Mixed-signal data acquisition system for optically detected magnetic resonance of solid-state spins

At a Glance

Metadata	Details
Publication Date	2021-11-01
Journal	Review of Scientific Instruments
Authors	Feifei Zhou, Shupei Song, Yuxuan Deng, Ting Zhang, Bing Chen
Institutions	Hefei University of Technology
Citations	10
Analysis	Full AI Review Included

Technical Documentation & Analysis: Mixed-Signal DAQ for NV Center ODMR

Executive Summary

This documentation analyzes the reported mixed-signal Data Acquisition (DAQ) system designed for Optically Detected Magnetic Resonance (ODMR) experiments on solid-state spins, specifically Nitrogen-Vacancy (NV) centers in diamond.

Core Achievement: Successful implementation of a high-speed, mixed-signal DAQ system based on a Xilinx Zynq FPGA for synchronized acquisition and processing of analog (photodetector) and digital (APD) signals.
Performance Metrics: The system operates at a high clock rate, supporting sampling speeds up to 125 MSPS (Million Samples Per Second) with 14-bit resolution.
Synchronization Capability: Achieved precise hardware synchronization between analog and digital channels, essential for complex quantum control sequences.
Advanced Functionality: Demonstrated advanced quantum metrology techniques, including general-purpose cw-ODMR, Rabi oscillation, and synchronized Lock-in detection of single NV centers.
Material Relevance: The entire experimental platform relies on high-quality, low-strain Single Crystal Diamond (SCD) substrates for hosting stable NV centers and integrating microwave antennas.
6CCVD Value Proposition: 6CCVD provides the necessary high-purity, optical-grade SCD substrates, custom dimensions, and specialized metalization required to replicate and advance this high-performance quantum sensing platform.

Technical Specifications

The following hard data points were extracted from the research paper detailing the performance and parameters of the mixed-signal DAQ system and the NV center experiment.

Parameter	Value	Unit	Context
Maximum Clock Rate	125	MHz	DAQ system operation
Maximum Sampling Rate	125	MSPS	Analog-to-Digital Converter (ADC)
ADC Resolution	14	bits	LTC2145CUP-14
Analog Channels (Total)	4	Channels	2 Inputs, 2 Outputs
Digital Channels (Optional)	16	Channels	Digital Inputs/Outputs
Time Resolution (PWM)	8	ns	Pulse Width Modulation (MSG output)
RF Signal Bandwidth	0 to near 50	MHz	-3 dB point at 49.57 MHz
RF Signal Amplitude (Max)	2	Vpp	Corresponds to ~10 dBm into 50 Ω load
NV Excitation Laser	532	nm	Green laser source
NV Fluorescence Range	637 to 800	nm	Optical readout
Static Magnetic Field	~52	mT	Used for ¹⁴N nuclear spin polarization
Temperature Calibration Range	30 to 60	°C	Environmental temperature testing
Bias Noise (Max, 60 °C)	1.275	mV	Average bias noise of analog channels

Key Methodologies

The DAQ system implementation focused on high-speed, synchronized mixed-signal processing enabled by a robust FPGA architecture.

FPGA Architecture: The system is built upon a Xilinx Zynq XC7Z010 FPGA, leveraging both the Programmable Logic (PL) for high-speed processing and the Processing System (PS) (ARM Cortex A9) for control and communication.
Mixed-Signal Integration: High-speed peripherals, including a 14-bit Dual ADC (LTC2145CUP-14) and DAC (AD9767), were integrated to handle analog and digital signals up to 125 MSPS.
Custom Modules: Three main modules were customized and embedded:
- Synchronized Acquisition and Processing (SAP).
- Multiplex Signal Generator (MSG).
- High-Speed Communication (HSC) via gigabit ethernet (UDP protocol).
Data Synchronization: Analog data from Photodetectors (PD) and digital photon counts from Avalanche Photo Diodes (APD) were synchronously sampled, processed, and encoded into 128-bit packets.
Signal Generation: The MSG module generated sine-type RF signals (0 to 62.5 MHz) and PWM-based digital pulses with 8 ns time resolution, used for coarse synchronization and frequency modulation (FM) of the microwave (MW) signals.
Calibration and Stability: Analog channels underwent amplitude and bias noise calibration, including temperature-dependent correction, to maintain accuracy across environmental variations (30 °C to 60 °C).
Quantum Application: The system was validated by performing complex quantum experiments, including Rabi oscillation and Lock-in detection, demonstrating its utility for high-sensitivity quantum metrology.

6CCVD Solutions & Capabilities

The successful replication and advancement of this high-performance ODMR system critically depends on the quality and customization of the diamond substrate, a core expertise of 6CCVD.

Requirement from Paper	6CCVD Solution & Capability	Technical Advantage
High-Quality NV Centers	Optical Grade Single Crystal Diamond (SCD)	Our SCD is grown via MPCVD with ultra-low strain and controlled nitrogen incorporation, maximizing NV center coherence time (T₂) and spin stability required for high-sensitivity quantum metrology and Lock-in detection.
Custom Antenna Integration	Custom Dimensions & Laser Cutting	The experiment uses an Ω-type slotline antenna mounted on the diamond. 6CCVD provides custom laser cutting and shaping services for SCD and PCD plates up to 125mm, ensuring precise fit for microwave circuitry.
Microwave Contact Pads	In-House Metalization Services	Antenna integration requires robust, low-resistance contacts. We offer custom metal stacks (e.g., Ti/Pt/Au, Ti/W/Cu) deposited directly onto the diamond surface, optimized for high-frequency MW signal delivery.
High-NA Optical Access	Ultra-Low Roughness Polishing	The single NV experiment uses a 100× objective (NA 1.35). 6CCVD guarantees surface roughness Ra < 1nm for SCD, minimizing scattering losses and maximizing fluorescence collection efficiency.
Ensemble Sensing	Polycrystalline Diamond (PCD) Substrates	For high-volume ensemble sensing applications, 6CCVD offers large-area PCD wafers (up to 125mm) with controlled NV density, providing a cost-effective alternative to SCD for large-scale sensor arrays.
Boron Doping (Future Extension)	Boron-Doped Diamond (BDD)	For electrochemical sensing or advanced quantum applications requiring conductive diamond, 6CCVD supplies BDD films (SCD or PCD) with tunable doping levels.

Engineering Support

6CCVD’s in-house PhD team specializes in optimizing MPCVD growth parameters to meet the stringent requirements of quantum applications. We offer consultation on material selection, nitrogen concentration control, and post-processing techniques (e.g., annealing for NV creation) to ensure the diamond substrate maximizes the performance of similar ODMR and Quantum Metrology projects.

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

View Original Abstract

We report a mixed-signal data acquisition (DAQ) system for optically detected magnetic resonance (ODMR) of solid-state spins. This system is designed and implemented based on a field-programmable-gate-array chip assisted with high-speed peripherals. The ODMR experiments often require high-speed mixed-signal data acquisition and processing for general and specific tasks. To this end, we realized a mixed-signal DAQ system that can acquire both analog and digital signals with precise hardware synchronization. The system consisting of four analog channels (two inputs and two outputs) and 16 optional digital channels works at up to 125 MHz clock rate. With this system, we performed general-purpose ODMR and advanced lock-in detection experiments of nitrogen-vacancy (NV) centers, and the reported DAQ system shows excellent performance in both single and ensemble spin cases. This work provides a uniform DAQ solution for the NV center quantum control system and could be easily extended to other spin-based systems.

Tech Support

Original Source

DOI: https://doi.org/10.1063/5.0070135

References

2020 - Efficient implementation of a quantum algorithm in a single nitrogen-vacancy center of diamond [Crossref]
2008 - Multipartite entanglement among single spins in diamond [Crossref]
2016 - Direct measurement of topological numbers with spins in diamond [Crossref]
2008 - Towards fault-tolerant quantum computing with trapped ions [Crossref]
2005 - Creation of a six-atom ‘Schrödinger cat’ state [Crossref]
2019 - Observation of parity-time symmetry breaking in a single-spin system [Crossref]
2008 - Simulating a quantum magnet with trapped ions [Crossref]
2015 - Quantum simulation of helium hydride cation in a solid-state spin register [Crossref]
2018 - Towards quantum simulation with circular Rydberg atoms [Crossref]
2020 - Detecting the out-of-time-order correlations of dynamical quantum phase transitions in a solid-state quantum simulator [Crossref]