Harnessing the power of quantum systems based on spin magnetic resonance - from ensembles to single spins
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2016-12-27 |
| Journal | Advances in Physics X |
| Authors | Xing Rong, Dawei Lu, Xi Kong, Jianpei Geng, Ya Wang |
| Institutions | University of Science and Technology of China, University of Waterloo |
| Citations | 12 |
| Analysis | Full AI Review Included |
Technical Documentation & Prospectus: MPCVD Diamond for Quantum Systems
Section titled âTechnical Documentation & Prospectus: MPCVD Diamond for Quantum SystemsâExecutive Summary
Section titled âExecutive SummaryâThe reviewed research highlights Single Crystal Diamond (SCD) containing Nitrogen Vacancy (NV) centers as the leading solid-state platform for advanced spin-based quantum computing and nanoscale sensing applications, demonstrating exceptional coherence control and high-fidelity gate operations.
- Platform Validation: NV centers in diamond are confirmed as high-performance hybrid electron-nuclear spin systems, enabling quantum memory and rapid quantum gate operations (Gigahertz speed).
- Coherence Enhancement: Implementation of advanced Dynamical Decoupling (DD) sequences (UDD/PDD) significantly prolonged electron spin coherence time (T2) from T2* â 135 ”s (naive pulse) up to TDCG â 690 ”s.
- High-Fidelity Gates: Utilizing sequences like BB1inC achieved an average single-qubit gate fidelity (Fa) of 0.999952(6) and CNOT gate fidelity of 0.9920(1) on the NV system.
- Nanoscale Sensing: NV center magnetometry demonstrates single molecule electron spin resonance (ESR) sensitivity down to 4 nTHz-1/2, crucial for molecular-scale imaging (NMR/ESR).
- Material Requirement: Achieving these performance metrics relies critically on ultra-low defect density and isotopically controlled (typically 12C purified) SCD substrates to minimize the decohering nuclear spin bath (e.g., 13C).
- 6CCVD Value: 6CCVD delivers the requisite Optical Grade, Ultra-Pure SCD wafers, available with customizable isotopic purity and industry-leading surface preparation (Ra < 1 nm), enabling the next generation of QIP and sensing devices.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Electron Spin Coherence (T2*) | 135 ± 10 | ”s | Measured with naive pulses (NV center in SCD) |
| Electron Spin Coherence (TDCG) | 690 ± 40 | ”s | Measured with 5-piece SUPCODE DD pulses |
| Spin-Locking Limit (T1Ï) | 660 ± 80 | ”s | Coherence saturation limit (independent measurement) |
| Single-Qubit Gate Fidelity (Fa) | 0.999952 ± 0.000006 | Dimensionless | Achieved using BB1inC pulse sequence (10 MHz control) |
| Two-Qubit CNOT Gate Fidelity | 0.9920 ± 0.0001 | Dimensionless | Achieved on electron spin and 14N nuclear spin register |
| Control Field Strength (Ï1) | 1, 10 | MHz | Microwave control field strength used in gate optimization |
| Static Magnetic Field (B0) | 513 | G | Applied along NV symmetry axis for 14N polarization |
| Nanomagnetometer Sensitivity | 4 | nTHz-1/2 | Achieved using higher-order DD sequences (Section 4.1) |
| Nuclear Spin Coherence (T2n) | 30 | ”s | Measured (Compared to T2e â 0.2 ”s without DD) |
Key Methodologies
Section titled âKey MethodologiesâThe research relies on precise manipulation and protection of spin coherence within the solid-state diamond matrix using advanced magnetic resonance techniques:
- Qubit System: Utilization of the electron spin (ms = 0 and ms = ±1 triplet states) and neighboring nuclear spins (e.g., 14N, 13C) of the NV center in Single Crystal Diamond (SCD) as hybrid qubits.
- Initialization and Readout: Optical pumping via 532 nm laser excitation, coupled with fluorescence detection for spin-state selective readout (Optically Detected Magnetic Resonance, ODMR).
- Spin Control: Manipulation using high-frequency MW and RF pulses for fast quantum gate operations. MW control of the electron spin enables indirect control and acceleration of slow nuclear spin gates via hyperfine coupling.
- Error Suppression (Decoherence): Application of Dynamical Decoupling (DD) sequences (e.g., PDD, UDD, XY8-N) to decouple the electron spin qubit from the noisy nuclear spin bath environment (spectral diffusion).
- Fault-Tolerant Gates: Implementation of optimized pulse sequences (GRAPE, SUPCODE, BB1inC) designed to simultaneously suppress errors arising from environmental decoherence (ÎŽ) and control field instability (Ï1).
- Nanoscale Sensing: Use of Ramsey and Hahn-echo interferometry sequences, combined with DD, to selectively detect and characterize DC and AC magnetic fields generated by external spin ensembles (nanoscale NMR and ESR).
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & Capabilitiesâ6CCVD provides the specialized MPCVD diamond materials essential for replicating and advancing the high-performance quantum systems detailed in this research. Success in NV-based QIP and sensing is fundamentally dependent on diamond quality, purity, and surface precision.
Applicable Materials for Quantum Applications
Section titled âApplicable Materials for Quantum Applicationsâ| Application Need (Per Paper) | 6CCVD Material Recommendation | Rationale |
|---|---|---|
| High Coherence / Low Decoherence | Optical Grade SCD (Low N) | Ultra-low concentration of nitrogen (<100 ppb) and other paramagnetic defects ensures minimal environmental noise (HB). |
| Nuclear Spin Bath Mitigation | Isotopic Purity SCD (12C > 99.999%) | Minimizes indigenous 13C concentration, which is the primary source of electron spin dephasing (T2* limitation), extending coherence times crucial for QIP. |
| Hybrid Spin Systems (NV Creation) | [111] or [100] Oriented SCD | Precise crystal orientation is required for controlled NV center creation via ion implantation (e.g., shallow NV centers for surface sensing). |
| Nanoscale Device Integration | High Purity PCD / SCD Substrates | Plates/wafers available up to 125 mm (PCD) and substrates up to 10 mm thickness, providing scalable platforms for large-array quantum architectures. |
Customization Potential to Accelerate Research
Section titled âCustomization Potential to Accelerate ResearchâTo fully realize the potential of NV-center based quantum devices, 6CCVD offers end-to-end material customization and processing, directly addressing the requirements for complex hybrid systems:
- Precision Polishing (Ra < 1 nm): The surface quality of SCD is critical for creating stable, shallow NV centers, especially for nanoscale NMR and ESR where proximity to surface spins is necessary. 6CCVD guarantees Ra < 1 nm on SCD wafers.
- Custom Dimensions and Orientation: We supply custom-dimension plates and wafers up to 125 mm, ensuring compatibility with standard cleanroom and optical setups, including customized crystal orientations beyond standard [100].
- Integrated Metalization Services: NV-based experiments often require high-quality microwave (MW) and radio-frequency (RF) circuits for spin manipulation. 6CCVD provides in-house metalization capabilities, including Au, Pt, Pd, Ti, W, and Cu, allowing for direct integration of microwave waveguides and electrodes onto the diamond surface.
- Laser Micro-Processing: Complex quantum circuits or sample geometries may require precise structuring. We offer laser cutting and micro-machining services for fine patterning and specialized edge treatment.
Engineering Support
Section titled âEngineering Supportâ6CCVD employs an in-house team of expert PhD material scientists and technical engineers. We offer specialized consultation to researchers and developers working on similar projects, including:
- Defect Engineering Consultation: Assistance in selecting the optimal SCD substrate (purity, isotopic composition, crystallographic orientation) best suited for highly coherent NV center creation (via implantation or in-situ growth).
- Process Optimization: Guidance on material handling, cleaning protocols, and surface termination necessary for achieving high-fidelity gate operation and long-lived quantum memories.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
Quantum computation provides great speedup over its classical counterpart for certain tasks. Spin system is one of the most important candidates to realize quantum computations. The initialization, readout and quantum gate operations of spin-qubits can be accomplished by advanced spin resonance techniques, which include nuclear magnetic resonance, electron paramagnetic resonance and optically detected magnetic resonance. This review aims to summarize recent experimental progresses in spin-based quantum computing. Preserving quantum states, precise quantum operations, quantum algorithms and quantum simulations on spin systems are reviewed. The fast improvement of quantum technology motivated by quantum computations results in recent progress in spin magnetic resonance in nanoscale. This review also introduces the achievements in nanoscale magnetic resonance with Nitrogen vacancy centers in diamonds.