Testing QED in sodium-like gold and xenon: Using atomic spectroscopy and an EBIT to probe the quantum vacuum

Abstract

Electron Beam Ion Traps (EBITs) can strip atoms to their electronic cores, revealing strong perturbations of the quantum vacuum that occur at electric field strengths comparable to those in petawatt lasers focused to their diffraction limit. Wavelengths of the D-lines in sodiumlike ions measured previously using the NIST EBIT are discussed in terms of testing quantum electrodynamics in the high-field limit. The accuracy of our measurements in Au68+ (0.03 eV), together with the estimated accuracy of a corresponding calculation (0.02 eV), provide a 0.6% test of QED, the most precise currently available in any sodium-like ion. This measurement tests the predictions of QED for sodium-like ions to more fractional accuracy than even the best results available in hydrogen-like uranium. For the case of Na-like Xe43+, where a modest discrepancy exists between theory and measurements from three independent groups, an apparent collisionenergy dependence is revealed which may account for the discrepancy. © 2010IOP Publishing Ltd and SISSA.