Recent advances in the <i>ab initio</i> theory of solid-state defect qubits

Gali, Ádám

doi:10.1515/nanoph-2022-0723

Cited by 21 publications

(6 citation statements)

References 164 publications

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“…Accordingly, we have demonstrated the luminescence mechanisms under different external stimulations in the single particle level summary (Fig. 6k-m) 51,52 . For the room temperature PL, the charge separation process is initiated by UV photoexcitation, where the electrons are excited from VB to CB, and the holes are left in the VB (Fig.…”

Section: Ev (476 Nm) Meanwhile the Electron Transfer From I Ga 2+ To ...mentioning

confidence: 68%

Dynamic multicolor emissions of multimodal phosphors by Mn2+ trace doping in self-activated CaGa4O7

Tang,

Cai,

Dou

et al. 2024

Nat Commun

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The manipulation of excitation modes and resultant emission colors in luminescent materials holds pivotal importance for encrypting information in anti-counterfeiting applications. Despite considerable achievements in multimodal and multicolor luminescent materials, existing options generally suffer from static monocolor emission under fixed external stimulation, rendering them vulnerability to replication. Achieving dynamic multimodal luminescence within a single material presents a promising yet challenging solution. Here, we report the development of a phosphor exhibiting dynamic multicolor photoluminescence (PL) and photo-thermo-mechanically responsive multimodal emissions through the incorporation of trace Mn2+ ions into a self-activated CaGa4O7 host. The resulting phosphor offers adjustable emission-color changing rates, controllable via re-excitation intervals and photoexcitation powers. Additionally, it demonstrates temperature-induced color reversal and anti-thermal-quenched emission, alongside reproducible elastic mechanoluminescence (ML) characterized by high mechanical durability. Theoretical calculations elucidate electron transfer pathways dominated by intrinsic interstitial defects and vacancies for dynamic multicolor emission. Mn2+ dopants serve a dual role in stabilizing nearby defects and introducing additional defect levels, enabling flexible multi-responsive luminescence. This developed phosphor facilitates evolutionary color/pattern displays in both temporal and spatial dimensions using readily available tools, offering significant promise for dynamic anticounterfeiting displays and multimode sensing applications.

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Section: Ev (476 Nm) Meanwhile the Electron Transfer From I Ga 2+ To ...mentioning

confidence: 68%

Dynamic multicolor emissions of multimodal phosphors by Mn2+ trace doping in self-activated CaGa4O7

Tang,

Cai,

Dou

et al. 2024

Nat Commun

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“…A series of 'quantum defects' have been identified for quantum information science (QIS) applications including color centers in diamond (e.g. the NV center, the Si split-vacancy) [1,5], SiC (silicon vacancy or the divacancy) [6], and hBN (boron vacancy, carbon dimer, and dangling bonds) [7][8][9] as well as the recently emerging defects in silicon such as the T center [10][11][12]. These defects constitute multi-qubit quantum registers based on electron and nuclear spins that can be optically initialized, measured and entangled over long distances [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Midgap state requirements for optically active quantum defects

Xiong,

Mathew,

Griffin

et al. 2024

Mater. Quantum. Technol.

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Optically active quantum defects play an important role in quantum sensing, computing and communication. The electronic structure and the single-particle energy levels of these quantum defects in the semiconducting host have been used to understand their opto-electronic properties. Optical excitations that are central for their initialization and readout are linked to transitions between occupied and unoccupied single-particle states. It is commonly assumed that only quantum defects introducing levels well within the band gap and far from the band edges are of interest for quantum technologies as they mimic an isolated atom embedded in the host. In this perspective, we contradict this common assumption and show that optically active defects with energy levels close to the band edges can display similar properties. We highlight quantum defects that are excited through transitions to or from a band-like level (bound exciton) such as the T center and SeSi + in silicon. We also present how defects such as the silicon divacancy in diamond can involve transitions between localized levels that are above the conduction band or below the valence band. Loosening the commonly assumed requirement on the electronic structure of quantum defects offers opportunities in quantum defects design and discovery especially in smaller band gap hosts such as silicon. We discuss the challenges in terms of operating temperature for photoluminescence or radiative lifetime in this regime. We also highlight how these alternative type of defects bring their own needs in terms of theoretical developments and fundamental understanding. This perspective clarifies the electronic structure requirement for quantum defects and will facilitate the identification and design of new color centers for quantum applications especially driven by first principles computations.

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“…Monino and Loos applied the method to atoms and molecules. Barker and Strubbe applied the method to molecules but also quantum defects in solids, adding to the available approaches for tackling these challenging systems [13]. (That work also pointed out the theoretical problems with using conventional GW calculations with SF-BSE.)…”

Section: Introductionmentioning

confidence: 99%

Computation of the expectation value of the spin operator S ^ 2

Barker,

Seshappan,

Strubbe

2024

Electron. Struct.

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Spin-flip methods applied to excited-state approaches like the Bethe-Salpeter Equation allow access to the excitation energies of open-shell systems, such as molecules and defects in solids. The eigenstates of these solutions, however, are generally not eigenstates of the spin operator S 2. Even for simple cases where the excitation vector is expected to be, for example, a triplet state, the value of 〈S 2〉 may be found to differ from 2.00; this difference is called "spin contamination." The expectation values 〈S 2〉 must be computed for each excitation vector, to assist with the characterization of the particular excitation and to determine the amount of spin contamination of the state. Our aim is to provide for the first time in the spin-flip methods literature a comprehensive resource on the derivation of the formulas for 〈S 2〉 as well as its computational implementation. After a brief discussion of the theory of the Spin-Flip Bethe-Salpeter Equation and some examples further illustrating the need for calculating 〈S 2〉, we present the derivation for the general equation for computing 〈S 2〉 with the eigenvectors from an SF-BSE calculation, how it is implemented in a Python script, and timing information on how this calculation scales with the size of the SF-BSE Hamiltonian.

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Recent advances in the ab initio theory of solid-state defect qubits

Cited by 21 publications

References 164 publications

Dynamic multicolor emissions of multimodal phosphors by Mn2+ trace doping in self-activated CaGa4O7

Dynamic multicolor emissions of multimodal phosphors by Mn2+ trace doping in self-activated CaGa4O7

Midgap state requirements for optically active quantum defects

Computation of the expectation value of the spin operator S ^ 2

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