High precision hyperfine measurements in Bismuth challenge bound-state strong-field QED

Area of Science:

• Atomic Physics
• Quantum Electrodynamics (QED)
• Nuclear Structure

Background:

• Highly charged heavy ions, like hydrogen-like bismuth, generate extreme electromagnetic fields.
• Measuring light interactions in these ions is crucial for testing QED and electron-nucleus interactions.
• Nuclear structure uncertainties have limited rigorous testing of strong-field QED.

Purpose of the Study:

• To precisely measure the specific difference between hyperfine splittings in hydrogen-like and lithium-like bismuth.
• To provide a decisive test of QED in strong magnetic fields, minimizing nuclear structure effects.

Main Methods:

• High-precision spectroscopy of hydrogen-like and lithium-like bismuth ions (²⁰⁹Bi^82+,80+).
• Measurement of the specific difference in hyperfine splittings.

Main Results:

• Achieved over an order of magnitude improvement in measurement precision.
• Observed a 7-sigma discrepancy between the experimental results and theoretical QED predictions.

Conclusions:

• The precise measurement challenges current theoretical understanding of QED in extreme electromagnetic fields.
• Discrepancy suggests potential limitations in current QED models or nuclear structure assumptions.