Three-type Fano interference controlled by the phase transition of Eu3+/Pr3+:YPO4.

We study the Fano interference from different phase transitions of Eu³⁺:YPO₄ and Pr³⁺:YPO₄ crystals through simultaneous detection of bright and dark states. For this study, we employed tetragonal (T), hexahedral (H), and (H + T)-phases of YPO₄ crystals. The Fano interfering bright and dark states are classified based on dressed spontaneous parametric four-wave mixing, dressed multi-order fluorescence, and hybrid signal regimes. Further, the Fano interference between conti-nuous and discrete states can be controlled from partly-(constructive–destructive)-interference through a phase transition, nonlinear phase, and dressing. The (H + T)-phase Pr³⁺:YPO₄ suggests more obvious Fano interference in contrast to T- or H-phase Pr³⁺:YPO₄. We report that the Pr³⁺:YPO₄ and Eu³⁺:YPO₄ demonstrates the dressed multi-level- and dressed single-level Fano interference, respectively, with further three types of Fano interference that can be distinguished at different time delays. The experimental measurement agrees with theoretical simulations. Such results may be used for the design of new types of quantum electronic or spintronic devices such as Fano-transistors. [ABSTRACT FROM AUTHOR]