High-accuracy calculation of black-body radiation shift in ¹³³Cs primary frequency standard

الأصل · EN

Black-body radiation (BBR) shift is an important systematic correction for the atomic frequency standards realizing the SI unit of time. Presently, there is a controversy over the value of the BBR shift for the primary ¹³³Cs standard. At room temperatures the values from various groups differ at 3 × 10⁻¹⁵ level, while the modern clocks are aiming at 10⁻¹⁶ accuracies. We carry out high-precision relativistic many-body calculations of the BBR shift. For the BBR coefficient β at T=300K we obtain β=-(1.708±0.006) × 10⁻¹⁴, implying 6 × 10⁻¹⁷ fractional uncertainty. While in accord with the most accurate measurement, our 0.35%-accurate value is in a substantial, 10%, disagreement with recent semi-empirical calculations. We identify an oversight in those calculations.