Identical particles Identical particles Identical particles, also called indistinguishable or indiscernible particles, are particles that cannot be distinguished from one another, even in principle. Species of identical particles include, but are not limited to elementary particles such as electrons, composite subatomic particles such as atomic nuclei, as well as atoms and molecules. Quasiparticles also behave in this way. Although all known indistinguishable particles are "tiny", there is no exhaustive list of all possible sorts of particles nor a clear-cut limit of applicability, as explored in quantum statistics. There are two main categories of identical particles: bosons, which can share quantum states, and
Evaporative cooling (atomic physics) Evaporative cooling (atomic physics) Evaporative cooling is an atomic physics technique to achieve high phase space densities which optical cooling techniques typically can not reach. Atoms trapped in optical or magnetic traps are cooled as the trap depth is decreased and the hottest atoms (with the highest kinetic energy) leave the trap. The hot atoms leaving the trap are on the tail of the Maxwell-Boltzmann distribution and therefore carry away a significant amount of kinetic energy, mitigating the loss of atoms by an overall increase in phase space density. The technique is analogous to cooling a hot cup of coffee