First-principles investigation of hyperfine interactions for nuclear spin entanglement in photo-excited fullerenes

TL;DR

This paper uses first-principles calculations to analyze hyperfine interactions in photo-excited fullerenes, aiming to facilitate nuclear spin entanglement for quantum information applications.

Contribution

It provides a pseudopotential method to accurately compute hyperfine coupling parameters in excited fullerenes and organic radicals, validated against experiments and all-electron calculations.

Findings

Hyperfine coupling parameters match experimental data.

Hyperfine interactions in triplet exciton states are characterized.

Results support nuclear spin entanglement proposals in chromophores.

Abstract

The study of hyperfine interactions in optically excited fullerenes has recently acquired importance within the context of nuclear spin entanglement for quantum information technology. We here report a first-principles pseudopotential study of the hyperfine coupling parameters of optically excited fullerene derivatives as well as small organic radicals. The calculations are performed within the gauge-invariant projector-augmented wave method [C. Pickard and F. Mauri, Phys. Rev. B. 63, 245101 (2001)]. In order to establish the accuracy of this methodology we compare our results with all-electron calculations and with experiment. In the case of fullerene derivatives we study the hyperfine coupling in the spin-triplet exciton state and compare our calculations with recent electron paramagnetic resonance measurements [M. Schaffry et al., Phys. Rev. Lett. 104, 200501 (2010)]. We discuss our results in light of a recent proposal for entangling remote nuclear spins in photo-excited chromophores.