Magnetically Purified Erbium-doped Oxide Crystal--Towards Creating a Quantum-information-manipulation Platform
Takehiko Tawara, Tomohiro Inaba · NTT technical review · 2019
Erbium (Er) is a rare-earth element that is expected to be a platform for manipulation of quantum information by utilizing telecommunication-wavelength photons.However, high-quality epitaxial growth of Er-doped host crystals is difficult, and the memory time of quantum information, which determines the performance of quantum manipulation, is much shorter than theoretically predicted.We investigated a good-compatibility rare-earth oxide as a host crystal for Er.The host oxide crystal, cerium oxide (CeO 2 ), had its nuclear spin removed (i.e., magnetically purified).The nuclear spin is the main factor that shortens the lifetime of quantum-information retention time.In this article, we describe high-quality epitaxial growth of CeO 2 and its optical properties as a thin film grown on a silicon substrate.