and together they found that atoms must have specific energy levels, which is why electrons are in discrete orbitals.
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