| Metadata | Details |
|---|
| Publication Date | 2021-12-09 |
| Journal | Journal of Applied Physics |
| Authors | Duo Wang, Lei Liu, Houlong Zhuang |
| Institutions | Arizona State University |
| Citations | 8 |
| Analysis | Full AI Review Included |
- Novel Qubit Host Material: The diamond-like compound C3BN is proposed as a host for a novel solid-state spin qubit, specifically a negatively charged Boron vacancy (VB-) defect, which acts as an analog to the Nitrogen-Vacancy (NV) center in diamond.
- Fabrication Advantage: Unlike diamond NV centers, which require complex N implantation, the C3BN analog is formed simply by creating a Boron vacancy, potentially simplifying manufacturing processes for scalable quantum registers.
- Key Electronic Properties: DFT calculations using the SCAN functional confirm C3BN possesses a wide band gap (3.75 eV), negligible spin-orbit coupling (SOC), and an energetically stable negatively charged state (q = -1).
- Qubit Functionality: The VB- analog exhibits a paramagnetic triplet ground state (total spin S=1) and highly localized spin density, enabling manipulation via optical and magnetic methods, similar to the NV center.
- Telecommunication Compatibility: Two Zero-Phonon Line (ZPL) energies are predicted (1.104 eV and 1.504 eV), corresponding to wavelengths (1123 nm and 824 nm) significantly closer to the ideal telecommunication band, promising reduced optical loss in quantum networks.
- Quantum Register Potential: The computed hyperfine interactions are strong and comparable to those in diamond, suggesting C3BN can support multi-qubit registers necessary for quantum error correction and entanglement distillation.
| Parameter | Value | Unit | Context |
|---|
| Band Gap (Indirect) | 3.75 | eV | C3BN bulk (SCAN functional) |
| Ground State Spin | 1 | - | Paramagnetic triplet state (ms = 0, ±1) |
| Dielectric Constant (Δbb) | 5.75 | - | C3BN bulk (Highest component) |
| NV Analog Stability Range | 1.52 to 3.26 | eV | Fermi energy range where q = -1 state is most stable |
| Neutral Defect Formation Energy (q=0) | 6.82 | eV | C3BN (VB) |
| ZPL Energy (Case 1) | 1.104 | eV | Spin-conserving transition (a1(2) â ex) |
| ZPL Wavelength (Case 1) | 1123 | nm | Near O-band telecommunication window |
| ZPL Energy (Case 2) | 1.504 | eV | Spin-conserving transition (a1(2) â ey) |
| ZPL Wavelength (Case 2) | 824 | nm | Near C-band telecommunication window |
| Strongest Hyperfine Tensor (Azz, C1) | 263.850 | MHz | C3BN NV analog |
| C3BN Lattice Parameters | a = 5.669, b = 5.670, c = 3.595 | Angstrom | Optimized structure |
- Computational Platform: All calculations were performed using Density Functional Theory (DFT) implemented in the Vienna Ab initio Simulation Package (VASP).
- Exchange-Correlation Functional: The Strongly Constrained and Appropriately Normed (SCAN) semilocal density functional (meta-GGA) was used for exchange-correlation interactions, chosen for its accuracy in predicting band gaps and defect localization.
- Geometry Optimization: Initial structures were based on the optimized Si3AlP structure. Full optimization of lattice parameters and atomic coordinates was performed until the force threshold reached 0.01 eV.
- Supercell Simulation: The NV center analog (VB-) in C3BN was simulated using a large 2x2x3 supercell (240 atoms) to minimize finite-size effects, with one B atom removed and an extra electron added (q = -1).
- Dielectric Constant Calculation: The dielectric constant tensor was computed using Density Functional Perturbation Theory (DFPT) with the PBE functional on the SCAN-optimized geometry.
- Optical Transition Prediction: Zero-Phonon Line (ZPL) energies and potential energy curves were predicted using the constrained DFT method, following the Franck-Condon approximation, to model spin-conserving optical transitions.
- Hyperfine Structure Calculation: Hyperfine tensors, including Fermi contact and dipole-dipole coupling terms, were calculated using the SCAN functional to evaluate interactions between the qubit spin and surrounding nuclear spins (13C, 14N, 11B).
- Quantum Computing and Information Processing (QIP): C3BN serves as a promising, scalable host material for solid-state spin qubits, offering room-temperature operation capability.
- Quantum Communication Networks: The predicted ZPL wavelengths (1123 nm and 824 nm) are advantageous for long-distance quantum communication, as they align better with the low-loss windows of standard optical fibers (O-band and C-band).
- Scalable Semiconductor Device Fabrication: As a member of the A3XY family (containing Group IV elements like C, Si, Ge), C3BN is potentially compatible with mature semiconductor processing techniques (e.g., CVD, MBE), facilitating the integration and scaling of quantum devices.
- Quantum Sensing: Defect centers with highly localized spin densities and strong hyperfine interactions are ideal for high-resolution quantum sensing applications (e.g., magnetic field, temperature).
- Quantum Error Correction (QEC): The strong and controllable hyperfine interactions allow the surrounding nuclear spins (e.g., 13C, 11B) to be used as auxiliary qubits, forming a multi-qubit register necessary for implementing QEC protocols.
View Original Abstract
The nitrogen-vacancy (NV) center in diamond plays important roles in emerging quantum technologies. Currently available methods to fabricate the NV center often involve complex processes such as N implantation. By contrast, in a diamond-like compound C3BN, creating a boron (B) vacancy immediately leads to an NV-center analog. We use the strongly constrained and appropriately normed semilocal density functionalâthis functional leads to nearly the same zero-phonon line (ZPL) energy as the experiment and as obtained from the more time-consuming hybrid density functional calculationsâto explore the potential of this NV-center analog as a novel spin qubit for applications in quantum information processing. We show that the NV-center analog in C3BN possesses many similar properties to the NV center in diamond including a wide bandgap, weak spin-orbit coupling, an energetically stable negatively charged state, a highly localized spin density, a paramagnetic triplet ground state, and strong hyperfine interactions, which are the properties that make the NV center in diamond stand out as a suitable quantum bit (qubit). We also predict that the NV-center analog in C3BN exhibits two ZPL energies that correspond to longer wavelengths close to the ideal telecommunication band for quantum communications. C3BN studied here represents only one example of A3XY (A: group IV element; X/Y: group III/V elements) compounds. We expect many other compounds of this family to have similar NV-center analogs with a wide range of ZPL energies and functional properties, promising to be the new hosts of qubits for quantum technology applications. Furthermore, A3XY compounds often contain group IV elements such as silicon and germanium, so they are compatible with sophisticated semiconductor processing techniques. Our work opens up ample opportunities toward scalable qubit host materials and novel quantum devices.
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