Phase transition filter from controllable hybrid line shape of correlation and squeezing of Pr3+: YPO4 and Eu3+: YPO4

We report the symmetry-dependent intensity-noise correlation and the intensity-difference squeezing of spontaneous parametric four-wave mixing (SP-FWM) and fluorescence (FL) hybrid signals from the different phases [hexagonal (H) + tetragonal (T), T + H] of Pr3+: YPO4 and Eu3+: YPO4 crystals. The competition between FL and SP-FWM in hybrid signals determines the amplitude and hybrid line shape of the two-mode and three-mode correlation. The correlation amplitude switches from positive to negative due to strong double dressing caused by a high transition probability and a dipole moment of the (more H + less T)-phase of Pr3+: YPO4. This switching phenomenon is used to realize a metal-oxide semiconductor field-effect transistor-based logic inverter. Furthermore, the line shape of correlation changes from broad to sharp due to weak dressing, transition probability, and a low dipole moment of the (more T + less H)-phase of Pr3+: YPO4. Based on these results, we proposed the model of a tunable correlation filter. Gate position, frequency detuning, and laser power control the amplitude and hybrid line shape. Our experimental results provide an advanced technique of bandwidth contrast of about 0.9%. Such notch filters have potential applications in quantum communications.

Automated summary

The study reports the intensity-noise correlation and intensity-difference squeezing of hybrid signals from different phases of Pr3+: YPO4 and Eu3+: YPO4 crystals. Competition between FL and SP-FWM determines the amplitude and line shape, with the correlation amplitude switching from positive to negative due to strong double dressing in one phase. The results suggest a tunable correlation filter model for applications such as quantum communications, with amplitude and line shape controlled by gate position, frequency detuning, and laser power.