The coherence of qubits based on single Ca ions
Ferdinand Schmidt‐Kaler, S. Gulde, Mark Riebe, T. Deuschle, Axel Kreuter, Gavin P. T. Lancaster, Christoph Becher, Jürgen Eschner, H H ffner, R. Blatt · Journal of Physics B Atomic Molecular and Optical Physics · 2003
Two-level ionic systems, where quantum information is encoded in long-lived states (quantum bits, qubits), are discussed extensively for quantum information processing. We present a collection of measurements which characterize the stability of a qubit based on the S 1/2 – D 5/2 transition of single 40 Ca + ions in a linear Paul trap. We find coherence times of ≃ 1 ms, discuss the main technical limitations and outline possible improvements.