Stringent test of QED with hydrogen-like tin

Abstract

Inner-shell electrons naturally sense the electric field close to the nucleus, which can reach extreme values beyond 1015 V cm−1 for the innermost electrons1. Especially in few-electron, highly charged ions, the interaction with the electromagnetic fields can be accurately calculated within quantum electrodynamics (QED), rendering these ions good candidates to test the validity of QED in strong fields. Consequently, their Lamb shifts were intensively studied in the past several decades2,3. Another approach is the measurement of gyromagnetic factors (g factors) in highly charged ions4–7. However, so far, either experimental accuracy or small field strength in low-Z ions5,6 limited the stringency of these QED tests. Here we report on our high-precision, high-field test of QED in hydrogen-like 118Sn49+. The highly charged ions were produced with the Heidelberg electron beam ion trap (EBIT)8 and injected into the ALPHATRAP Penning-trap setup9, in which the bound-electron g factor was measured with a precision of 0.5 parts per billion (ppb). For comparison, we present state-of-the-art theory calculations, which together test the underlying QED to about 0.012%, yielding a stringent test in the strong-field regime. With this measurement, we challenge the best tests by means of the Lamb shift and, with anticipated advances in the g-factor theory, surpass them by more than an order of magnitude.

Electrostatic anharmonicity in cylindrical Penning traps induced by radial holes to the trap center

“…Experiments that are based on precision measurements of the particle oscillation frequencies beyond this level would need to account for such shifts when introducing radial holes, see for example precision mass measurements [38][39][40][41] and determinations of magnetic moments with single particles [42][43][44]. In such experiments, the frequency resolution ω/Δω of 10 9 and beyond is several orders of magnitude better than the expected frequency shift due to radial holes.…”

Testing quantum electrodynamics in extreme fields using helium-like uranium

“…Only very recently, a measurement in the mid- Z range has been performed, on hydrogen-like tin ( Z = 50) (ref. 24 ) in which, however, two-loop QED effects could not yet be tested because of deficiencies in the theoretical predictions.…”

The Landé g factors of highly charged Sn47+ and Bi80+ ions

“…The highly charged Sn q+ and Bi q+ ions are very important in many applications, such as astrophysical plasmas [16], and precision measurement physics [17,18]. Recently, the H-like 118 Sn 49+ ions were trapped in a Penning trap [19], and the g factor was measured with an accuracy of 10 −12 [19]. The g factor of Li-like 209 Bi 80+ ions was measured at the experimental storage ring at the GSI Helmholtz Center for Heavy Ion Research in Darmstadt [18].…”