Efficient and robust signal sensing by sequences of adiabatic chirped pulses
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2020-08-07 |
| Journal | Physical Review Research |
| Authors | Genko T. Genov, Yachel Ben-Shalom, Fedor Jelezko, Alex Retzker, Nir BarâGill |
| Institutions | Center for Integrated Quantum Science and Technology, Hebrew University of Jerusalem |
| Citations | 17 |
| Analysis | Full AI Review Included |
Technical Documentation & Analysis: Robust Quantum Sensing via RAP-XY8 in MPCVD Diamond
Section titled âTechnical Documentation & Analysis: Robust Quantum Sensing via RAP-XY8 in MPCVD DiamondâThis document analyzes the research paper, âEfficient and robust signal sensing by sequences of adiabatic chirped pulses,â focusing on the material requirements and experimental achievements related to Nitrogen-Vacancy (NV) centers in diamond. It highlights how 6CCVDâs advanced MPCVD diamond materials and customization capabilities can support and extend this critical quantum sensing research.
Executive Summary
Section titled âExecutive SummaryâThe research successfully demonstrates a highly robust and efficient method for AC quantum sensing using phased Rapid Adiabatic Passage (RAP) pulse sequences (RAP-XY8) in ensemble NV centers in diamond.
- Core Achievement: RAP-XY8 sequences significantly enhance the coherence time ($T_2$) and robustness of AC magnetometry compared to standard XY8 protocols.
- Performance Metric: Achieved a maximum $T_2$ of 1943 ± 231 ”s, demonstrating superior performance in systems with large inhomogeneous broadening ($2\pi \times 2.1$ MHz).
- Robustness: The RAP protocol proved robust against both driving field amplitude noise and low Rabi frequency conditions, where standard XY8 performance degraded significantly (up to 45% drop in $T_2$).
- Mechanism: Adiabatic chirped pulses act as a double filter for dynamical decoupling (DD), rectifying the signal and partially removing frequency noise.
- Sensitivity: Direct measurements showed a ~30% improvement in magnetic sensitivity ($\eta$) for RAP sequences over regular XY8 under optimized conditions.
- Material Requirement: The experiment relies on high-quality diamond substrates suitable for NV creation and microwave integration, confirming diamondâs role as the premier platform for robust quantum sensing.
Technical Specifications
Section titled âTechnical SpecificationsâThe following hard data points were extracted from the experimental results and simulations, highlighting the performance achieved using the RAP-XY8 protocol in NV diamond.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| SCD Coherence Time (RAP-XY8, Optimized) | 1943 ± 231 | ”s | High Rabi experiment |
| SCD Coherence Time (Standard XY8, Optimized) | 1811 ± 184 | ”s | High Rabi experiment |
| SCD Coherence Time (RAP-XY8, Low Rabi) | 1850 ± 389 | ”s | Robustness test, $\Omega_0 = 2\pi \times 1.7$ MHz |
| Inhomogeneous Broadening (FWHM) | $2\pi \times (2.1 \pm 0.1)$ | MHz | Experimental sample characteristic |
| Peak Rabi Frequency ($\Omega_0$) | $2\pi \times 5$ | MHz | High Rabi experiment |
| Target Chirp Range (R) | $2\pi \times 40$ | MHz | Optimized for High Rabi |
| Pulse Duration ($T_{pulse}$) | 11.4 | ”s | High Rabi experiment |
| Minimum Sensitivity ($\eta_{min,RAP}$) | 22 ± 4 | nT·Hz-1/2 | High Rabi with noise |
| Sensitivity Improvement (RAP vs XY8) | ~30 | % | Direct measurement |
| NV Density | ~10 | ppb | Standard-grade diamond sample |
| Static Bias Field | 332 | Gauss | Experimental setup |
Key Methodologies
Section titled âKey MethodologiesâThe experimental demonstration utilized advanced microwave control techniques on a diamond substrate hosting NV ensembles.
- Material Selection: A standard-grade diamond sample (Element Six) with an NV density of approximately 10 ppb was used as the sensing platform.
- Optical Initialization: NV centers were initialized to the $|0\rangle$ spin state via optical pumping using a 532 nm green laser source.
- Magnetic Environment: Experiments were conducted in a home-built confocal fluorescence microscope under a static magnetic bias field of 332 Gauss.
- Microwave Control Generation: Modulated microwave control fields, necessary for generating the complex chirped adiabatic pulses, were created using a high-speed Arbitrary Waveform Generator (AWG - Tektronix AWG70002A, 16 Gs).
- Pulse Sequence Implementation: The RAP-XY8 sequence was implemented using phased, adiabatic, chirped pulses based on the Allen-Eberly model, optimized experimentally for characteristic time ($T$) and chirp range ($R$).
- AC Field Sensing: An external AC magnetic signal was applied using a home-built coil driven by a function generator (Rigol 5252).
- Readout: Spin-dependent fluorescence (650-800 nm) was collected to measure the population transfer and determine coherence time ($T_2$) and magnetic sensitivity ($\eta$).
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThis research validates the use of advanced pulse sequences to overcome material limitations (inhomogeneous broadening, noise) inherent in standard diamond samples. 6CCVD provides the high-specification MPCVD diamond materials and customization services necessary to replicate, optimize, and scale this robust quantum sensing technology.
| Research Requirement/Challenge | 6CCVD Solution & Capability | Technical Advantage for Replication/Extension |
|---|---|---|
| High Coherence Time ($T_2$) | High Purity Single Crystal Diamond (SCD) | Our SCD features ultra-low nitrogen (< 1 ppb) and controlled NV creation, minimizing the spin bath noise that limits $T_2$. This enables coherence times significantly longer than the 1.94 ms reported, crucial for maximizing sensing precision ($\eta \propto 1/\sqrt{T_2}$). |
| Large Area Ensemble Sensing | Polycrystalline Diamond (PCD) Wafers | We offer custom PCD plates up to 125mm diameter. This is ideal for scaling up ensemble NV magnetometry and integrating large-area sensors into practical devices. |
| Robustness to Inhomogeneous Broadening | Custom NV Density Control | 6CCVD provides precise control over NV creation (via implantation or in-situ growth) to optimize NV density, allowing researchers to balance signal strength against broadening effects for specific applications. |
| Integrated Microwave Control | Custom Metalization Services | We offer internal metalization capabilities (Au, Pt, Pd, Ti, W, Cu). This is essential for fabricating high-fidelity on-chip microwave transmission lines (e.g., coplanar waveguides) directly onto the diamond surface, improving driving field homogeneity. |
| Optical Readout Efficiency | Ultra-Low Roughness Polishing | SCD polishing to Ra < 1 nm and inch-size PCD polishing to Ra < 5 nm ensures optimal surface quality for efficient optical coupling (532 nm excitation) and fluorescence collection (650-800 nm). |
| Substrate Dimensions | Custom Dimensions and Thicknesses | We supply SCD wafers from 0.1 ”m to 500 ”m thick, and substrates up to 10 mm thick, accommodating specific requirements for high-power MW delivery or thermal management. |
Engineering Support
Section titled âEngineering Supportâ6CCVDâs in-house PhD team specializes in MPCVD diamond growth and post-processing for quantum applications. We offer consultation services to assist researchers in selecting the optimal material specifications (e.g., SCD vs. PCD, specific NV doping levels, and surface preparation) required to replicate or extend this robust RAP-XY8 quantum sensing project.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
We propose a scheme for sensing of an oscillating field in systems with large inhomogeneous broadening and driving field variation by applying sequences of phased, adiabatic, chirped pulses. These act as a double filter for dynamical decoupling, where the adiabatic changes of the mixing angle during the pulses rectify the signal and partially remove frequency noise. The sudden changes between the pulses act as instantaneous Ï pulses in the adiabatic basis for additional noise suppression. We also use the pulsesâ phases to correct for other errors, e.g., due to nonadiabatic couplings. Our technique improves significantly the coherence time in comparison to standard XY8 dynamical decoupling in realistic simulations in NV centers with large inhomogeneous broadening. Beyond the theoretical proposal, we also present proof-of-principle experimental results for quantum sensing of an oscillating field in NV centers in diamond, demonstrating superior performance compared to the standard technique.