Spin-Orbit Qubits of Rare-Earth-Metal Ions in Axially Symmetric Crystal Fields

Sylvain Bertaina (1) , J.H. H Shim (2) , S. Gambarelli (2) , B.Z. Z Malkin (3) , Bernard Barbara (4)

1 IM2NP - Institut des Matériaux, de Microélectronique et des Nanosciences de Provence
2 INAC - Institut Nanosciences et Cryogénie
3 KPFU - Kazan State University
4 NEEL - QuantECA - Circuits électroniques quantiques Alpes

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 $\mu$s) and the Rabi frequency $\Omega_R$ is anisotropic. Here, we present a study of the variations of $\Omega_R(\vec{H}_{0})$ with the magnitude and direction of the static magnetic field $\vec{H_{0}}$ for the odd $^{167}$Er isotope in a single crystal CaWO$_4$:Er$^{3+}$. The hyperfine interactions split the $\Omega_R(\vec{H}_{0})$ 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.

Mots clés: coherence; rare earth; quantum computer; qubit

Domaines: Electrons fortement corrélés [cond-mat.str-el]

Sylvain Bertaina, J.H. H Shim, S. Gambarelli, B.Z. Z Malkin, Bernard Barbara. Spin-Orbit Qubits of Rare-Earth-Metal Ions in Axially Symmetric Crystal Fields. Physical Review Letters, 2009, 103 (22), pp.226402. ⟨10.1103/PhysRevLett.103.226402⟩. ⟨hal-00435864v2⟩