Fig. 1: Single-qubit characteristics of the 11-qubit atom processor.
a, Connectivity of nuclear spins (n1–n9) and electron spins (e1 and e2) through hyperfine and exchange coupling with energies in MHz. b, Scanning tunnelling micrograph of the processor core after hydrogen lithography showing the 4P register hosting n1–n4 and e1 (square) and the 5P register hosting n5–n9 and e2 (pentagon). The distance 13(1) nm (centre to centre) between the nuclear spin registers is atomically engineered to enable exchange coupling26,54. Scale bar, 10 nm. c, Exchange-coupled ESR spectrum of e2 as a function of voltage detuning ε with indications on the resonance frequencies corresponding to CROT and zCROT. d, Rabi oscillations along one period TRabi for all spins of the processor. We measure the spin-up probability of the nucleus P⇑ (electron P↑) as a function of the coherent NMR (ESR) drive duration. e, Phase coherence times measured for each spin through Ramsey (open symbols) and Hahn-echo (filled symbols) measurements. f, 1Q-RB results for each qubit showing average physical gate fidelities. SET, single-electron transistor.
