Molecular Physics
Magnetic interactions in Pr3+ : LiYF4for quantum manipulation : search for an efficient three-level Λ system
Philippe Goldner, O. Guillot-Noël
Abstract
The influence of an external magnetic field on the hyperfine structure of the 3 H4(0) and 1D2(0) crystal field states of Pr3+ in LiYF4 is studied in order to find an efficient three-level Λ system. Using an experimentally determined spin Hamiltonian, we show that three-level Λ systems can be obtained with equal strengths for the optically excited transitions under various magnetic field magnitudes and orientations. An analytical analysis based on two levels is proposed to find useful magnetic fields without extensive numerical calculations and to understand the general behaviour of the system. Pr3+ hyperfine structure has also been directly calculated using a complete Hamiltonian including free ion, crystal field and magnetic interactions. A good agreement with the spin Hamiltonian approach is found for the ground state whereas the excited state results poorly reproduce the experiment. This is attributed to the low accuracy of 1D2 crystal field wavefunctions. This suggests that transition strengths ratios could be calculated directly from the crystal field Hamiltonian with improved crystal field parameters.