Coherent Optical Memory Baesd on A Laser-written On-chip Waveguide

Abstract

Quantum memory is the core device for the construction of large-scale quantum networks. For scalable and convenient practical applications, integrated optical memories, especially on-chip optical memories, are crucial requirements because they can be easily integrated with other on-chip devices. Here, we report the coherent optical memory based on a type-IV waveguide fabricated on the surface of a rare-earth ion-doped crystal (i.e. $\mathrm{E}{\mathrm{u}}^{3+}$:${\mathrm{Y}}_2\mathrm{Si}{\mathrm{O}}_5$). The properties of the optical transition (${}^7\mathrm{F}{}_0\to {}^5\mathrm{D}{}_0$) of the $\mathrm{E}{\mathrm{u}}^{3+}$ ions inside the surface waveguide are well preserved compared to those of the bulk crystal. Spin-wave atomic frequency comb storage is demonstrated inside the type-IV waveguide. The reliability of this device is confirmed by the high interference visibility of $97\pm 1\%$ between the retrieval pulse and the reference pulse. The developed on-chip optical memory paves the way towards integrated quantum nodes.

7 pages, 5 figures