NV Diamond Sensors Under Megabar Pressure: What the Anvil-Cell Experiments Show

Short answer: Researchers have published laboratory experiments that put nitrogen-vacancy (NV) centres inside diamond anvil cells and read out magnetic signals at very high pressure. A 2022 paper reports spin control up to 1.4 Mbar, a 2019 Science paper reports stress and magnetism imaging, and a 2024 paper reports imaging of a magnetic transition in magnetite. These are research results, not products.

Why put a quantum sensor in a pressure cell?

A diamond anvil cell squeezes a tiny sample between two diamond tips. It is a standard tool for studying how matter behaves under extreme pressure. The difficulty, as the 2022 paper in Chinese Physics Letters puts it, is that in situ magnetic sensing at ultrahigh pressure is still challenging. Many ordinary magnetometers cannot sit inside the cell.

The NV centre is a point defect in diamond whose electron spin can be read out with light and microwaves. Because the sensor is part of the diamond itself, it can sit right next to the sample. That is the basic appeal described across all three papers.

What does the 2022 paper report?

The Chinese Physics Letters paper, "Optically Detected Magnetic Resonance of Diamond Nitrogen-Vacancy Centers under Megabar Pressures", states that the authors demonstrated optically detected magnetic resonance and coherent quantum control of NV centres inside a diamond anvil cell up to 1.4 Mbar. They quantified how the optical and spin properties change with pressure. They also report tracking the evolution of an external magnetic field at about 80 GPa.

The abstract frames this as a step towards quantum sensing under extreme conditions. It does not claim a finished instrument.

What does the 2019 Science paper report?

The Science paper, "Imaging stress and magnetism at high pressures using a nanoscale quantum sensor", describes a platform that integrates NV centres directly into the culet of the diamond anvils. According to the abstract, the authors performed diffraction-limited imaging of stress fields and of magnetism as a function of pressure and temperature. They report quantifying all normal and shear stress components and demonstrating vector magnetic field imaging.

The abstract names two test cases. One is the pressure-driven phase transition in iron between its alpha and epsilon forms. The other is the pressure-temperature phase diagram of gadolinium. It also describes a second sensing mode based on noise spectroscopy, which the authors say can characterise phase transitions even when no static magnetic signature is present.

What does the 2024 paper report?

The Nature Communications paper, published 14 October 2024, is titled "Imaging magnetic transition of magnetite to megabar pressures using quantum sensors in diamond anvil cell". Its abstract says the authors modulated the uniaxial stress along the NV axis to get around pressure limits on the sensor. They report an in situ magnetic detection technique at megabar pressures with a sensitivity of about 1 microtesla per root hertz and sub-micron spatial resolution.

Using this, they report imaging magnetic domains in Fe3O4 and observing a change from ferrimagnetic to weak ferromagnetic and then paramagnetic as pressure rises. The authors say this contributes to understanding how magnetism evolves under complex factors such as spin crossover and structural phase transitions.

What do the three have in common?

All three papers are laboratory demonstrations on diamond samples and test materials. Each one pushes the usable pressure range or the imaging ability of NV sensors. The 2019 and 2024 papers move from single readings towards images. None of the abstracts we could read claims a commercial or deployed system, and this post does not either.

How to read this

The numbers above, including 1.4 Mbar, 80 GPa and 1 microtesla per root hertz, are the authors' own reported values from their abstracts. We did not reproduce or test them. Peer-reviewed venues are named for each paper, but peer review does not guarantee that other groups will get the same results.

FAQ

Why use NV centres instead of a conventional magnetometer?

The 2022 abstract says in situ magnetic sensing at ultrahigh pressure is still hard. The NV centre is built into the diamond, so it can sit next to the sample inside the cell, which is the idea behind all three papers.

What pressure did the experiments reach?

The 2022 paper reports spin control up to 1.4 Mbar. The 2024 paper describes sensing in the megabar range. These are the authors' reported figures.

What samples were measured?

The 2019 Science abstract names iron and gadolinium. The 2024 abstract names magnetite, Fe3O4.

Does this mean quantum sensors are in commercial use for materials research?

No. The abstracts describe laboratory experiments. They say nothing about commercial availability, and we make no such claim.

Are the results settled?

They are published, peer-reviewed results from individual groups. Independent replication would be the next test, and the abstracts do not describe it.