A First Principles Study of the Stark Shift Effect on the Zero-Phonon Line of the NV Center in Diamond

Quantum defects in semiconductors are pivotal for quantum information science applications due to their potential as spin-photon interfaces and single-photon emitters. However, the coupling between changes in the dipole moment upon electronic excitation and stray electric fields near the defect, known as the Stark shift, can cause significant spectral diffusion in the emitted photons, thus hindering their quantum applications. In this talk, I will use the nitrogen-vacancy (NV) center in diamond as a critical example to showcase our work employing first-principles calculations to revisit and refine the methodology for computing Stark shifts up to the second order. Utilizing a slab approach, we monitor the zero-phonon line (ZPL) shifts under applied electric fields using constrained density functional theory (DFT) and compare these results with those derived from the modern theory of polarization. I will discuss the methodological challenges associated with charged slabs and the issues arising from the modern theory of polarization approach. Our work not only highlights the complexity of simulating Stark shifts but also provides important insights into their effects on ZPL and spectral diffusion.