Lamb shift

noun

A small difference between the energy levels 2S_½ and 2P_½ of the hydrogen atom, not predicted by the Dirac equation, whose detection in the Lamb–Retherford experiment of 1947 foreshadowed the development of quantum electrodynamics (in which the discrepancy is explained to be an effect of the emission and re-absorption of virtual photons); such a difference between otherwise expectedly equal energy levels of hydrogen or any other type of atom.

Meanings

nounLamb shift (plural Lamb shifts)

plural Lamb shifts

  1. quantum mechanics; quantum electrodynamics; quantum mechanics; quantum electrodynamicsA small difference between the energy levels 2S_½ and 2P_½ of the hydrogen atom, not predicted by the Dirac equation, whose detection in the Lamb–Retherford experiment of 1947 foreshadowed the development of quantum electrodynamics (in which the discrepancy is explained to be an effect of the emission and re-absorption of virtual photons); such a difference between otherwise expectedly equal energy levels of hydrogen or any other type of atom.

    Whilst I was there, I became interested in the possibility of measuring Lamb shifts in hydrogenic ions using radio-frequency spectroscopy (1) and laser spectroscopy as a means of testing quantum electrodynamics (QED).

    2001, J. D. Silver, “Chapter 10: The Oxford EBIT”, in John Gillaspy, editor, Trapping Highly Charged Ions: Fundamentals and Applications, Nova Science Publishers, page 279
    2 more examples

    In recent years, a significant progress has been achieved in accurate measurements of the energy levels in heavy few-electron HCI including the 1s Lamb shift in H-like uranium [3.73-75], the hyperfine structure of H-like bismuth [3.69] and the ground state energies of He-like ions [3.29,20].

    1997, Heinrich F. Beyer, Heinz-Jürgen Kluge, Viatcheslav P. Shevelko, X-Ray Radiation of Highly Charged Ions, Springer, page 75

    The linear combination of the #92;textstyle 1S, #92;textstyle 2S and #92;textstyle 8D#95;#123;#92;frac 5 2#125; Lamb shifts obtained in this manner admits direct comparison with the Lamb shift theory without any further complications.

    2007, Michael I. Eides, Howard Grotch, Valery A. Shelyuto, Theory of Light Hydrogenic Bound States, Springer, page 241

Origin

Named after American physicist Willis Lamb (1913-2008).

Full word history & related roots →

Translations

French décalage de Lamb, déplacement de Lamb
  • décalage de Lambdifference between energy levels
  • déplacement de Lambdifference between energy levels
German Lamb-Verschiebung
  • Lamb-Verschiebungdifference between energy levels
Italian spostamento di Lamb
  • spostamento di Lambdifference between energy levels
Portuguese desvio de Lamb
  • desvio de Lambdifference between energy levels
Cite this entry
APA

Lamb shift. (n.d.). In WatkinsX Dictionary. Retrieved November 3, 2026, from https://dictionary.watkinsx.com/word/Lamb%20shift

MLA

“Lamb shift.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/Lamb%20shift. Accessed November 3, 2026.

Chicago

WatkinsX Dictionary, s.v. “Lamb shift,” accessed November 3, 2026, https://dictionary.watkinsx.com/word/Lamb%20shift.

Source: Lamb shift on Wiktionary, CC BY-SA 4.0.