J Miles, M T Lichtman, A M Scott, J Scott, S A Norrell, M J Bedalov, D A Belknap, D C Cole, S Y Eubanks, M Gillette, P Gokhale, J Goldwin, M Iliev, R A Jones, K W Kuper, D Mason, P T Mitchell, J D Murphree, N A Neff-Mallon, T W Noel, A G Radnaev, I V Vinogradov, M Saffman
We demonstrate an interspecies entangling Rydberg gate between rubidium (Rb) and cesium (Cs) atoms with fidelity F=0.975±0.002. The two-species atom array enables in-place quantum nondemolition (QND) qubit measurements which are a key capability for quantum error correction. We demonstrate this functionality with multiatom error syndrome measurements achieving QND measurement fidelities of F_{QND}=0.933(12) and 0.865(17) for two- and three-qubit plaquettes, respectively.