Just seven photons can mimic a billion!
Matter and radiation are the two entities with which the entire universe is composed of. Matter, one of the entities of universe, is made up of a large number of molecules. The transition from one state to another occurs at the same transition points, irrespective of the number of molecules constituting the system. During such transitions -known as phase transitions- abrupt changes in the behaviour of molecules occur.
Can the other entity of universe, radiation, behave in a similar way? As we know, photons can be considered as the fundamental particles of radiation. When the temperature of the system approaches absolute zero, a system with a large number of photons will show a phase transition in which most of the photons will accumulate to the ground state- a phenomenon known as Bose-Einstein Condensation.
Can the same system show similar phase transition when the number of photons is reduced to less than ten? With an apparatus consisting of fluorescent dye and curved mirrors, scientists from Imperial College London, University of Oxford and Karlsruhe Institute of Technology, Germany, showed that such a transition to Bose-Einstein Condensate is possible if the number of added photons becomes just seven!