Measurement of the reduced dipole matrix element in Ba⁺

2026/07/23 by N. Jayjong, M. D. K. Lee, K. J. Arnold +1
#physics.atom-ph #quant-ph

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Abstract

We present a high-precision measurement of the reduced electric-dipole matrix element ⟨ P_1/2‖r‖S_1/2⟩ in ¹³⁸Ba⁺. By comparing off-resonant scattering rates with dispersive Stark-shift measurements, we determine the matrix element to be 3.322 7(12), corresponding to a P_1/2 excited-state radiative lifetime of 7.866 3(56)~ns. Combining our experimental results with a prior model for the differential scalar polarizability Δα₀(ω), we extract the static value Δα₀(0) = -73.09(12)a.u. This determination directly improves the evaluation of the blackbody radiation (BBR) shift, minimizing a prominent systematic limitation in room-temperature Ba⁺ optical clock error budgets. These results provide a stringent benchmark for atomic-structure calculations and advance high-precision applications in quantum metrology and tests of fundamental physics.

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