Quantum computing in rare-earth-ion-doped crystals

Abstract: Quantum computers are predicted to achieve significant speed-ups for certain applications when compared to classical computers. In this talk, I give an overview of quantum computing in rare-earth-ion-doped crystals. These systems can potentially have very high qubit densities and connectivities as the doped ions sit only nanometer apart in three dimensions. I discuss how these single-ion qubits could be read out via dedicated readout ions, and present the results of recent theoretical investigations that show that quantum processor nodes constructed in these materials can be tailored to contain between a few tens and 1000 qubits. Furthermore, the average number of qubits each qubit can interact with, denoted by the connectivity, can be partly tailored to lie between just a few and roughly 100. Lastly, I discuss how many such processor nodes are envisioned to be connected in a multi-node architecture.