This article is about the physical phenomenon. For the television program, see Quantum Leap.

In physics, a quantum leap or quantum jump is a change of an electron within an atom from one energy state to the next. This is a discontinuous change in which the electron goes from one energy level to another without passing through any intermediate levels. This phenomenon contradicted expectations set by theories older than quantum mechanics that energy should always change continuously.

More generally, a quantum leap is the smallest possible change, as when one's bank account balance goes from $500.00 (five hundred dollars) to $500.01 (five hundred dollars and one cent). There are no possible amounts intermediate between those.

Vernacular, slang, or metaphorical usage

In the vernacular, the term quantum leap has come to mean an abrupt change, especially an advance or augmentation. The term dates back to early-to-mid-20th century.

It is sometimes said that a phrase such as 'a quantum leap in technology' is inappropriate, because 'quantum' supposedly means 'small' in quantum mechanics, so a 'quantum leap' would be a 'small advance'. However, 'quantum' does not actually mean 'small' in quantum mechanics; it means 'indivisible' or 'all-at-once'; but that indivisible logically implies smallest-possible. A quantum leap is an advance that happens all at once, rather than gradually over time. If advances are classified as either evolutionary or revolutionary, then a quantum leap would be the latter.

External links

• Are there quantum jumps?
• Plancks Strahlungsformel Oder die Entdeckung der Quanten.
• Der Quantensprung im Bohrschen Atommodell
• Anmerkungen zum Quantensprung
• Der Quantensprung in Zeitlupe