Momentum is rising quickly: the United Nations General Assembly declared 2025 the International Year of Quantum Science and Technology (IYQ) (proclaimed 7 June 2024), spotlighting quantum science’s impact on technology, industry, and society.
Why Synthetic Diamond Matters
Natural diamonds are scarce and highly variable in purity and crystal defects, which limits their suitability for engineered quantum devices. Modern applications increasingly rely on synthetic diamond with controlled crystal quality and defect chemistry—especially for producing reproducible NV-center diamond sensors.
Two widely used synthetic routes are:
Chemical Vapour Deposition (CVD)
Chemical vapour deposition (CVD) is often the preferred approach for fabricating high-quality single-crystal diamond films used in quantum sensing.
CVD diamond growth leverages the small stability difference between carbon allotropes (sp² and sp³). Under suitable conditions—typically with surface temperatures above ~600°C and abundant atomic hydrogen—diamond growth is promoted while unwanted graphitic carbon is suppressed. Growth conditions are created using a hot gas/plasma environment (often >2000°C gas temperature), a carbon source (e.g., methane), and hydrogen to guide surface chemistry and crystal formation.
High Pressure, High Temperature (HPHT)
Most synthetic diamond by volume is produced via HPHT (high pressure, high temperature) methods, which mimic the thermodynamic conditions of natural diamond formation and often use a metal catalyst as a transport medium for dissolved carbon.
HPHT diamonds typically grow as cuboctahedra (multiple growth directions). They can exhibit a yellow tint due to nitrogen incorporation during growth—an “impurity” that becomes extremely valuable for quantum applications because it enables formation of nitrogen-vacancy (NV) centers.
Nitrogen-Vacancy (NV) Quantum Diamonds
NV centers are crystal defects in diamond where a nitrogen atom sits adjacent to a missing carbon atom (a vacancy). These defects behave like controllable, light-addressable quantum systems—often described as “artificial atoms”—with quantum properties such as spin that are highly sensitive to their environment.
A common pathway to NV-center diamond includes:
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Growing diamond (often via CVD for single-crystal films) with carefully controlled nitrogen levels.
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Creating vacancies (e.g., via electron irradiation) by displacing carbon atoms from the lattice.
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Annealing the diamond (commonly above ~700°C) so vacancies become mobile and can pair with nitrogen atoms to form NV centers.
NV centers have spin states that can be manipulated with microwaves and read out optically, enabling optically detected magnetic resonance (ODMR)—the core measurement technique behind many diamond quantum sensors.
Uses of Quantum Diamonds
Quantum sensing with ODMR
NV centers can fluoresce (emit light) when optically excited. By monitoring changes in fluorescence while applying microwaves and magnetic fields, ODMR can be used to detect extremely small variations in:
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Magnetic fields (magnetometry)
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Electric fields and strain
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Temperature (in some configurations)
This sensitivity is why NV-diamond platforms are widely explored for next-generation sensing in biology, materials science, and quantum engineering.
Ultra-sensitive diagnostics and biosensing
A promising direction is nanodiamond-based diagnostics, where NV-containing nanodiamonds are functionalised (e.g., with antibodies) to capture biological targets. Because NV fluorescence is measurable and can be enhanced/controlled via ODMR, this approach can enable very high sensitivity in assay-style detection—useful for early-stage biomarkers and infectious disease screening concepts.
Brain and cardiac magnetic field detection
Neural activity generates magnetic fields that pass through the skull. Detecting these magnetic fields directly can complement electrical measurements. NV-diamond sensors have a practical advantage over some superconducting sensor approaches because diamond devices can operate without cryogenic cooling, supporting more compact and scalable sensing hardware.
Navigation resilient to jamming
GPS is vulnerable to interference and signal loss. Because Earth’s magnetic field varies by location, NV-diamond magnetometers could support positioning methods that supplement or back up satellite navigation, especially where GPS is degraded.
Quantum computing potential
Some qubit platforms require deep cryogenic cooling, complicating scale-up. NV centers are notable because their spin properties can be maintained and read out using light at or near room temperature, making them an interesting candidate for certain quantum computing architectures and hybrid quantum devices.
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Images courtesy of Nature
