Towards ubiquitous radio access using nanodiamond based quantum receivers
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2025-03-31 |
| Journal | Communications Engineering |
| Authors | Qunsong Zeng, Jiahua Zhang, Madhav Gupta, Zhiqin Chu, Kaibin Huang |
| Institutions | University of Hong Kong |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThis research validates a novel quantum receiver architecture utilizing Nitrogen-Vacancy (NV) centers in Fluorescent Nanodiamonds (FNDs) to address critical challenges in 6G wireless communication, focusing on miniaturization and multi-user access.
- Ubiquitous 6G Access: The proposed system uses FNDs as compact, robust nano-antennas, enabling simultaneous multiple access for several users, overcoming limitations associated with large traditional base stations.
- Quantum Demodulation: Multi-user signals are demodulated by exploiting the unique Optically Detected Magnetic Resonance (ODMR) response of individual FNDs, which generates distinguishable patterns of fluorescence intensity based on incident microwave power and frequency.
- High Fidelity Transmission: Experimental results demonstrated exceptional performance, achieving a Bit Error Ratio (BER) of 0% for Amplitude Modulation (AM) and a low BER of 0.146% for Frequency Modulation (FM) in two-user digital image transmission.
- Tunable Multi-Band Capability: The receiver supports communication across different frequency bands (e.g., 2700 MHz to 3020 MHz) by applying external static magnetic fields to detune the NV center spin resonance frequencies.
- Reference-Free Design: An orthogonal multiple access scheme was demonstrated that decouples signals without requiring the transmission of reference bits, significantly reducing communication overhead (achieving a BER of 0.0657%).
- Practical Implementation: A miniaturized FND-receiver prototype was successfully constructed (300 mm x 300 mm x 200 mm, 8 kg), validating the immediate potential for practical deployment.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Receiver Prototype Dimensions | 300 x 300 x 200 | mm | Size of the compact device implementation. |
| Receiver Prototype Weight | ~8 | kg | Total weight (6 kg optical breadboards, <2 kg electronics). |
| Total Power Consumption | 1.87 | W | Sum of camera (1.17 W) and laser (0.7 W) power. |
| FND Diameter | 100 | nm | Size of Fluorescent Nanodiamonds used. |
| ODMR Sensitivity | 0.735 | ”T · Hz-1/2 | Sensitivity for detecting the magnetic component of the incident field. |
| Zero-Field Splitting (ZFS) | ~2.87 | GHz | Ground state energy gap of the NV center. |
| Tunable Frequency Range (Low Band) | 2700 to 2776 | MHz | Demonstrated multi-band operation (0) â (-1) transition. |
| Tunable Frequency Range (High Band) | 2963 to 3020 | MHz | Demonstrated multi-band operation (0) â (+1) transition. |
| Bit Error Ratio (AM) | 0 | % | Two-user digital transmission using amplitude modulation. |
| Bit Error Ratio (FM) | 0.146 | % | Two-user digital transmission using frequency modulation (handwritten digits). |
| Bit Error Ratio (Reference-Free) | 0.0657 | % | Orthogonal multiple access demonstration. |
| Magnetic Field Gradient | ~0.023 | G/”m | Gradient required for reference-free signal decoupling across FNDs. |
| Estimated Utilization Ratio | 11.1% (5 out of 45) | % | Estimated capacity within a 75 ”m x 75 ”m field of view. |
| Estimated Symbol Rate | 1 | Mega-symbols/second | Constrained by the NV center transition rate (0.98 ± 0.31 MHz). |
Key Methodologies
Section titled âKey MethodologiesâThe FND-receiver relies on Optically Detected Magnetic Resonance (ODMR) to convert microwave signals into detectable fluorescence intensity changes, enabling multi-user demodulation.
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Sample Preparation:
- Coverslip substrate was treated for 10 minutes using a UV-Ozone Cleaner (1.3 W) to enhance hydrophilicity.
- Commercial 100 nm FNDs (0.05 mg/ml concentration) were sonicated for 5 minutes.
- The solution was spin-coated onto the substrate (1500 r/min for 20s, followed by 3000 r/min for 50s, repeated 10 times) to ensure complete FND coverage.
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ODMR Experimental Setup:
- A home-built upright widefield microscope was used for NV photoluminescence imaging.
- FND excitation was achieved using a 532 nm green laser.
- Emitted fluorescence was collected by an Electron-Multiplying CCD (EMCCD) camera (Evolve 512 Delta) equipped with a 650 nm long-pass filter.
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Microwave Transmission and Synchronization:
- The FND substrate was mounted on a self-designed PCB with a microwave antenna.
- Two independent microwave signals were generated (SynthHD source) and amplified (Mini-Circuits amplifier).
- Continuous Wave ODMR (CWODMR) technique was used for measurement. The microwave was applied for 30 ms during the 40 ms image acquisition time, with 10 ms allocated for temperature balancing.
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Compact Device Fabrication:
- The prototype replaced bulky components with miniaturized alternatives: a Pigtailed Laser Diode (LP520-SF15A) for excitation and a CMOS camera (Basler CM254) for detection.
- A concave mirror (CM254-100-E02) was used in place of a convex lens to reduce the overall optical path length and space requirements.
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Signal Demultiplexing:
- Users transmit reference bits first, creating a set of reference fluorescence images (intensity matrices) corresponding to all possible bit-pair combinations.
- During data transmission, the received fluorescence image at each sampling point is compared to the reference images.
- The bit-pair corresponding to the reference image with the minimum Mean Squared Error (MSE) is selected as the detected signal.
Commercial Applications
Section titled âCommercial ApplicationsâThe integration of quantum sensing technology (NV centers) into communication receivers offers significant advantages for next-generation wireless systems and specialized sensing markets.
- 6G Ubiquitous Radio Access: Provides a solution for the massive deployment of compact, low-power base stations and access points required for seamless connectivity in 6G networks.
- Millimeter-Wave and Terahertz Communication: The ability to tune the operating frequency using external magnetic fields allows the receiver to adapt to high-frequency bands (30-300 GHz) envisioned for 6G, potentially extending to Terahertz bands using frequency mixers.
- High-Density Multi-User Systems: The multiple access scheme, particularly the reference-free orthogonal design, is ideal for dense urban environments or large-scale IoT networks where high user capacity and low communication overhead are critical.
- Quantum-Enhanced RF Spectrum Analysis: The high sensitivity of the NV centers to microwave fields makes the technology suitable for high-resolution, wide-bandwidth instantaneous radio frequency spectrum analysis and magnetometry.
- Noise-Resistant Receivers: Due to the optical nature of the detection and down-conversion process, these receivers are inherently resistant to electrical interference, making them valuable for deployment in electrically noisy industrial or medical environments.
- Miniaturized IoT and Mobile Devices: The compact, low-power (1.87 W) design enables the integration of advanced quantum sensing capabilities into small, energy-efficient mobile or Internet of Things (IoT) devices.