Diamond sensing and magnetic navigation

What an NV centre is

A nitrogen-vacancy (NV) centre is a point defect in the diamond lattice: a nitrogen atom sitting next to a missing carbon atom. The defect has electron spin states whose energies shift in a magnetic field. Shining green light on the diamond both prepares those spin states and reads them out through changes in red fluorescence, while a microwave field drives transitions between them — a technique called optically detected magnetic resonance (ODMR).¹

Because NV centres can sit along any of four crystal directions, an ensemble of them can measure the magnetic field as a vector, not just its magnitude.¹ For the physics and field results in more depth, see the technical primer on NV magnetometry for navigation.

Why it matters for navigation

Magnetic anomaly navigation estimates position by comparing measured magnetic field against anomaly maps (see the principle and its limits in the literature²). Its accuracy depends on how well the sensor measures small field variations while moving, in the presence of the vehicle's own field. Diamond sensors are interesting for that job because they are:

• Solid-state — no vapour cells or cryogenics in the sensing element.
• Room-temperature — the NV spin physics works at ambient temperature.⁵
• Vector-capable — field direction as well as magnitude, which can help separate platform effects from the external field.

What has been demonstrated

Laboratory ensemble magnetometers have reported sensitivities of around 50 pT/√Hz per Cartesian axis with a 12.5 kHz bandwidth,³ and around 0.9 pT/√Hz in the 10–1000 Hz band using flux concentrators, with about 200 mW of laser and 20 mW of microwave power.⁴ A 2020 review notes that present ensemble devices remain orders of magnitude from their theoretical limits — there is headroom, but also a gap between physics and product.⁵

Research groups are working on miniaturisation for navigation; Fraunhofer IAF, for example, reported shrinking an NV vector magnetometer by a factor of 30 within a year.⁶ In mineral exploration, a Canada–UK project has flown a diamond quantum magnetometer on a drone.⁷ These are research and company-reported results, not independent benchmarks.

Engineering trade-offs

• Optical and microwave power. The laser and microwave drive dominate the power budget; the best laboratory sensitivities use hundreds of milliwatts of optical power.⁴
• Temperature. The NV resonance shifts by roughly 74 kHz per kelvin, so thermal drift must be compensated, for example by measuring multiple resonances.⁸
• Size versus sensitivity. Sensitivity improves with the number of NV centres and collected light, which pushes against miniaturisation.
• Vector calibration. Using the four crystal axes for vector measurement requires careful calibration of their orientation and cross-coupling.¹
• The platform still matters. A better sensor does not remove the vehicle's magnetic interference; compensation and installation remain essential.²

Limitations

• Headline sensitivities are laboratory figures measured under specific conditions and bandwidths; they are not directly comparable with fielded systems.
• Navigation performance depends at least as much on anomaly-map quality, altitude and platform compensation as on sensor sensitivity.
• Diamond is one of several quantum magnetometer technologies; optically pumped magnetometers remain the workhorse of airborne magnetic surveys today.

About this resource

Orbital Quantum is a Canadian company developing True North Navigation™ quantum magnetometer modules for GPS-independent positioning, currently offered as Founder's Edition units for partner evaluation ahead of broader commercial release. See how True North Navigation works.

This site explains diamond quantum sensing in general. It does not describe the internal design of Orbital Quantum's modules.

Sources

1. Lönard et al. — Limits of absolute vector magnetometry with NV centers in diamond (2025) — arxiv.org
2. Gnadt et al. — Signal enhancement for magnetic navigation challenge problem (2020) — arxiv.org
3. Schloss et al. — Simultaneous broadband vector magnetometry using solid-state spins, Phys. Rev. Applied 10, 034044 (2018) — arxiv.org
4. arXiv:1911.05070 — diamond magnetometer with ferrite flux concentrators (2019) — arxiv.org
5. Barry et al. — Sensitivity optimization for NV-diamond magnetometry, Rev. Mod. Phys. 92, 015004 (2020) — arxiv.org
6. GPS World — Quantum magnetometer could solve GNSS-denied navigation problems (Jun 2025) — www.gpsworld.com
7. Newswire.ca — SBQuantum & Silicon Microgravity QUAMINEX announcement (Mar 2024) — www.newswire.ca
8. Acosta et al. — Temperature dependence of the NV magnetic resonance in diamond, PRL 104, 070801 (2010) — arxiv.org