High-Resolution Quantum Sensing with Shaped Control Pulses
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2017-12-28 |
| Journal | Physical Review Letters |
| Authors | Jonathan Zopes, Kento Sasaki, K. S. Cujia, J. M. Boss, Kai Chang |
| Institutions | ETH Zurich, Keio University |
| Citations | 35 |
| Analysis | Full AI Review Included |
Technical Analysis: High Resolution Quantum Sensing with Shaped Control Pulses
Section titled âTechnical Analysis: High Resolution Quantum Sensing with Shaped Control PulsesâThis document analyzes the research presented on enhancing timing and frequency resolution in quantum sensing, specifically using the Nitrogen Vacancy (NV) center in MPCVD diamond. The goal is to provide a technical summary and link experimental requirements directly to 6CCVDâs advanced diamond materials and engineering services, positioning 6CCVD as the premier supplier for replicating and extending this cutting-edge research.
Executive Summary
Section titled âExecutive Summaryâ- Novel Methodology: Demonstrated a simple, effective method using amplitude-shaped microwave control pulses (cosine-square envelope) to significantly enhance the timing resolution of dynamical decoupling (DD) spectroscopy.
- Resolution Breakthrough: Achieved an interpulse delay timing resolution of 0.6 ps, representing an improvement exceeding three orders of magnitude compared to the 2 ns limit imposed by standard hardware sampling.
- Sensor Platform: Utilized the electronic spin of a single Nitrogen Vacancy (NV) center embedded within a single crystal diamond (SCD) substrate, highlighting the materialâs superior coherence properties ($T_{2} = 535$ ”s).
- Performance Metrics: Implemented DD sequences involving up to 10,000 coherent $\pi$ pulses, enabling ultra-high spectral resolution, reducing the minimum frequency increment ($\delta f$) to 114 Hz.
- Applications Demonstrated: Successfully applied the enhanced resolution technique to clearly distinguish two AC magnetic field signals separated by only 3 kHz and to detect high-resolution Nuclear Magnetic Resonance (NMR) spectra of proximal 13C bath nuclei.
- Engineering Requirement: Replication and advancement of this work necessitate high-purity Single Crystal Diamond (SCD) combined with precision metalized structures (Coplanar Waveguides) for efficient high-frequency microwave delivery.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Achieved Timing Resolution ($\delta t$) | 0.6 | ps | Effective interpolation of interpulse delay ($\tau$) |
| Hardware Sampling Resolution ($t_{s}$) | 2 | ns | Limit of standard pulse generator without shaping |
| Qubit Resonance Frequency | ~ 2.2 | GHz | Target frequency for upconversion/spin control |
| Pulse Shape Used | Cosine-Square | N/A | Amplitude envelope for shaping control pulses |
| $\pi$ Pulse Duration ($t_{\pi}$) | 25 | ns | Full width at half maximum (FWHM) |
| Rabi Frequency | ~ 20 | MHz | Max rotation speed used for control pulses |
| Maximum Coherent Pulses (N) | 10,000 (Tested) | Pulses | Used for maximum filter narrowness/sensitivity |
| Minimum Frequency Increment ($\delta f$) | 114 | Hz | Achieved spectral resolution (corresponding to 0.6 ps $\delta t$) |
| Input AWG Vertical Resolution | 14 | bits | Essential for high-precision amplitude interpolation |
| Sensor Coherence Time ($T_{2}$) | 535 | ”s | Measured overall decoherence factor for the sequence |
| Target Nuclei Detected | 13C | N/A | NMR spectroscopy of nuclei proximal to the NV center |
Key Methodologies
Section titled âKey MethodologiesâThe core experiment hinges on using high-resolution arbitrary waveform generation coupled with precision microwave frequency manipulation and high-quality NV center material.
- Qubit Platform Setup: The solid-state spin of a single NV center in a diamond single crystal was utilized as the quantum sensor, initialized and read out using standard optical techniques.
- Waveform Generation: Control pulses were generated by an Arbitrary Waveform Generator (AWG) operating at 500 MS/s with 14 bits of vertical resolution.
- Pulse Shaping Algorithm: A cosine-square amplitude profile was calculated numerically (Matlab code detailed in Supplementary Information) to create a smooth pulse envelope duration $t_{\pi}$ of 25 ns.
- Frequency Upconversion: The resulting waveform envelope (centered at 100 MHz) was multiplied with a carrier sine wave and upconverted via analog IQ mixing using an external synthesizer to the NV centerâs spin resonance frequency (~ 2.2 GHz).
- Microwave Delivery: Microwave pulses were delivered to the NV center via an on-chip coplanar waveguide (CPW) structure fabricated directly onto the diamond substrate.
- Dynamical Decoupling (DD) Sequence: The shaped pulses were arranged in sequences (up to $N=10,000$) to perform DD spectroscopy, effectively creating a narrow-band frequency filter.
- Sensing Mechanism: Precise tuning of the interpulse delay $\tau$ was achieved by exploiting the high vertical amplitude resolution of the shaped pulse envelope, enabling time variations far smaller than the hardware sampling time $t_{s}$.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe achievement of 0.6 ps timing resolution in this quantum sensing application directly relies on the quality and engineering precision of the diamond substrate and its integrated structures. 6CCVD is uniquely positioned to supply the materials and fabrication services required to replicate or advance this research, offering customized solutions that eliminate reliance on commodity materials.
Applicable Materials
Section titled âApplicable MaterialsâTo replicate the $T_{2}$ coherence times and stability demonstrated (535 ”s), the highest quality diamond material is essential.
| Research Requirement | 6CCVD Material Solution | Detail & Specification |
|---|---|---|
| High Coherence Qubit Host | Optical Grade Single Crystal Diamond (SCD) | Ultra-high purity MPCVD growth minimizes decoherence from lattice defects and trace impurities (e.g., Nitrogen concentration < 1 ppb for NV formation). |
| Structural Support | SCD Substrates | Available in thicknesses from 0.1 ”m up to 500 ”m, allowing precise control over NV depth and device integration. |
Advanced Customization Potential
Section titled âAdvanced Customization PotentialâThe experiment utilized a coplanar waveguide (CPW) structure to deliver the ~2.2 GHz microwave pulses. 6CCVD offers full integration services for such requirements.
| Paperâs Requirement | 6CCVD Engineering Service | Capability Specification |
|---|---|---|
| Precision Microwave Delivery (CPW) | Custom Metalization | In-house deposition of standard stacks (e.g., Ti/Pt/Au, Ti/W/Cu) required for low-loss transmission lines directly onto the SCD surface. |
| Surface Quality for Film Deposition | Ultra-Polishing | SCD wafers polished to atomic flatness (Ra < 1 nm) ensures optimal adhesion and uniformity for high-quality CPW fabrication. |
| Custom Device Geometry | Laser Cutting & Shaping | Precision laser modification allows for custom geometries required for packaging, mounting, and integration with microwave setups (e.g., custom sizes up to 125mm PCD/SCD). |
| Scaling and Replication | Large Area MPCVD Diamond | Ability to produce plates/wafers up to 125 mm (PCD) for scaling up quantum sensor arrays or optimizing geometry for specific external field detection setups. |
Engineering Support for Quantum Sensing Projects
Section titled âEngineering Support for Quantum Sensing Projectsâ6CCVDâs in-house PhD engineering team possesses deep expertise in the requirements of solid-state quantum systems. We are prepared to assist researchers and technical engineers in optimizing material selection and device design for projects involving high-fidelity quantum control, such as high-resolution NMR or AC magnetometry based on NV centers.
We provide consultation on:
- Optimal nitrogen doping levels (P1 centers) for subsequent NV creation.
- Selecting appropriate metalization stacks to minimize signal loss at high frequencies.
- Determining the required thickness and polish specifications for integration with advanced microwave or optical systems.
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
We investigate the application of amplitude-shaped control pulses for enhancing the time and frequency resolution of multipulse quantum sensing sequences. Using the electronic spin of a single nitrogen-vacancy center in diamond and up to 10 000 coherent microwave pulses with a cosine square envelope, we demonstrate 0.6-ps timing resolution for the interpulse delay. This represents a refinement by over 3 orders of magnitude compared to the 2-ns hardware sampling. We apply the method for the detection of external ac magnetic fields and nuclear magnetic resonance signals of ^{13}C spins with high spectral resolution. Our method is simple to implement and especially useful for quantum applications that require fast phase gates, many control pulses, and high fidelity.