Orientation mapping of Rabi frequencies in a rare-earth molecular qudit

Abstract

Spin active molecules have been proposed for quantum computing, due to their unique advantages such as the possibility of having multiple eigenstates. Using pulse electron paramagnetic resonance, a Gd(III) complex was thoroughly investigated to demonstrate the protocol of harnessing the large spin quantum number of the rare-earth molecule and implementing a qudit. The desired anisotropy of the S = 7/2 system, which makes all spin transitions addressable with an X-band spectrometer, was quantitatively determined at 10 K with a set of crystal field parameters. The relatively long phase memory time, ca. 1 μs, of the oxygen-coordinated 4f spin was extended up to 16.8 μs using dynamic decoupling pulse sequences. An arbitrary superposition state between each adjacent level pair was achieved by Rabi cycles with a crystal sample positioned in both perpendicular and parallel directions. Finally, a more detailed orientation mapping of the Rabi frequencies, which govern the quantum phase gate operation time, was provided based on the spin Hamiltonian.