Quantum resonance. Sequence of 3 computer models showing the development of quantum resonance in a cavity. At left, two quantum wavefunctions spread out from their start point as circular waves. They hit semicircular barriers (black) and reflect back and forth (centre). Wavelengths of the right size will resonate in the cavities and accumulate. This corresponds to trapping particles (like electrons) of a certain energy. Because they also behave as waves, diffraction also occurs and the waves can leak past the edges of the barriers and through holes. This started at centre, and further spread of the waves is seen at right. This model was created as an artwork by Professor Eric Heller.