  Photons and nuclear spins are two well-known building blocks in quantum
information science and technology. Establishing an efficient interface between
optical photons and nuclear spins, while highly desirable for hybridizing these
two quantum systems, is challenging because the interactions between nuclear
spins and the environment are usually weak in magnitude, and there is also a
formidable gap between nuclear spin frequencies and optical frequencies. In
this work, we propose an opto-nuclear quadrupolar (ONQ) effect, whereby optical
photons can be efficiently coupled to nuclear spins, similar to Raman
scattering. Compared to previous works, ancilla electron spins are not required
for the ONQ effect. This leads to advantages such as applicability in
defect-free nonmagnetic crystals and longer nuclear spin coherence time. In
addition, the frequency of the optical photons can be arbitrary, so they can be
fine-tuned to minimize the material heating and to match telecom wavelengths
for long-distance communications. Using perturbation theory and
first-principles calculations, we demonstrate that the ONQ effect is stronger
by several orders of magnitude than other nonlinear optical effects that could
couple to nuclear spins. Based on this rationale, we propose promising
applications of the ONQ effect, including quantum memory, quantum transduction,
and materials isotope spectroscopy. We also discuss issues relevant to the
experimental demonstration of the ONQ effect.
