Coherent light-matter interfaces based on luminescent Eu3+ complexes

Coherent light-matter interactions in luminescent lanthanide (Ln3+) complexes (Figure 1a) are useful for the realization of quantum information processing (QIP) applications.[1] The interest in molecular systems stems from the fact that their optical properties can be tuned adopting molecular engineering strategies, and they can be assembled in a controllable manner as identical copies, useful for creating scalable quantum architectures. Recently, we have observed narrow homogeneous linewidth (Γh) and microsecond (μs) long optical coherence lifetime (T2) associated (Figure 1b) with a molecular europium (Eu3+) complex—[Eu(BA)4](pip), BA and pip stand for benzoylacetonate and piperidin-1-ium, respectively (Figure 1a). Taking advantage of the narrow linewidths and the presence of nuclear quadrupolar interactions, we have shown efficient polarization of nuclear spins in one of the ground state hyperfine levels and demonstrated storage of photons in the [Eu(BA)4](pip) crystal, elucidating the utility of molecular crystals as quantum memories for light. Additionally, we have also shown controlled Eu3+-Eu3+ interactions useful for the creation of quantum gate architectures.[2] This talk aims to showcase how spectroscopic properties of luminescent Ln3+ complexes can be leveraged to realize quantum technological applications—for example, in quantum communications.