Quantum realm

Quantum realm is a term of art in physics referring to scales where quantum mechanical effects become important [http://www.wired.com/science/discoveries/news/2007/04/quantum] , [http://physicsweb.org/articles/news/7/2/9/1] , [http://plato.stanford.edu/entries/qm-action-distance/] . Typically, this means distances of 100 nanometers (nm) or less. Not coincidentally, this is the same scale as Nanotechnology.

While originating on the nanometer scale, such effects can operate on a macro level. The classic example is Electron tunneling. Most fundamental processes in Molecular electronics, Organic electronics, and Organic semiconductors also originate in the quantum realm.

The quantum realm can also sometimes paradoxically involve actions at long distances. E.g., "The "quantum realm" involves curious correlations between distant events. A well-known example is David Bohm's (1951) version of the famous thought experiment that Einstein, Podolsky and Rosen proposed in 1935 (henceforth, the EPR/B experiment). Pairs of particles are emitted from a source in the so-called spin singlet state and rush in opposite directions (see Fig. 1 below). When the particles are widely separated from each other, they each encounter a measuring apparatus that can be set to measure their spin components along various directions. Although the measurement events are distant from each other, so that no slower-than-light or light signal can travel between them, the measurement outcomes are curiously correlated." [http://plato.stanford.edu/entries/qm-action-distance/] .