Defect-engineering-based 2D single-photon emitters

Two-dimensional materials offer novel quantum electro-optical and magneto-optical properties. Defects play a crucial role in quantum photonics with hBN: on one hand, atomic defects in hBN behave as bright single-photon emitters operating at room temperature. On the other hand, defects also reduce phonon lifetimes which can be detrimental to infrared nanophotonic. Moreover, defect engineering is now becoming a common approach to localize charge and manipulate the optical excitations, determining their lifetimes, associated to the underlying spin and valley selectivity. Understanding the crystallographic structure, the effect of defect concentration, and their role in emission is thus critical for the design of 2D single-photon emitters based on defect engineering.

Defects are a complex problem because it requires exploring a large configurational space with sampling methods and characterizing the influence of defects on electro- and magneto-optical properties using first principles methods. Moreover, at finite temperatures, thermal effects, including lattice expansion, ripples, and entropic contributions, all influence the structures and stabilities of the defects. TIMES network combine expertise on first principles methods with molecular dynamics simulations to tackle this challenge.

Project: Real time exciton dynamics for efficient light emitters

The exciton relaxation is a complex phenomenon that involves different time scales and the coupling with several degrees of freedom. Excitons couple with phonons and in 2D materials exhibit a strong exciton spatial localization. The goal of the project is the formulation of a computational framework to describe exciton dynamics with emphasis on relaxation mechanisms.

More publications on exciton dynamics

First-principles study of luminescence in hexagonal boron nitride single layer: Exciton-phonon coupling and the role of substrate
P. Lechifflart, F. Paleari, D. Sangalli, and C. Attaccalite
Phys. Rev. Materials 7, 024006 (2023)

Exciton-exciton transitions involving strongly bound excitons: An ab initio approach
D. Sangalli, M. D’Alessandro, and C. Attaccalite
Physical Review B 107 (20), 205203

PI: Claudio Attaccalite
Aix-Marseille Université (France)

Project: Nonlinear optical responses in out-of-equilibrium systems

We will formulate an ab-initio approach to calculate nonlinear optical responses in out-of-equilibrium systems with focus on 2D materials, aiming to provide a predictive and quantitative description of both carrier dynamics and non linear effects. We will describe the sub-pico to picosecond timescale so to offer a detailed microscopic interpretation of experiments and to gain a better understanding of materials optoelectronics properties.

More publications on nonlinear optics

Floquet formulation of the dynamical Berry-phase approach to nonlinear optics in extended systems
I. M. Alliati, M. Grüning
Electronic Structure 5, 017001 (2023)

Second-harmonic generation in single-layer monochalcogenides: A response from first-principles real-time simulations
C. Attaccalite, M. Palummo, E. Cannuccia, M. Grüning
Physical Review Materials 3, 074003 (2023)

PI: Myrta Grüning
Queen’s University of Belfast (UK)

Project: Decoherence electron-ion effects in strongly perturbed finite electronic systems

We will study the dynamics of a finite electronic system irradiated by an intense fs laser field on a timescale that involves electronic dissipation via the coupling to the ionic motion (treated by non-adiabatic molecular dynamics). This coupling leads to energy flow between electrons and ions and to electronic dephasing and decoherence. We will address 2 fundamental processes in radiation chemistry and biology at the nanoscale: decoherence of charge migration and fragmentation dynamics.

MorE publications on quantum disSipative dynamics

The real-time TDDFT code “Quantum Dissipative Dynamics” on a GPU
P. M. Dinh, J. Heraud, A. Estaña, M. Vincendon, P. G. Reinhard, E. Suraud
Computer Physics Communications 295, 108947

Electrons as probes of dynamics in molecules and clusters: A contribution from Time Dependent Density Functional Theory
P. Wopperer, P. M. Dinh, P. G. Reinhard, E. Suraud
Physics Reports 562, 1-68

PI: Phuong Mai Dinh
Paul Sabatier University (France)

Project: Defects in 2D materials

Defects engineering is crucial for quantum photonics with two-dimensional (2D) materials and a deep understanding of the impact of defect stoichiometry, concentration and electro-optical behaviour is fundamental to tailor the single-photon emission process. This project will combine ab initio calculations of electronic and phononic spectrum with ab initio molecular dynamics simulations and Ehrenfest dynamics to deal with non-adiabatic effects on the electronic and optical properties of 2D materials in the presence of defects.


Position‐Controlled Functionalization of Vacancies in Silicon by Single‐Ion Implanted Germanium Atoms
S. Achilli, N. H. Le, G. Fratesi, N. Manini, G. Onida, M. Turchetti, G. Ferrari, T. Shinada, T. Tanii, E. Prati
Adv. Funct. Mater. 31 (21), 2011175 (2021)

Doping Graphene with Substitutional Mn
P.-C. Lin, R. Villareal, S. Achilli, H. Bana, M. N. Nair, A. Tejada, K. Verguts, S. De Gendt, M. Auge, H. Hofsäss, S. De Feyter, G. Di Santo, L. Petaccia, S. Brems, G. Fratesi, L. M. C. Pereira
ACS Nano 15 (3), 5449-5458 (2021)

PI: Simona Achilli
University of Milano (Italy)