Population trapping in atoms with hyperfine structure and nuclear decay

David F. Zaretsky, S. B. Sazonov

David F. Zaretsky, S. B. Sazonov

The new method of Doppler‐free nuclear spectroscopy is propsed. The method is based on the resonance interaction of bichromatic laser light with the atom having the hyperfine structure in its ground state. The population of hyperfine components in the model Λ‐case is calculated and the polarization rate dependence on the laser powers and the phase difference is established. The case of nonstable atoms is considered and the angular distribution of nuclear decay γ‐quanta is calculated. The ways of experimental realization of the method proposed are discussed.

Jian Wang, Chuji Wang, Re Lai +1 more

Xi‐Jing Ning

A five-level quantum system including two low-lying states and three excited states of the ladder type coupled with four laser fields is investigated as it relates to dressed-atom models, and a dressed state is found to be independent of the ionization decaying from the highest level. Under general conditions, half of the initial population of the two low-lying states is trapped in the dressed state, leading to a low probability of ionization. Based on the analytical results, two schemes are proposed for removing population trapping. For a five-level system with hyperfine structures, such as the system for ionizing 235U atoms, population trapping takes place when the laser fields are weak and can be gotten rid of by an increase in laser intensity.

Alexandr I. Magunov, I. Rotter, С. И. Страхова

Wu Wang, Fen Zou, S. Fritzsche +1 more

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.