the enormous potential of quantum sensors to measure it

Among the quantum technologies with a bright future, quantum sensors are today the most advanced technology in this field. Quantum sensors are starting to come out of laboratories and even be commercialized. To understand the interest of these sensors, you must know, as their name indicates, that quantum sensors use the properties of quantum physics, which makes them extremely sensitive to the slightest disturbance in the environment and therefore to tiny signals of different natures.

Their use has a bright future with unprecedented performance gains and measurements with unrivaled precision. They will be used for numerous activities and applications such as earthquake prediction, underground probing, telecommunications, monitoring the electrical activity of neurons, one by one or even ultra-sensitive measurements of electric and magnetic fields. .

Among the most promising quantum sensors, we highlight in this article the diamond quantum magnetometers from the Quebec company SBQuantum. It is the first company to develop this type of sensor capable of providing measurements of the amplitude and orientation of the Earth’s magnetic field with unprecedented precision.

Proof of its technological advancement, SBQuantum was chosen, with its partner Spire Global, among three companies in the world to test its diamond-based sensor in space as part of the MagQuest challenge. This challenge, initiated by the National Geospatial-Intelligence Agency (NGA, an intelligence agency of the United States Department of Defense), is a multimillion-dollar competition to find more accurate and efficient ways to map the Earth’s electromagnetic field, also known as the Model global magnetic field (MMM).

To understand the whole point of measuring and mapping this electromagnetic field with a quantum sensor, we interviewed David Roy-Guay, CEO and co-founder of SBQuantum.

Futura: Can you explain what a diamond quantum magnetometer is?

David Roy-Guay : The diamond-based quantum magnetometer of SBQuantum exploits nitrogen-vacancy atomic impurities to achieve a very precise measurement of the vector magnetic field. To achieve this, we use the electronic spin of the impurity to produce the optically detected spin resonance. Following laser excitation in the green and microwave excitation near the WiFi frequency, the red light emitted by the diamond is modulated by the magnetic field. Thus, optically, we can detect the vector (orientation) of the magnetic field in a very small volume. What is exceptional about this impurity is that the quantum properties of spin are preserved even at room temperature.

Futura: Why choose quantum sensors to measure the magnetic field rather than other types of sensors?

David Roy-Guay : As their operation is based on quantum, quantum sensors are easily calibrated since we can always return to the fundamental description of the system to correct drifts in temperature and measured field. Based on atomic impurities, they are very compact and energy efficient, ideal for compact deployment platforms such as drones and nanosatellites.

Futura: Can we quantify, in terms of precision, the contribution of your sensors to the mapping of the global magnetic model?

David Roy-Guay : Global Magnetic Model (GMM) mapping is a very complex process, from collecting data from satellites to selecting good quality data to produce the model. Typically, only 1% of the data is retained to produce the map. Our sensor solution, combined with ML-based compensation algorithms, enables the deployment of nanosatellites the size of a liter of milk versus those the size of a bus. Ultimately, they will also increase the accuracy of measurements by a factor of 10 over one year, reducing calibration errors.

David Roy-Guay : The MMM was generated every 10 years and integrated into all navigation systems to indicate where magnetic north is located. It is now every 5 years since the magnetic north moves 50 kilometers per year. This can affect drone navigation, navigation accuracy of ships and aircraft in the Arctic. GPS provides location, not the direction you are pointing. In fact, we use the MMM every day since it’s behind the blue arrow on your cellular navigation app, to tell you to go left or right when you exit the subway. Near the poles, map updates are very important in guiding airplane pilots for whom magnetic compasses become decalibrated. Indeed, in Alaska, the name of an airstrip even had to be renamed following the update of the magnetic map!

Futura: Can we qualify this demonstration as a technological breakthrough?

David Roy-Guay : Absolutely. The increased stability of the reading of the magnetic field vector makes it possible to increase the reliability of compensation and interpretation algorithms, to facilitate deployment by drone and the use of magnetometry technology by non-initiates. Until now reserved for experts, magnetic fields will make it possible to navigate effectively without GPS underwater, underground and to detect metallic objects even out of line of sight, under snow, dust, smoke. Compactness and energy efficiency also make it possible to incorporate the technology into very small platforms.

Futura: A particular hard point?

David Roy-Guay : Although we have made a lot of progress, the technology is in its early years of development and new parameters related to quantum physics must be taken into account as performance is improved. In particular, the effect of different impurities in diamond, decoherence and optimal quantum control of impurities are very intensive R&D challenges to solve to achieve the ultimate sensitivity and precision of the system. Magnetism has been very well understood for centuries – however, surprisingly, the magnetization and demagnetization of the measurement platform (in this case the satellite) remains a very difficult phenomenon to compensate for since it must take into account the history of exposure to an external field. We are adapting our AI-based algorithmic strategies to address this, but it remains the No. 1 challenge in the field.

Futura: Can your quantum sensors or magnetometers be used for other purposes, for other scientific or commercial applications?

David Roy-Guay : Absolutely. Magnetometers are a platform technology, used among other things for mining exploration or for anti-submarine detection. Once the magnetic map has been built, we explore the possibility of using our sensors and a magnet to carry out navigation based solely on magnetic fields (without GPS). Other companies are developing diamond-based sensors for early cancer detection, molecular-scale magnetic resonance imaging for drug development, and for human/machine interfacing through fields created by the brain.

Futura: What benefits and interests for the National Geospatial-Intelligence Agency?

David Roy-Guay : The MMM is currently generated using data from the ESA Swarm mission. As this mission is at the end of its life, the National Geospatial-Intelligence Agency is exploring agile, low-cost ways to generate high-precision magnetic data for production of future editions of the MMM. This is truly a critical capability for vehicle and aircraft navigation for the entire planet and will also provide essential data to deepen our understanding of phenomena in the Earth’s core, the lithosphere and could even refine our theories on how animals are oriented in their migrations!