Towards a quantum memory based on an excited-state absorption in Tm:YAP

Quantum memories compatible with telecommunication-wavelength photons are a key element towards building a large-scale quantum network, since they allow remote quantum information exchange through existing low-loss fibre infrastructure. Rare-earth ion (REI) doped crystals exhibit broad inhomogenous lines (∼GHz), allowing for large spectral multiplexing, while preserving very good coherence properties such as long coherence times (∼ms-s) leading to long storage times. Given the appeal of a quantum memory at telecom wavelength, and the difficulty in reaching high efficiencies with erbium-doped crystals, we performed spectroscopic investigations of  ³F₄↔³H₄ excited-state transition at around 1450 nm wavelength in various Tm-doped crystals. In this talk we will present recent results for Thulium-doped yttrium aluminium perovskite (Tm:YAP). We will discuss an optical hole burning scheme that allows us to assess the coherence of this transition and show that an atomic frequency comb (AFC) based quantum memory can be achieved in this platform.