Coherent emission from rare-earth ions in electrooptic crystals

Mohan Li, P. Zhang, Jiawen Li +5 more

Andrei Faraon

I present our progress towards developing optical quantum memories based on photonic crystal cavities fabricated in rare-earth-doped crystals. These devices exhibit large spontaneous emission rate enhancement, enabling optical control of single rare-earth ion quantum bits.

贾继奎 Jia Ji-kui, 侯兰香 Hou Lan-xiang

L. F. Johnson, A. A. Ballman

We report the observation of coherent emission from three rare-earth ions in electro-optic crystals. Oscillation is observed from Nd3+ ions in Bi4Ge3O12, LiNbO3, and Ba0.75Ca0.25Nb26O at room temperature, and from Tm3+ and Ho3+ ions in LiNbO3 at 77°K. Second-harmonic radiation is obtained from LiNbO3:Tm3+ and electric-field modulation of threshold is observed for certain crystals of LiNbO3:Nd3+. The latter effect is believed to arise from crystal strain. The propagation angle for phase-matched second-harmonic generation is calculated to lie at 43° to the c axis for both LiNbO3:Tm3+ and LiNbO3:Ho3+ at 77°K. Phasematched second-harmonic generation from LiNbO3:Nd3+ is not possible, since the maser line is an extraordinary wave. However, the polarization of the maser line in LiNbO3:Nd3+ is appropriate for phasematched parametric frequency conversion in the near infrared. Attempts to observe such radiation were not successful due to the limited power available in the fundamental.

Zihua Chai, Zhaocong Wang, Xinghang Chen +8 more

Rare-earth ions in bulk crystals are excellent solid-state quantum systems in quantum information science owing to their exceptional optical and spin coherence properties. However, the weak fluorescence of single rare-earth ions presents a significant challenge for scalability, necessitating the integration into microcavities. Thin films serve as a promising material platform for the integration, yet fabrication without compromising the properties of the materials and rare-earth ions remains challenging. In this work, we fabricate micrometer-thin yttrium aluminum garnet (YAG) films from bulk crystals using ion implantation techniques. The resulting films preserve the single-crystalline structure of the original bulk crystal. Notably, the embedded rare-earth ions are photostable and exhibit bulk-like spin coherence properties. Our results demonstrate the compatibility of bulk-like spin properties with the thin-film fabrication technique, facilitating the efficient integration of rare-earth ions into on-chip photonic devices and advancing the applications of rare-earth ions in quantum technologies.