http://www.digitaljournal.com/tech-and-science/science/new-phase-of-light-holds-the-key-to-quantum-encryption/article/588016

New phase of light holds the key to quantum encryption

Posted Apr 6, 2021 by Tim Sandle
A new phase of light has been discovered. This has been named a "super photon". It is formed of thousands of individual light particles (photons). This could help unlock quantum encryption.
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The discovery was made at the University of Bonn and it has been described as a completely new light source. The "super photon" has been named an optical Bose-Einstein condensate (the fifth state of matter). Another term is an overdamped phase of light. This means the amplitude of the vibration decreases.
In this state, light particles are no longer distinguishable as they have moved into the same quantum mechanical state, behaving as a single giant "super-particle”, or a single wave function (a mathematical description of the quantum state of an isolated quantum system).
The discovery was made after physicists trapped light particles in a resonator formed of two curved mirrors spaced just over a micrometer apart. The mirrors function to reflect a rapidly reciprocating beam of light. Within the space between the mirrors, a liquid dye is added, which works to cool down the photons as dye molecules consume and regurgitate the photons.
The colorful Light Tunnel at Detroit Metropolitan Wayne County International Airport connecting Conc...
The colorful Light Tunnel at Detroit Metropolitan Wayne County International Airport connecting Concourse A with Concourse B/C in the McNamara Terminal. Light patterns along the tunnel are choreographed with music.
Steve Hopson
The translucent mirrors then trigger the photons to be lost and replaced. This produces a non-equilibrium, and this creates a condition between an oscillating phase and a damped phase. Damped means that the amplitude of the vibration decreases. As there is no set boundary between these two states, scientists can manipulate the light so that it moves back and forth between the oscillating and damped phases. The transition is very much like the one that occurs between water and ice. This is a phenomenon that is called a phase transition in physics.
The following video explains more about the discovery:
The significance of the discovery could have potential for boosting encrypted quantum communication, although this is not something that can be realized in the short term.
The research is titled “Observation of a non-Hermitian phase transition in an optical quantum gas” and it appears in the journal Science.