Researchers at the Fraunhofer Institute for Applied Solid State Physics IAF have managed to harness the great potential of quantum sensor technology based on nitrogen-vacancy (NV) centers in a unique measurement setup. Their wide-field magnetometer enables the magnetic stray field of a sample to be measured rapidly over a large range. Its high measurement accuracy is characterized by a resolution down to the nanometer range and is absolutely quantifiable. This measurement method opens up new avenues in metrology and is suitable for various industries such as (nano-)electronics, material sciences or biomedicine due to its wide range of applications, from inorganic to organic samples.

The innovative measurement system was developed in the course of the Fraunhofer lead project QMag, which is funded in equal parts by the Fraunhofer-Gesellschaft and the Ministry of Economics, Labor and Tourism of Baden-Württemberg. In the course of the project, a concentrated magnetometry expertise and infrastructure has developed in Freiburg im Breisgau at the three institutes Fraunhofer IAF, IPM and IWM, which together form the Quantum Sensing Hub Freiburg.

The wide-field magnetometer will be presented at this year’s LASER World of QUANTUM in Munich from June 27 to 30. The measurement system is part of the Quantum Sensing Hub Freiburg, which is presenting itself at the joint booth of the Fraunhofer-Gesellschaft.

Magnetometry with diamond

Wide-field magnetometry is based on NV centers in thin diamond films and is a young approach in quantum sensing. The measurement setup developed at Fraunhofer IAF uses an arbitrary waveform generator (AWG), which generates microwave radiation and triggers a laser and the recording time window of a camera with nanosecond precision. By using different measurement protocols, this allows for high flexibility and precision of measurements.

“The wide-field magnetometer benefits not only from our improved setup, but also from the growth process developed at Fraunhofer IAF for diamond plates, which we use as sensors,” explains Dr. Jan Jeske, deputy business unit manager quantum devices at Fraunhofer IAF. The substrates grown at the institute are based on (100)-oriented, pure, undoped diamond of type 'IIa' with a thickness of 500 μm and an area of 4 x 4 mm. This substrate is overgrown with a thin layer in which the NV centers for the sensor application are generated close to the sample.

Measurement advantages of the wide-field magnetometer

In materials science, experimental methods are used to characterize polycrystalline materials in order to obtain a microscopic understanding of the macroscopic material behavior. This makes it possible to better understand materials and optimize their properties. However, current methods usually rely on long measurement times and large experimental facilities. Often, vacuum conditions or high-energy particles are also necessary, which can have a detrimental effect on the sample material.

Wide-field magnetometry based on NV centers is an alternative, non-invasive method that operates at room temperature. This opens up new possibilities for insights into the microscopic magnetic field distribution, which has great potential for material analyses. The system is not limited to inorganic material samples, but can also be applied to organic samples due to its comparatively low demands on the measurement environment. These measurement properties, coupled with the high measurement speed of the method developed at Fraunhofer IAF, allow even complex measurements such as fluctuations, alternating fields and alternating current (AC) measurements—paving the way for new material analysis methods.

Quantum Sensing Hub Freiburg

The Quantum Sensing Hub Freiburg concentrates the quantum sensing expertise and infrastructure of the three institutes Fraunhofer IAF, IPM and IWM. It offers new approaches, solutions and applications in the field of quantum sensor technology and sensor systems for customers and partners from industry and research. The focus is on two classes of quantum magnetometers with complementary properties: magnetometers based on NV centers in diamond and optically pumped magnetometers (OPMs) based on alkali atoms.

Quantum magnetometry at LASER World of QUANTUM 2023

At LASER World of QUANTUM, which will take place in Munich from June 27 to 30, 2023, parallel to LASER World of PHOTONICS, the institutes Fraunhofer IAF, IPM and IWM will present their consolidated expertise in the field of quantum magnetometry. Fraunhofer IAF will present its wide-field magnetometer to the interested public for the first time. The Quantum Sensing Hub Freiburg is part of the Fraunhofer joint booth 523 in hall A1.