Abstract

We compare the atomic coherence time of doped ion crystals, i.e., BiPO₄: Eu³⁺, YPO₄: Eu³⁺, YPO₄: Pr³⁺, and Y₂SiO₅: Pr^3 +crystals. Such atomic coherence time is controlled by crystal field splitting (CF-splitting) and optical (photon and phonon) dressing. Compared with the other doped ion crystals, BiPO₄: Eu³⁺ exhibits the longest coherence time. By controlling thermal phonon, phase-transition phonon, broadband or narrowband excitation, and fluorescence (FL) or spontaneous four-wave-mixing ratio (S-FWM), a superior atomic coherence time of up to 10 ± 0.6 ms is achieved in the pure hexagonal (0.5:1) phase of BiPO₄: Eu³⁺. Furthermore, the relationship between TAT-splitting and spectral Autler–Townes (SAT)-splitting was investigated. This superior atomic coherence time has potential applications in quantum memory devices.

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