Miniaturized quantum magnetometer offers new measurement possibilities for a wide range of applications

Fraunhofer IAF is presenting the latest version of its compact integrated quantum magnetometer at World of Quantum in Munich, June 24–27. The diamond-based system is characterized by its robustness, high integration density, and state-of-the-art measurement sensitivity. Thanks to its easy calibration, high sensitivity of a few picotesla, and high dynamic range, it offers new measurement possibilities for a wide range of applications in biomedicine, materials testing, navigation, and geology.

The highly integrated vector magnetometer developed by the Fraunhofer Institute for Applied Solid State Physics IAF is based on nitrogen vacancies (NV) in diamond and provides access to the smallest magnetic fields with a previously unattainable degree of flexibility and precision. The miniaturized measuring system offers completely new possibilities in applications that require precise measurement with minimal interference, such as in biochemical measurements of nerve pathways or in microelectronics.

“What makes the diamond-based NV vector magnetometer so special is its native and intuitive functionality, which enables it to precisely measure the vector components of Earth’s magnetic field under most operating conditions. This makes the sensor not only a technical innovation, but also a significant advance in sensor technology,” explains Dr. Michael Stoebe, Business Unit Manager for Quantum Devices at Fraunhofer IAF.

The unique properties of the NV center in the diamond lattice, which is arranged along the four crystal axes, enable all vector components of the magnetic field to be detected with a single sensor chip using diamond. This reduces the calibration effort and opens up new possibilities for applications that were previously limited by the restrictions of conventional magnetometers. This sensor is revolutionizing research in numerous fields and represents a significant step toward more precise and efficient measurement techniques.

Increased integration density and sensitivity

Researchers at Fraunhofer IAF have succeeded in reducing the size of their integrated quantum magnetometer by a factor of 30 in just one year. The sensor head now has a compact size comparable to conventional and industrially used optically pumped gas cell magnetometers (OPMs) with high sensitivity in the picotesla range. The diamond-based system stands out from competing technologies thanks to its high robustness and wide measuring range, which allows it to be used flexibly in a wide variety of measurement scenarios with extremely low calibration requirements.

“We are striving for even greater integration density, while increasing sensitivity. Our goal for the coming year is to reduce the size of the sensor by a factor of 5 again, while further increasing sensitivity to enable measurements in the sub-picotesla range,” emphasizes Dr. Stoebe.

The special feature of the integrated quantum magnetometers developed by Fraunhofer IAF is their optional water cooling, which ensures robust and reliable measurement of magnetic fields even under difficult operating conditions. This flexibility in design and integration is what sets the latest sensor prototypes from the Freiburg-based institute apart.

“We take an application-oriented approach to the continuous development of our sensor systems and respond to the individual requirements placed on our systems,” says Dr. Michael Kunzer, project manager at Fraunhofer IAF.

In addition to further developing the system, the core element of the sensor—its nitrogen-vacancy (NV)-doped diamond sensor head—is also being improved at Fraunhofer IAF. The synthetic diamond is grown at the institute in special reactors and further processed into quantum devices through the controlled exchange of carbon atoms with nitrogen atoms. The wafer sizes of the ultra-pure diamond are to be further developed next year from the current two inches to industrially scalable four-inch wafers.

GNSS—Safe navigation without GPS

Despite their high precision and coverage, today’s navigation systems are often prone to interference and are not available everywhere. Alternative navigation methods that function independently of global navigation satellite systems (GNSS) are therefore gaining in importance. Earth’s magnetic field is a promising basis for this, as it exhibits regional differences that can be used as an invisible map for autonomous navigation, especially in areas where GPS signals are disrupted or difficult to receive.

The quantum sensor developed at Fraunhofer IAF makes it possible to create comprehensive magnetic field maps and provide reliable navigation based on them. The vector magnetometer offers an autonomous, interference-free method for global positioning and navigation. It complements satellite-based navigation and also works without satellite signals, for example underwater, in canyons, underground, in buildings, or in tunnels.

Geological measurements quickly and contact-free

The quantum magnetometer developed by Fraunhofer IAF enables precise, contact-free localization of underground mineral deposits, thereby providing access to valuable resources. It can also detect unexploded ordnance over large areas, significantly reducing the risk to people in affected areas. Using the same principle as in navigation, the composition of Earth’s crust and its magnetic field can be used to draw conclusions about geological formations. Magnetic anomalies such as ore deposits or metallic objects such as unexploded ordnance can thus be detected.

The collected data can be converted into magnetic maps that show the locations of suspicious objects and provide information about their depth, shape, and size. This method enables comprehensive and non-invasive exploration of affected areas and the location of even deep-lying objects.