High-fidelity entanglement of 43Ca+ hyperfine clock states

@article{Kirchmair2009HighfidelityEO,
  title={High-fidelity entanglement of 43Ca+ hyperfine clock states},
  author={Gerhard Kirchmair and Jan Benhelm and Florian Zahringer and Rene Gerritsma and Christian F. Roos and Rainer Blatt},
  journal={Physical Review A},
  year={2009},
  volume={79},
  pages={020304}
}
In an experiment using the odd calcium isotope $^{43}\mathrm{Ca}^{+}$, we combine the merits of a high-fidelity entangling operation on an optical transition (optical qubit) with the long coherence times of two ``clock'' states in the hyperfine ground state (hyperfine qubit) by mapping between these two qubits. For state initialization, state detection, global qubit rotations, and mapping operations, errors smaller than 1% are achieved, whereas the entangling gate adds errors of 2.3%. Based on… 

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