First Principles Computations of the Stark Shift Effect in a Defect-Bound-Exciton Color Center—The Case of the T Center in Silicon

Point defects in semiconductors such as the NV center in diamond have attracted a lot of attentions for their potential in quantum information science (QIS) applications. Of particular interests are the defects found in silicon owing to the exceptional level of maturity this host offers. The T center, a defect consisting of two carbons and a hydrogen sitting on a silicon site, is a prime candidate for QIS applications [1-3]. It exhibits spin-selective optical transitions in the telecom O-band as well as long electron and nuclear spin coherence times. The development and understanding of this defect require to evaluate the effect of an electric field on its optical emission (Stark shift). This is crucial for instance in controlling spectral diffusion in quantum network applications.
In this talk, I will present the results of our first-principles calculations on the T center. The T center is particularly challenging to study using ab initio methods due to the delocalized nature of the excited state, which consists of a bound exciton. This requires particular attention to the supercell size used and challenging convergence studies. We calculate the dipole moment change between the ground state and excited state using a methodology based on the modern theory of polarization that we recently used for the NV center in diamond [4]. We compare our results to the recent experimental measurements, provide insight into the process controlling the Stark shift and discuss the challenges associated with describing the physics of defect-bound exciton [5].

References:
[1] Dhaliah, Diana, et al. "First-principles study of the T center in silicon." Physical Review Materials 6.5 (2022): L053201.
[2] Bergeron, L., et al. "Silicon-integrated telecommunications photon-spin interface." PRX Quantum 1.2 (2020): 020301.
[3] Simmons, Stephanie. "Scalable fault-tolerant quantum technologies with silicon color centers." PRX Quantum 5.1 (2024): 010102.
[4] Alaerts, Louis, et al. "First-principles study of the Stark shift effect on the zero-phonon line of the NV center in diamond." Physical Review Materials 8.10 (2024): 106201.
[5] Clear, Chloe, et al. "Optical transition parameters of the silicon T centre." arXiv preprint arXiv:2405.07144 (2024).