The tiny influence that quantized sound waves called phonons have on atomic energy levels has been measured for the first time by physicists at the University of Heidelberg in Germany. Known as the "phononic Lamb shift", the effect is predicted by the theory of quantum electrodynamics (QED), which describes how charged particles interact with quanta of light. Markus Oberthaler and colleagues say that their experimental techniques – which use Bose–Einstein condensates (BEC) to simulate the behaviour of phonons rather than conventional phonons in a crystal lattice – could be extended to test other predictions of QED.

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