quantum jump

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Abrupt change from one energy level to another, especially such a change in the orbit of an electron with the loss or gain of a quantum of energy.
• noun A quantum leap.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a sudden large increase or advance
• noun (physics) an abrupt transition of an electron or atom or molecule from one quantum state to another with the emission or absorption of a quantum