Quantum Defects and Recombination in Two Dimensions*

When applying first-principles computational techniques to quantum defects in two-dimensional (2D) systems, care needs to be taken in handling the Coulomb interactions with the reduced dimensionality and stronger many-body interaction. We will show our recent progress on developing first-principles methods for charged defects in two-dimensional materials. We will show how to correctly handle reduced dimensionality on the defect formation energies and ionization energies from hybrid functionals and GW approximations, using quantum defects in hexagonal boron nitride as a test-bed system [1-2].

We will also discuss our recent development on recombination methods in low-dimensional quantum defects [3], demonstrating the effect of strain on radiative and phonon-assisted non-radiative lifetimes of defects in hexagonal boron nitride. We will show our recent work on discovery of new 2D quantum defects with strong exciton-defect coupling and fast intersystem crossing rate due to spin-orbit coupling[4]. Lastly, we will briefly show our recently developed methodology to compute spin-phonon relaxation rates from a first-principles density-matrix approach[5], which is necessary to realize quantum defects as spin qubits and sensors.

[1] T. J. Smart, F. Wu, M. Govoni, and Y. Ping, Phys. Rev. Materials 2, 124002 (2018).
[2] F. Wu, A. Galatas, R. Sundararaman, D. Rocca and Y. Ping, Phys. Rev. Materials 1, 071001 (R) (2017)
[3] F. Wu, T. J. Smart, J. Xu, and Y. Ping, Phys. Rev. B 100, 081407(R) (2019).
[4] T. J. Smart, K. Li, J. Xu and Y. Ping, under review, arXiv: 2009.02830 (2020).
[5] J. Xu, A. Habib, S. Kumar, F. Wu, R. Sundararaman, and Y. Ping, Nat. Commun. 11, 2780 (2020).