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6CCVD Research

Tailoring the Emission Wavelength of Color Centers in Hexagonal Boron Nitride for Quantum Applications

At a Glance

Section titled “At a Glance”
MetadataDetails
Publication Date2022-07-15
JournalNanomaterials
AuthorsChanaprom Cholsuk, Sujin Suwanna, Tobias Vogl
InstitutionsFraunhofer Institute for Applied Optics and Precision Engineering, Mahidol University
Citations35
AnalysisFull AI Review Included

Technical Documentation & Analysis: Tailoring Quantum Emitters in hBN

Section titled “Technical Documentation & Analysis: Tailoring Quantum Emitters in hBN”

Reference Paper: Tailoring the Emission Wavelength of Color Centers in Hexagonal Boron Nitride for Quantum Applications (arXiv:2207.08506v1)

Executive Summary

Section titled “Executive Summary”

This research utilizes advanced Density Functional Theory (DFT) to identify and engineer color centers in hexagonal Boron Nitride (hBN) for quantum technology applications. The findings directly support the need for high-quality solid-state qubit systems, a core offering of 6CCVD.

  • Comprehensive Defect Analysis: Spin-polarized DFT calculations (HSE06 functional) characterized the electronic band structures of 267 hBN defect complexes.
  • Radiative Emitter Identification: 92 defects were identified as promising radiative single-photon emitters (SPEs), primarily exhibiting transition energies between 1.6 and 2.6 eV.
  • Wavelength Tailoring Mechanism: The study theoretically demonstrated that bi-axial strain-tuning can precisely tailor the emission wavelength of hBN defects to match specific quantum technology targets.
  • Quantum System Compatibility: Identified hBN defects compatible with critical reference qubits, including color centers in diamond (NV, SiV, PbV, GeV) and silicon carbide (VSi), as well as telecom wavelengths (1330 nm, 1550 nm).
  • Solid-State Qubit Coupling: The work provides a crucial guide for fabricating hBN emitters that can efficiently couple to existing solid-state qubit systems, highlighting the need for high-quality host materials like MPCVD diamond.

Technical Specifications

Section titled “Technical Specifications”

The following hard data points were extracted from the computational methodology and results:

ParameterValueUnitContext
DFT Functional UsedHSE06N/AHybrid functional used for accurate band gap prediction.
Defects Investigated (Total)267N/AComplexes including Group III-VI, Transition Metals, and Multi-defects.
Radiative Defects Identified92N/ADefects meeting criteria for promising quantum emitters.
Pristine hBN Band Gap (Eg)5.99eVDirect electronic band gap calculated using HSE06.
Typical Transition Energy Range1.6 to 2.6eVRange containing the majority of fluorescent hBN defects.
Supercell Size7 x 7 x 1N/AUsed to exclude defect-defect interaction.
Vacuum Layer Thickness15ÅUsed to minimize van der Waals interaction.
Force Convergence Criterion< 0.01eV·Å-1Criterion for lattice structural optimization.
Total Energy Convergence10-4eVCriterion for total energy convergence.
Strain Required (SBVB to PbV)0.10%Bi-axial strain needed to match the 552 nm ZPL of PbV in diamond.
Telecom O-Band Match (ONSN)0.946 / 1310.2eV / nmTransition energy/wavelength match for long-distance communication.

Key Methodologies

Section titled “Key Methodologies”

The experimental approach relied heavily on rigorous computational modeling to predict material behavior, focusing on defect stability and optical activity.

  1. Density Functional Theory (DFT) Setup: All calculations were performed using spin-polarized DFT (QuantumATK S-2021.06) utilizing the Heyd-Scuseria-Ernzerhof (HSE06) functional to ensure accurate prediction of electronic band structures and band gaps.
  2. Defect Modeling: Point-like defects were created in the center of a 7 x 7 x 1 hBN supercell. A 15 Å vacuum layer was added to minimize interlayer van der Waals interactions.
  3. Structural Optimization: Lattice structural optimization was performed, allowing internal coordinates to relax until all forces were below 0.01 eV·Å-1 and total energy convergence reached 10-4 eV.
  4. Defect Classification: Defects were classified based on three criteria:
    • Electronic Transition Type: Determined by considering the imaginary part of the dielectric function (radiative transitions exhibit characteristic peaks).
    • Transition Energy: Estimated from the energy difference between the highest occupied and lowest unoccupied defect states.
    • Localization: Deep-level defects, well-isolated from band edges, were preferred for high room-temperature quantum efficiency.
  5. Strain-Tuning Simulation: Bi-axial strain was applied isotropically in the a and b directions using the built-in pressure function in QuantumATK. The geometry was relaxed again to calculate the resulting shift in the transition energy.
  6. Charge State Analysis: The study was expanded to include charged defects (±1) to identify new transition energies, noting that charging is not a suitable in-situ tuning mechanism but can generate new level structures.

6CCVD Solutions & Capabilities

Section titled “6CCVD Solutions & Capabilities”

This research validates the critical role of solid-state quantum emitters, particularly those in diamond and silicon carbide, as reference points for quantum network development. 6CCVD is uniquely positioned to supply the high-purity MPCVD diamond materials necessary to host these reference qubits and to support the advanced integration required for coupling hBN systems.

Research Requirement/Challenge6CCVD Solution & CapabilityTechnical Advantage
Reference Qubit Host MaterialThe paper focuses on matching hBN ZPLs to established color centers in Diamond (NV, SiV, PbV, GeV) and SiC (VSi).6CCVD provides Optical Grade Single Crystal Diamond (SCD) substrates grown via MPCVD, offering the ultra-low defect density and high purity essential for stable, high-coherence quantum emitters.
High-Efficiency Optical CouplingEfficient coupling requires precise alignment and ultra-smooth surfaces to minimize scattering losses, especially when integrating 2D materials like hBN.We offer SCD polishing services guaranteeing Ra < 1 nm and Inch-size PCD polishing down to Ra < 5 nm, providing the necessary surface quality for advanced integrated photonics.
Custom Device Fabrication & IntegrationQuantum devices often require custom geometries, laser cutting, and specific metal contacts for electrical or strain-tuning apparatus.6CCVD offers custom dimensions (plates/wafers up to 125mm PCD) and in-house metalization capabilities (Au, Pt, Pd, Ti, W, Cu) for fabricating complex quantum chips and strain mechanisms.
Advanced Defect EngineeringThe study highlights the need to control defect charge states and impurity types (e.g., Boron-Doped Diamond, BDD) for specific applications.We supply Boron-Doped Diamond (BDD) materials, crucial for creating specific electronic environments or p-type conductivity required in advanced quantum device architectures.
Material Robustness & ThicknessRobust solid-state qubits require thick, stable host materials for implantation and high-power operation.6CCVD provides SCD and PCD materials up to 500 ”m thick, with specialized substrates available up to 10 mm, ensuring mechanical stability and thermal management for high-performance quantum systems.
Engineering Support for Strain-Tuning ProjectsImplementing the theoretical strain-tuning mechanism requires expert knowledge in material mechanics and defect physics.6CCVD’s in-house PhD team offers specialized engineering support and consultation for projects involving material selection, defect creation protocols, and mechanical integration for similar strain-tuning quantum emitter projects.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

Optical quantum technologies promise to revolutionize today’s information processing and sensors. Crucial to many quantum applications are efficient sources of pure single photons. For a quantum emitter to be used in such application, or for different quantum systems to be coupled to each other, the optical emission wavelength of the quantum emitter needs to be tailored. Here, we use density functional theory to calculate and manipulate the transition energy of fluorescent defects in the two-dimensional material hexagonal boron nitride. Our calculations feature the HSE06 functional which allows us to accurately predict the electronic band structures of 267 different defects. Moreover, using strain-tuning we can tailor the optical transition energy of suitable quantum emitters to match precisely that of quantum technology applications. We therefore not only provide a guide to make emitters for a specific application, but also have a promising pathway of tailoring quantum emitters that can couple to other solid-state qubit systems such as color centers in diamond.

Tech Support

Section titled “Tech Support”

Original Source

Section titled “Original Source”

References

Section titled “References”
  1. 2002 - Quantum cryptography [Crossref]
  2. 2010 - Quantum computers [Crossref]
  3. 2011 - Advances in quantum metrology [Crossref]
  4. 2018 - Quantum internet: A vision for the road ahead [Crossref]
  5. 2017 - Satellite-to-ground quantum key distribution [Crossref]
  6. 2018 - Quantum technologies with optically interfaced solid-state spins [Crossref]
  7. 2009 - Maximal success probabilities of linear-optical quantum gates [Crossref]
  8. 2012 - Memory-enhanced noiseless cross-phase modulation [Crossref]
  9. 2001 - A One-Way Quantum Computer [Crossref]
  10. 2005 - Experimental one-way quantum computing [Crossref]

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