the cage becomes an atom
the cage becomes an atom
Three dimensions of freedom: a continuous sea of electrons, their energies smearing into broad, unbroken bands.
Two dimensions of freedom: the sea narrows to a sheet.
One dimension of freedom: the sheet narrows to a wire.
Zero dimensions of freedom: the cage closes completely.
When an electron is confined in all three spatial dimensions—a quantum dot—the continuum shatters. The broad bands of the bulk material are replaced by discrete, perfectly isolated energy levels.
It is an artificial atom. But where a natural atom's properties are fixed by the immutable laws of chemistry and the charge of its nucleus, the artificial atom's properties are dictated entirely by the physical dimensions of the cage. To change its color, you do not change its element; you simply change its size.