Superresolution localization of nitrogen-vacancy centers in diamond with quantum-controlled photoswitching

At a Glance

Metadata	Details
Publication Date	2020-10-20
Journal	Physical review. A/Physical review, A
Authors	You Huang, Maosen Guo, M. Shen, Pei Yu, Mengqi Wang
Institutions	Hefei National Center for Physical Sciences at Nanoscale, CAS Key Laboratory of Urban Pollutant Conversion
Citations	4
Analysis	Full AI Review Included

Super-resolution NV Localization in Diamond: 6CCVD Technical Analysis

This document analyzes the requirements and achievements detailed in the research paper “Super-resolution Localization of Nitrogen Vacancy Centers in Diamond with Quantum Controlled Photoswitching” and maps them directly to 6CCVD’s high-purity MPCVD diamond solutions, positioning 6CCVD as the ideal material supplier for replicating and advancing this quantum sensing technology.

Executive Summary

This research demonstrates a novel method for achieving super-resolution localization of Nitrogen Vacancy (NV) centers in diamond, critical for scalable quantum computing and high-sensitivity sensing.

Core Achievement: Super-resolution localization of NV centers using quantum phase encoding based on pulsed Magnetic Field Gradient (MFG).
Localization Accuracy: Achieved localization accuracy better than 1.4 nm under a scanning confocal microscope.
Ultimate Resolution: Demonstrated an ultimate photoswitching resolution of 0.15 nm, significantly surpassing conventional optical methods (> 10 nm).
Material Requirement: The method relies on ultra-pure Single Crystal Diamond (SCD) to ensure long spin decoherence times (T₂ > 200 µs) necessary for coherent quantum control.
Method Advantage: The technique avoids the stringent requirements for high laser power or high MFG typically needed in other super-resolution methods (e.g., STED or high DC MFG encoding).
Scalability: The approach is suitable for subnanometer scale addressing and control of qubits based on multiple coupled defect spins, paving the way for low-power quantum chip integration.
6CCVD Value: 6CCVD provides the necessary high-purity SCD substrates, custom dimensions, and integrated metalization services required to fabricate the complex on-chip structures (microwires) used in this experiment.

Technical Specifications

The following hard data points were extracted from the research paper detailing the experimental parameters and results:

Parameter	Value	Unit	Context
Localization Accuracy	< 1.4	nm	Achieved via confocal scanning and Gaussian fitting.
Ultimate Photoswitching Resolution	0.15	nm	Minimum resolution achieved by gradient quantum control.
Resolved NV Separation Distance	266.0	nm	Distance between two neighboring NV centers (NV C & D).
Diamond Material Type	Ultra-pure SCD	N/A	Required for long decoherence time.
Diamond Thickness Used	200	µm	Substrate thickness.
NV Center Generation Method	¹⁴N Ion Implantation	N/A	Followed by high-temperature annealing.
Implantation Energy	70	keV	Energy used for ¹⁴N ions.
Implantation Dose	2 x 10⁹	cm^-2	Low dose for isolated centers.
Annealing Temperature	1000	°C	Post-implantation thermal treatment.
Static Magnetic Field (B_z)	9.37	mT	Applied along the NV [111] axis.
Zero-Field Splitting (D_GS)	2.87	GHz	Characteristic of the negatively charged NV center.
Microwire Thickness	200	nm	Thickness of fabricated gold (Au) microwires.

Key Methodologies

The experiment relies on precise material preparation and sophisticated quantum control sequences:

Substrate Selection: Ultra-pure Single Crystal Diamond (SCD) was selected to maximize the NV center decoherence time (T₂ > 200 µs), essential for coherent quantum phase encoding.
NV Center Creation: NV centers were generated by implanting 70 keV ¹⁴N ions at a low dose (2 x 10⁹ cm^-2) into the SCD, followed by high-temperature (1000 °C) and high-vacuum (10^-6 Pa) annealing.
On-Chip Structure Fabrication: Gold (Au) microwires (20 µm x 200 nm and 1 µm x 200 nm) were fabricated onto the diamond surface to generate the pulsed Magnetic Field Gradient (MFG).
Quantum State Initialization: NV centers were optically pumped using a 532 nm laser to initialize the spin state to |0> (fluorescence bright, “ON”).
Coherent Manipulation: Spin states were coherently manipulated using a spin echo pulse sequence incorporating pulsed Microwave (MW) magnetic fields and pulsed MFG.
Photoswitching and Localization: By varying the current amplitude in the microwire, position-dependent quantum phases were accumulated, allowing spatially selective manipulation of neighboring NV centers to alternate between “ON” (|0>) and “OFF” (|1>) states.
Super-resolution Imaging: Confocal scanning and subsequent subtraction of fluorescence maps (e.g., F_{|0>⊗|0>} - F_{|1>⊗|0>}) revealed the position of individual NV centers, achieving sub-nanometer localization via Gaussian fitting.

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to supply the high-specification diamond materials and fabrication services required to replicate and advance this super-resolution quantum technology.

Research Requirement	6CCVD Solution & Capability	Technical Advantage
Material Purity: Ultra-pure SCD for T₂ > 200 µs	Optical Grade Single Crystal Diamond (SCD)	Our high-purity MPCVD SCD features extremely low native nitrogen concentration (< 1 ppb), ensuring maximum spin coherence time (T₂) necessary for complex quantum phase encoding protocols.
Dimensions: 200 µm thickness	Custom Thickness SCD Plates	6CCVD supplies SCD plates with precise thickness control, ranging from 0.1 µm up to 500 µm, allowing researchers to optimize implantation depth and thermal management.
Substrate Size: Inch-scale wafers for integration	Large Area SCD/PCD Wafers	We offer plates/wafers up to 125 mm (PCD) and large-area SCD, facilitating the integration of these super-resolution techniques into scalable quantum chips.
Surface Structure: Gold (Au) Microwires (200 nm thick)	Internal Metalization Services (Au, Ti, Pt)	We offer in-house deposition of metals (Au, Ti, Pt, Pd, W, Cu) with precise thickness control (e.g., 200 nm), enabling direct fabrication of the required gradient microwires and coplanar waveguides on the diamond surface.
Surface Quality: Ra < 1 nm for lithography	Precision Polishing Services	Our SCD material is polished to an ultra-low surface roughness (Ra < 1 nm), which is critical for high-resolution lithography required to define the nanometer-scale microwire structures.
Post-Processing: Implantation and Annealing	Engineering Consultation & Recipe Optimization	6CCVD’s in-house PhD team can assist researchers in selecting the optimal SCD material grade and advising on post-growth processing parameters (e.g., annealing temperature and duration) necessary for high-yield, shallow NV center generation.

Applicable Materials

To replicate the long coherence times and high spatial resolution demonstrated in this paper, the required material is Optical Grade Single Crystal Diamond (SCD). This material ensures minimal background defects, maximizing the T₂ time of the implanted NV centers.

Customization Potential

The experiment utilized specific dimensions (200 µm thickness) and required the fabrication of gold microwires. 6CCVD offers:

Custom Dimensions: SCD plates can be supplied in thicknesses from 0.1 µm to 500 µm, and custom shapes can be achieved via laser cutting.
Integrated Metalization: We provide turnkey solutions for depositing the required Au/Ti/Pt metal stacks directly onto the diamond surface, streamlining the fabrication process for on-chip quantum control elements.

Engineering Support

6CCVD’s team of expert material scientists and engineers specializes in diamond for quantum applications. We offer comprehensive support for projects involving NV Center Quantum Sensing and Qubit Control, including material selection, surface preparation, and optimization for ion implantation and annealing recipes.

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

View Original Abstract

We demonstrate the super-resolution localization of the nitrogen vacancy\ncenters in diamond by a novel fluorescence photoswitching technique based on\ncoherent quantum control. The photoswitching is realized by the quantum phase\nencoding based on pulsed magnetic field gradient. Then we perform\nsuper-resolution imaging and achieve a localizing accuracy better than 1.4 nm\nunder a scanning confocal microscope. Finally, we show that the quantum phase\nencoding plays a dominant role on the resolution, and a resolution of 0.15 nm\nis achievable under our current experimental condition. This method can be\napplied in subnanometer scale addressing and control of qubits based on\nmultiple coupled defect spins.\n

Tech Support

Original Source

DOI: https://doi.org/10.1103/physreva.102.040601