Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:2608.20837

First-principles design of main-group dimer defects in ZnO as candidate quantum defects

Taejoon Park, Erik Alfredo Perez, Shimin Zhang, Yuan Ping, Hosung Seo

cond-mat.mtrl-scicond-mat.mes-hallquant-phSubmitted Aug 21, 2026• Announced Aug 24, 2026
arXivHTMLPDF

Abstract

Zinc oxide (ZnO), a wide-band-gap semiconductor with mature growth techniques, is a promising host for optically active quantum spins. Yet, optically active quantum defects in ZnO remain largely unexplored. Here, we identify and characterize a family of double substitutional impurities in ZnO, formed by main-group donor-acceptor (DA) pairs, as candidates for optically active quantum defects. Using hybrid density functional theory (DFT), we systematically investigate double substitutional DA complexes and their defect physics, including electronic structure, thermodynamic stability, and optical properties. The proposed defects exhibit isolated defect states, strong spin localization on the acceptor site, and $C_{3v}$ symmetry. Importantly, the electronic structure of the DA pairs is largely determined by the atomic properties of their constituent atoms. We further examine their optical characteristics, including zero-phonon lines (ZPLs), radiative lifetimes, and nonradiative decay to assess their viability as color centers. Notably, among the dimers, (Si$_{Zn}$-B$_O$)$^+$ and (Ge$_{Zn}$-B$_O$)$^+$ exhibit visible optical transitions with sub-microsecond radiative lifetimes and robust charge states against optical ionization, while (Si$_{Zn}$-C$_O$)$^{2+}$ shows the smallest Huang-Rhys factor, approximately 5.6. Our results propose a new family of main-group donor-acceptor defects in ZnO as promising candidates for optically active spin defects.

Comments
13 pages, 5 figures

Related papers

Donor-acceptor pairs in wide-bandgap semiconductors for quantum technology applications

Anil Bilgin, Ian Hammock, Jeremy Estes +4 more

Abstract We propose a quantum science platform utilizing the dipole-dipole coupling between donor-acceptor pairs (DAPs) in wide bandgap semiconductors to realize optically controllable, long-range interactions between defects in the solid state. We carry out calculations based on density functional theory (DFT) to investigate the electronic structure and interactions of DAPs formed by various substitutional point-defects in diamond and silicon carbide (SiC). We determine the most stable charge states and evaluate zero phonon lines using constrained DFT and compare our results with those of simple donor-acceptor pair (DAP) models. We show that polarization differences between ground and excited states lead to unusually large electric dipole moments for several DAPs in diamond and SiC. We predict photoluminescence spectra for selected substitutional atoms and show that while B-N pairs in diamond are challenging to control due to their large electron-phonon coupling, DAPs in SiC, especially Al-N pairs, are suitable candidates to realize long-range optically controllable interactions.

arXiv:2305.05791•npj Computational Materials•Jan 6, 2024•19 citations

Identification of the I$_{10}$ Donor in ZnO as a Sn--Li Complex with Large Hyperfine Interaction

Xingyi Wang, Sai Mu, Jeong Rae Kim +6 more

Donor impurities in wide direct band gap semiconductors provide a promising platform for spin--photon quantum technologies by combining a donor spin qubit with optically addressable transitions. In ZnO, the shallow donor with the largest reported binding energy has long been associated with the I$_{10}$ bound exciton line, but its microscopic origin has remained unresolved. Here we demonstrate the controlled formation and identification of this donor as a Sn--Li complex through a combination of ion implantation, annealing, optical spectroscopy, and first-principles calculations. Resonant two-laser coherent population trapping measurements reveal an electron--$^{119}$Sn hyperfine interaction of $392 \pm 15$\,MHz, establishing a coupled electron--spin--1/2, nuclear--spin--1/2 system with one of the largest hyperfine couplings reported for shallow donors in semiconductors. Density functional theory calculations show that a nearest-neighbor Sn$_{\mathrm{Zn}}$--Li$_{\mathrm{Zn}}$ complex has favorable formation energetics, donor character with the electron localized on Sn, and an extrapolated hyperfine interaction consistent with experiment. The large donor binding energy and excited-state structure indicate enhanced thermal robustness of the optical transition relative to conventional group--III donors, while the strong hyperfine interaction enables fast electron--nuclear spin control and prospects for direct nuclear--spin--photon interfaces. We further observe efficient optically induced nuclear spin polarization, highlighting a path toward nuclear spin initialization. More broadly, our results reveal how a donor--acceptor complex can access previously unexplored regimes of shallow donor physics, extending the design space of quantum defects beyond isolated substitutional dopants.

quant-pharXiv:2603.05615•Mar 9, 2026

Electronic structure and magneto-optical properties of silicon-nitrogen-vacancy complexes in diamond

Marcin Roland Zemła, Kamil Czelej, Paulina Kamińska +2 more

The silicon-vacancy (SiV) and nitrogen-vacancy (NV) centers in diamond are commonly regarded as prototypical defects for solid-state quantum information processing. Here, we show that when silicon and nitrogen are simultaneously introduced into the diamond lattice, these defects can strongly interact and form larger complexes. Nitrogen atoms strongly bind to Si and SiV centers, and complex formation can occur. Using a combination of hybrid density functional theory and group theory, we analyze the electronic structure and provide various useful physical properties, such as hyperfine structure, quasilocal vibrational modes, and a zero-phonon line, to enable experimental identification of these complexes. We demonstrate that the presence of substitutional silicon adjacent to nitrogen significantly shifts the donor level toward the conduction band, resulting in an activation energy for the SiN center that is comparable to phosphorus. We also find that the neutral SiNV center is of particular interest due to its photon emission at $\ensuremath{\sim}1530\phantom{\rule{0.28em}{0ex}}\mathrm{nm}$, which falls within the $C$ band of telecom wavelengths and its paramagnetic nature. In addition, the optical transition associated with the ${\mathrm{SiNV}}^{0}$ color center exhibits very small electron-phonon coupling (Huang-Rhys factor = 0.78) resulting in high quantum efficiency (Debye-Waller factor = 46%) for single-photon emission. These features render this new center very attractive for a potential application in scalable quantum telecommunication networks.

arXiv:2006.11878•Physical review. B./Physical review. B•Sep 1, 2020•26 citations

Quantum embedding methods for correlated excited states of point defects: Case studies and challenges

Lukas Muechler, Danis I. Badrtdinov, Alexander Hampel +3 more

A quantitative description of the excited electronic states of point defects and impurities is crucial for understanding materials properties, and possible applications of defects in quantum technologies. This is a considerable challenge for computational methods, since Kohn-Sham density functional theory (DFT) is inherently a ground-state theory, while higher-level methods are often too computationally expensive for defect systems. Recently, embedding approaches have been applied that treat defect states with many-body methods, while using DFT to describe the bulk host material. We implement such an embedding method, based on Wannierization of defect orbitals and the constrained random-phase approximation approach, and perform systematic characterization of the method for three distinct systems with current technological relevance: a carbon dimer replacing a B and N pair in bulk hexagonal BN (${\mathrm{C}}_{\text{B}}{\mathrm{C}}_{\text{N}}$), the negatively charged nitrogen-vacancy center in diamond (${\mathrm{NV}}^{\ensuremath{-}}$), and an Fe impurity on the Al site in wurtzite AlN (${\text{Fe}}_{\text{Al}}$). In the context of these test-case defects, we demonstrate that crucial considerations of the methodology include convergence of the bulk screening of the active-space Coulomb interaction, the choice of exchange-correlation functional for the initial DFT calculation, and the treatment of the ``double-counting'' correction. For ${\mathrm{C}}_{\text{B}}{\mathrm{C}}_{\text{N}}$ we show that the embedding approach gives many-body states in agreement with analytical results on the Hubbard dimer model, which allows us to elucidate the effects of the DFT functional and double-counting correction. For the ${\mathrm{NV}}^{\ensuremath{-}}$ center, our method demonstrates good quantitative agreement with experiments for the zero-phonon line of the triplet-triplet transition. Finally, we illustrate challenges associated with this method for determining the energies and orderings of the complex spin multiplets in ${\text{Fe}}_{\text{Al}}$.

arXiv:2105.08705•Physical review. B./Physical review. B•Jun 6, 2022•64 citations

Chemical Control of Zero-Phonon Line Wavelength in Diamond Color Centers for Telecom-Band Emission

Chen Qiu, Han‐Pu Liang, Songyuan Geng +4 more

Solid-state color centers in diamond are promising candidates for quantum communication, yet the absence of intrinsic emitters operating in the telecom band has remained a fundamental bottleneck for scalable fiber-based quantum networks compatible with the existing optical fiber infrastructure. Here, by combining first-principles calculations with group-theoretical analysis, we establish a general chemical design rule that links the chemical nature of substitutional impurities to the zero-phonon line (ZPL) wavelengths of vacancy-impurity-vacancy centers in diamond. This framework shows that impurity atomic size and orbital energies act together to tune the ZPL. Specifically, heavy elements with fully filled d orbitals yielding shorter-wavelength emission, while lighter elements lacking occupied d orbitals, generate longer-wavelengths. Guided by this principle, we identify the negatively charged vacancy-magnesium-vacancy (MgV3−) center as an ideal telecom-band emitter at 1448 nm, exhibiting outstanding optical coherence, minimal electron−phonon coupling, and a remarkably high Debye−Waller factor of 94.1%. These results provide not only a long-sought candidate for fiber-compatible quantum emitters but also a transferable design paradigm for tailoring optical transitions in wide-bandgap hosts, paving the way for material discovery in solid-state quantum technologies.

Journal of the American Chemical Society•Mar 18, 2026•2 citations

Radiative electronic bound states in the continuum from defects in semiconductors

Seong Yun Hong, Liang Z. Tan, Ki Hoon Lee +2 more

Continuum-buried defect states in semiconductors are generally expected to be optically inactive due to their strong coupling to continuum bands. Here, we show that such defects can instead host radiative electronic bound states in the continuum (BICs), using the silicon G-center as a prototypical example. Hybrid-functional first-principles calculations with a Hubbard $U$ correction reveal that a localized defect state, initially buried below the valence band maximum (VBM) in the ground state, undergoes exchange-driven energy-level reordering under optical excitation and shifts above the VBM. This exchange-induced transition suppresses nonradiative decay and enables robust radiative emission. By computing temperature-dependent nonradiative lifetimes and comparing them with experimental photoluminescence (PL) lifetimes, we quantitatively reproduce the observed temperature dependence of the emission. These results uncover a stabilization mechanism for continuum-embedded defect states and establish electronic BICs as a general paradigm for designing defect-based optical systems, including quantum emitters and qubits.

cond-mat.mtrl-sciCross-listedarXiv:2605.26841•May 27, 2026
Zinc oxide (ZnO), a wide-band-gap semiconductor with mature growth techniques, is a promising host for optically active quantum spins. Yet, optically active quantum defects in ZnO remain largely unexplored. Here, we identify and characterize a family of double substitutional impurities in ZnO, formed by main-group donor-acceptor (DA) pairs, as candidates for optically active quantum defects. Using hybrid density functional theory (DFT), we systematically investigate double substitutional DA complexes and their defect physics, including electronic structure, thermodynamic stability, and optical properties. The proposed defects exhibit isolated defect states, strong spin localization on the acceptor site, and C3vC_{3v}C3v​ symmetry. Importantly, the electronic structure of the DA pairs is largely determined by the atomic properties of their constituent atoms. We further examine their optical characteristics, including zero-phonon lines (ZPLs), radiative lifetimes, and nonradiative decay to assess their viability as color centers. Notably, among the dimers, (SiZn_{Zn}Zn​-BO_OO​)+^++ and (GeZn_{Zn}Zn​-BO_OO​)+^++ exhibit visible optical transitions with sub-microsecond radiative lifetimes and robust charge states against optical ionization, while (SiZn_{Zn}Zn​-CO_OO​)2+^{2+}2+ shows the smallest Huang-Rhys factor, approximately 5.6. Our results propose a new family of main-group donor-acceptor defects in ZnO as promising candidates for optically active spin defects.
Abstract We propose a quantum science platform utilizing the dipole-dipole coupling between donor-acceptor pairs (DAPs) in wide bandgap semiconductors to realize optically controllable, long-range interactions between defects in the solid state. We carry out calculations based on density functional theory (DFT) to investigate the electronic structure and interactions of DAPs formed by various substitutional point-defects in diamond and silicon carbide (SiC). We determine the most stable charge states and evaluate zero phonon lines using constrained DFT and compare our results with those of simple donor-acceptor pair (DAP) models. We show that polarization differences between ground and excited states lead to unusually large electric dipole moments for several DAPs in diamond and SiC. We predict photoluminescence spectra for selected substitutional atoms and show that while B-N pairs in diamond are challenging to control due to their large electron-phonon coupling, DAPs in SiC, especially Al-N pairs, are suitable candidates to realize long-range optically controllable interactions.
Identification of the I10_{10}10​ Donor in ZnO as a Sn--Li Complex with Large Hyperfine Interaction
Donor impurities in wide direct band gap semiconductors provide a promising platform for spin--photon quantum technologies by combining a donor spin qubit with optically addressable transitions. In ZnO, the shallow donor with the largest reported binding energy has long been associated with the I10_{10}10​ bound exciton line, but its microscopic origin has remained unresolved. Here we demonstrate the controlled formation and identification of this donor as a Sn--Li complex through a combination of ion implantation, annealing, optical spectroscopy, and first-principles calculations. Resonant two-laser coherent population trapping measurements reveal an electron--119^{119}119Sn hyperfine interaction of 392±15392 \pm 15392±15\,MHz, establishing a coupled electron--spin--1/2, nuclear--spin--1/2 system with one of the largest hyperfine couplings reported for shallow donors in semiconductors. Density functional theory calculations show that a nearest-neighbor SnZn_{\mathrm{Zn}}Zn​--LiZn_{\mathrm{Zn}}Zn​ complex has favorable formation energetics, donor character with the electron localized on Sn, and an extrapolated hyperfine interaction consistent with experiment. The large donor binding energy and excited-state structure indicate enhanced thermal robustness of the optical transition relative to conventional group--III donors, while the strong hyperfine interaction enables fast electron--nuclear spin control and prospects for direct nuclear--spin--photon interfaces. We further observe efficient optically induced nuclear spin polarization, highlighting a path toward nuclear spin initialization. More broadly, our results reveal how a donor--acceptor complex can access previously unexplored regimes of shallow donor physics, extending the design space of quantum defects beyond isolated substitutional dopants.
The silicon-vacancy (SiV) and nitrogen-vacancy (NV) centers in diamond are commonly regarded as prototypical defects for solid-state quantum information processing. Here, we show that when silicon and nitrogen are simultaneously introduced into the diamond lattice, these defects can strongly interact and form larger complexes. Nitrogen atoms strongly bind to Si and SiV centers, and complex formation can occur. Using a combination of hybrid density functional theory and group theory, we analyze the electronic structure and provide various useful physical properties, such as hyperfine structure, quasilocal vibrational modes, and a zero-phonon line, to enable experimental identification of these complexes. We demonstrate that the presence of substitutional silicon adjacent to nitrogen significantly shifts the donor level toward the conduction band, resulting in an activation energy for the SiN center that is comparable to phosphorus. We also find that the neutral SiNV center is of particular interest due to its photon emission at $\ensuremath{\sim}1530\phantom{\rule{0.28em}{0ex}}\mathrm{nm}$, which falls within the CCC band of telecom wavelengths and its paramagnetic nature. In addition, the optical transition associated with the SiNV0{\mathrm{SiNV}}^{0}SiNV0 color center exhibits very small electron-phonon coupling (Huang-Rhys factor = 0.78) resulting in high quantum efficiency (Debye-Waller factor = 46%) for single-photon emission. These features render this new center very attractive for a potential application in scalable quantum telecommunication networks.
A quantitative description of the excited electronic states of point defects and impurities is crucial for understanding materials properties, and possible applications of defects in quantum technologies. This is a considerable challenge for computational methods, since Kohn-Sham density functional theory (DFT) is inherently a ground-state theory, while higher-level methods are often too computationally expensive for defect systems. Recently, embedding approaches have been applied that treat defect states with many-body methods, while using DFT to describe the bulk host material. We implement such an embedding method, based on Wannierization of defect orbitals and the constrained random-phase approximation approach, and perform systematic characterization of the method for three distinct systems with current technological relevance: a carbon dimer replacing a B and N pair in bulk hexagonal BN (CBCN{\mathrm{C}}_{\text{B}}{\mathrm{C}}_{\text{N}}CB​CN​), the negatively charged nitrogen-vacancy center in diamond (${\mathrm{NV}}^{\ensuremath{-}}$), and an Fe impurity on the Al site in wurtzite AlN (FeAl{\text{Fe}}_{\text{Al}}FeAl​). In the context of these test-case defects, we demonstrate that crucial considerations of the methodology include convergence of the bulk screening of the active-space Coulomb interaction, the choice of exchange-correlation functional for the initial DFT calculation, and the treatment of the ``double-counting'' correction. For CBCN{\mathrm{C}}_{\text{B}}{\mathrm{C}}_{\text{N}}CB​CN​ we show that the embedding approach gives many-body states in agreement with analytical results on the Hubbard dimer model, which allows us to elucidate the effects of the DFT functional and double-counting correction. For the ${\mathrm{NV}}^{\ensuremath{-}}$ center, our method demonstrates good quantitative agreement with experiments for the zero-phonon line of the triplet-triplet transition. Finally, we illustrate challenges associated with this method for determining the energies and orderings of the complex spin multiplets in FeAl{\text{Fe}}_{\text{Al}}FeAl​.
Solid-state color centers in diamond are promising candidates for quantum communication, yet the absence of intrinsic emitters operating in the telecom band has remained a fundamental bottleneck for scalable fiber-based quantum networks compatible with the existing optical fiber infrastructure. Here, by combining first-principles calculations with group-theoretical analysis, we establish a general chemical design rule that links the chemical nature of substitutional impurities to the zero-phonon line (ZPL) wavelengths of vacancy-impurity-vacancy centers in diamond. This framework shows that impurity atomic size and orbital energies act together to tune the ZPL. Specifically, heavy elements with fully filled d orbitals yielding shorter-wavelength emission, while lighter elements lacking occupied d orbitals, generate longer-wavelengths. Guided by this principle, we identify the negatively charged vacancy-magnesium-vacancy (MgV3−) center as an ideal telecom-band emitter at 1448 nm, exhibiting outstanding optical coherence, minimal electron−phonon coupling, and a remarkably high Debye−Waller factor of 94.1%. These results provide not only a long-sought candidate for fiber-compatible quantum emitters but also a transferable design paradigm for tailoring optical transitions in wide-bandgap hosts, paving the way for material discovery in solid-state quantum technologies.
Continuum-buried defect states in semiconductors are generally expected to be optically inactive due to their strong coupling to continuum bands. Here, we show that such defects can instead host radiative electronic bound states in the continuum (BICs), using the silicon G-center as a prototypical example. Hybrid-functional first-principles calculations with a Hubbard UUU correction reveal that a localized defect state, initially buried below the valence band maximum (VBM) in the ground state, undergoes exchange-driven energy-level reordering under optical excitation and shifts above the VBM. This exchange-induced transition suppresses nonradiative decay and enables robust radiative emission. By computing temperature-dependent nonradiative lifetimes and comparing them with experimental photoluminescence (PL) lifetimes, we quantitatively reproduce the observed temperature dependence of the emission. These results uncover a stabilization mechanism for continuum-embedded defect states and establish electronic BICs as a general paradigm for designing defect-based optical systems, including quantum emitters and qubits.