Contrary to the well known spin qubits, rare-earth qubits are characterized by a strong influence of crystal field due to large spin-orbit coupling. At low temperature and in the presence of resonance microwaves, it is the magnetic moment of the crystal-field ground-state which nutates (for several μs) and the Rabi frequency ΩR is anisotropic. Here, we present a study of the variations of ΩR(H0) with the magnitude and direction of the static magnetic field H0 for the odd 167Er isotope in a single crystal CaWO4:Er3+. The hyperfine interactions split the ΩR(H0) curve into eight different curves which are fitted numerically and described analytically. These "spin-orbit qubits" should allow detailed studies of decoherence mechanisms which become relevant at high temperature and open new ways for qubit addressing using properly oriented magnetic fields.
@article{arxiv.0911.4818,
title = {Spin-Orbit Qubits of Rare-Earth-Metal Ions in Axially Symmetric Crystal Fields},
author = {Sylvain Bertaina and J. H. Shim and S. Gambarelli and B. Z. Malkin and B. Barbara},
journal= {arXiv preprint arXiv:0911.4818},
year = {2009}
}