Fast, High-Fidelity Addressed Single-Qubit Gates Using Efficient Composite Pulse Sequences
A. D. Leu, Mario F. Gely, Marius Weber, M. C. Smith, D. P. Nadlinger, David Lucas
Abstract
We use electronic microwave control methods to implement addressed single-qubit gates with high speed and fidelity, for $^{43}{\mathrm{Ca}}^{+}$ hyperfine ``atomic clock'' qubits in a cryogenic (100 K) surface trap. For a single qubit, we benchmark an error of $1.5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ per Clifford gate (implemented using 600 ns $\ensuremath{\pi}/2$ pulses). For 2 qubits in the same trap zone (ion separation $5\text{ }\text{ }\mathrm{\ensuremath{\mu}}\mathrm{m}$), we use a spatial microwave field gradient, combined with an efficient four-pulse scheme, to implement independent addressed gates. Parallel randomized benchmarking on both qubits yields an average error $3.4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ per addressed $\ensuremath{\pi}/2$ gate. The scheme scales theoretically to larger numbers of qubits in a single register.