Rapid, Site-Selective Loading of a Scalable Array of Trapped Ions

Rapid trap reloading is a requirement for any scalable quantum information processor based on trapped-ion qubits. Even cryogenic systems with trap lifetimes in excess of 10 hours will require loading rates of approximately 100 s$^{-1}$ to maintain arrays of millions of ions. Further, the reloading process should not introduce unacceptable levels of decoherence into other ions within the array. Here, we demonstrate rapid, site-selective, random-access loading of a 2x2 array of trapped ions that satisfies the major criteria for scalable quantum processing. This scheme uses a continuous flux of pre-cooled strontium atoms and a pair of orthogonal photo-ionization lasers to load surface-electrode point Paul traps at average rates greater than 400 s$^{-1}$. Additionally, we have conducted a series of Ramsey experiments to measure the effects of loading on the coherence of nearby trapped ions. C. D. Bruzewicz, R. McConnell, J. Chiaverini, and J. M. Sage, arXiv:1511.03293 (2015).