Midgap state requirements for optically active quantum defects

Xiong, Yihuang; Mathew, Milena; Griffin, Sinéad M; Sipahigil, Alp; Hautier, Geoffroy

doi:10.1088/2633-4356/ad1d38

Cited by 6 publications

(1 citation statement)

References 87 publications

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“…The positions of defect states in host materials strongly depend on the type of defects; some are localized at shallow levels, while others are localized at deep levels. ,− The electronic structure of any defect can be calculated with density functional theory (DFT). Although this calculation can reasonably predict the electronic structures, assigning such microscopic origins remains challenging due to excessive defect choices and similar properties of different defects.…”

Section: Introductionmentioning

confidence: 99%

The hBN Defects Database: A Theoretical Compilation of Color Centers in Hexagonal Boron Nitride

Cholsuk,

Zand,

Çakan

et al. 2024

J. Phys. Chem. C

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Color centers in hexagonal boron nitride (hBN) have become an intensively researched system due to their potential applications in quantum technologies. There has been a large variety of defects being fabricated, yet, for many of them, the atomic origin remains unclear. The direct imaging of the defect is technically very challenging, in particular since, in a diffractionlimited spot, there are many defects and then one has to identify the one that is optically active. Another approach is to compare the photophysical properties with theoretical simulations and identify which defect has a matching signature. It has been shown that a single property for this is insufficient and causes misassignments.Here, we publish a density functional theory-based searchable online database covering the electronic structure of hBN defects (257 triplet and 211 singlet configurations), as well as their photophysical fingerprint (excited state lifetime, quantum efficiency, transition dipole moment and orientation, polarization visibility, and many more). All data is open-source and publicly accessible at https://h-bn.info and can be downloaded. It is possible to enter the experimentally observed defect signature and the database will output possible candidates which can be narrowed down by entering as many observed properties as possible. The database will be continuously updated with more defects and new photophysical properties (which can also be specifically requested by any users).The database therefore allows one to reliably identify defects but also investigate which defects might be promising for magnetic field sensing or quantum memory applications.

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Section: Introductionmentioning

confidence: 99%

The hBN Defects Database: A Theoretical Compilation of Color Centers in Hexagonal Boron Nitride

Cholsuk,

Zand,

Çakan

et al. 2024

J. Phys. Chem. C

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Computationally Driven Discovery of T Center-like Quantum Defects in Silicon

Xiong,

Zheng,

McBride

et al. 2024

J. Am. Chem. Soc.

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Quantum technologies would benefit from the development of highperformance quantum defects acting as single-photon emitters or spin-photon interfaces. Finding such a quantum defect in silicon is especially appealing in view of its favorable spin bath and high processability. While some color centers in silicon have been emerging in quantum applications, there remains a need to search for and develop new high-performance quantum emitters. By searching a high-throughput computational database of more than 22,000 charged complex defects in silicon, we identify a series of defects formed by a group III element combined with carbon ((A−C) Si with A = B, Al, Ga, In, Tl) and substituting on a silicon site. These defects are analogous structurally, electronically, and chemically to the well-known T center in silicon ((C−C−H) Si ), and their optical properties are mainly driven by an unpaired electron on the carbon p orbital. They all emit in the telecom, and some of these color centers show improved properties compared to the T center in terms of computed radiative lifetime, emission efficiency, or smaller optical linewidth. The kinetic barrier computations and previous experimental evidence show that these T center-like defects can be formed through the capture of a diffusing carbon by a substitutional group III atom. We also show that the synthesis of hydrogenated T center-like defects followed by a dehydrogenation annealing step could facilitate the formation of these defects. Our work motivates further studies on the synthesis and control of this new family of quantum defects and demonstrates the use of high-throughput computational screening to discover new color center candidates.

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A substitutional quantum defect in WS2 discovered by high-throughput computational screening and fabricated by site-selective STM manipulation

Thomas,

Chen,

Xiong

et al. 2024

Nat Commun

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Point defects in two-dimensional materials are of key interest for quantum information science. However, the parameter space of possible defects is immense, making the identification of high-performance quantum defects very challenging. Here, we perform high-throughput (HT) first-principles computational screening to search for promising quantum defects within WS2, which present localized levels in the band gap that can lead to bright optical transitions in the visible or telecom regime. Our computed database spans more than 700 charged defects formed through substitution on the tungsten or sulfur site. We found that sulfur substitutions enable the most promising quantum defects. We computationally identify the neutral cobalt substitution to sulfur (Co$${}_{{{{{{{{\rm{S}}}}}}}}}^{0}$$ S 0 ) and fabricate it with scanning tunneling microscopy (STM). The Co$${}_{{{{{{{{\rm{S}}}}}}}}}^{0}$$ S 0 electronic structure measured by STM agrees with first principles and showcases an attractive quantum defect. Our work shows how HT computational screening and nanoscale synthesis routes can be combined to design promising quantum defects.

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Midgap state requirements for optically active quantum defects

Cited by 6 publications

References 87 publications

The hBN Defects Database: A Theoretical Compilation of Color Centers in Hexagonal Boron Nitride

The hBN Defects Database: A Theoretical Compilation of Color Centers in Hexagonal Boron Nitride

Computationally Driven Discovery of T Center-like Quantum Defects in Silicon

A substitutional quantum defect in WS2 discovered by high-throughput computational screening and fabricated by site-selective STM manipulation

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