Two-photon Interface of Nuclear Spins Based on the Opto-Nuclear Quadrupolar Effect

TL;DR

This paper introduces the opto-nuclear quadrupolar (ONQ) effect, a novel method for efficiently coupling optical photons to nuclear spins without ancilla electron spins, enabling advanced quantum information applications.

Contribution

The paper proposes the ONQ effect, a new mechanism for photon-nuclear spin interaction that is stronger than existing effects and applicable in defect-free nonmagnetic crystals.

Findings

ONQ effect is several orders of magnitude stronger than other nonlinear optical effects.

The effect does not require ancilla electron spins, broadening its applicability.

Potential applications include quantum memory, transduction, and isotope spectroscopy.

Abstract

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.