| 1. | Physics. an abrupt transition of a system described by quantum mechanics from one of its discrete states to another, as the fall of an electron in an atom to an orbit of lower energy. |
| 2. | any sudden and significant change, advance, or increase. |
| quantum leap n. An abrupt change or step, especially in method, information, or knowledge: "War was going to take a quantum leap; it would never be the same" (Garry Wills). |
| quantum jump
A change from one quantum state to another, as when an electron orbiting a nucleus moves from one shell to another with the loss or gain of a quantum of energy. |
quantum leap
A dramatic advance, especially in knowledge or method, as in Establishing a central bank represents a quantum leap in this small country's development. This term originated as quantum jump in the mid-1900s in physics, where it denotes a sudden change from one energy state to another within an atom. Within a decade it was transferred to other advances, not necessarily sudden but very important ones.