Isomeric Population Transfer of the ^{229}Th Nucleus via Hyperfine Electronic Bridge

The electronic bridge (EB) excitation of nuclei has been found as a versatile approach to efficiently excite the ^{229}Th isomers. Previous studies on EB excitation have typically disregarded the hyperfine structure as well as the decay of the excited atoms and ions by just treating the nucleus-electron coupling perturbatively. In the present work, we apply a quantum-optical approach to nonperturbatively investigate EB excitation of ^{229}Th^{3+} ions. This approach considers both the hyperfine structure and atomic decay through dressed hyperfine state and quantum master equation techniques. Numerical results show that the isomeric steady-state population of the time-independent scheme is constrained by atomic decay to a maximum of only 27.9%. By leveraging the dark state, however, the (time-dependent) stimulated Raman adiabatic passage method theoretically reaches a remarkable 99.7% isomeric population transfer and demonstrates a potential nuclear-laser scheme via the EB mechanism. Our quantum-optical approach exhibits a large flexibility and paves a promising avenue for utilizing advanced quantum-control technologies to design and optimize experimental schemes of EB excitation.