The Fundamentals of Quantum Sensing and Metrology

By Ankit SinghReviewed by Susha Cheriyedath, M.Sc.Sep 18 2024

Quantum sensing and metrology leverage the unique principles of quantum mechanics to measure physical quantities with unprecedented accuracy. These advanced technologies are rapidly gaining attention across industries like healthcare, defense, and navigation, where precise measurements and sensitive detection are critical for innovation.

Image Credit: ILIA NEZNAEV/Shutterstock.com

Unlike classical sensors, which rely on distinct states (e.g., a thermometer reading a specific temperature), quantum sensors exploit phenomena like superposition and entanglement, enabling capabilities that go beyond the limits of classical systems. From detecting minute magnetic fields to measuring time with extreme precision, quantum technologies are pushing the boundaries of what is possible in measurement science.

The Evolution of Quantum Sensing and Metrology

The development of quantum sensing and metrology began in the early 20^th century with the rise of quantum mechanics, a revolutionary field that transformed our understanding of reality. Early pioneers like Albert Einstein and Erwin Schrödinger introduced fundamental concepts, including quantum entanglement—a phenomenon where particles become intertwined, influencing each other regardless of distance.

Practical applications of these theories emerged by the mid-20^th century. A notable breakthrough was the invention of the atomic clock in the 1950s, which dramatically improved timekeeping precision. Atomic clocks, which measure time-based on the oscillations of atoms like Cesium or Rubidium, revolutionized global positioning systems (GPS), telecommunications, and fundamental scientific research. This technology remains a cornerstone of modern quantum sensing.

The 1990s witnessed the rise of quantum magnetometry, a technology that enabled the detection of extremely weak magnetic fields. Applications of quantum magnetometry range from archaeological exploration to advanced medical diagnostics, such as brain imaging through magnetoencephalography (MEG).

In the 21^st century, the convergence of quantum information science and sensing technologies expanded the reach of quantum metrology. From quantum-enhanced MRI machines in healthcare to quantum radar in defense, quantum sensors are reshaping industries with capabilities previously unimaginable. The future of these technologies promises even greater innovations fueled by advancements in quantum computing and artificial intelligence.

The Impact of Quantum Technology on Data Security

Decoding Quantum Sensing: Superposition and Entanglement

At the heart of quantum sensing are three core principles: superposition, entanglement, and quantum coherence. These phenomena distinguish quantum sensors from classical sensors and allow for highly sensitive measurements.¹

• Quantum superposition allows particles like atoms or photons to exist in multiple states simultaneously. For instance, in an atomic interferometer, atoms can be placed in two states—one influenced by an external force and one unaffected. The interference between these states enables extremely precise measurements of the external force, such as gravity.^1,2

• Quantum entanglement refers to the correlation between particles, where the state of one particle instantaneously affects the state of another, regardless of distance. This property enhances the sensitivity of quantum measurements. For example, quantum magnetometers use entangled particles to detect minute magnetic field changes, offering advantages in fields like brain imaging and materials research.^1,2

• Quantum coherence is the ability of a quantum system to maintain a stable superposition over time. The longer coherence is preserved, the more precise the measurement. Atomic clocks rely on maintaining coherence between quantum states of atoms to measure time with extreme accuracy, a capability crucial for timekeeping and GPS systems.^1,2

Advances in Quantum Metrology

Quantum metrology is the science of using quantum mechanical phenomena to make high-precision measurements. It is central to fields like timekeeping, navigation, and fundamental physics, where accuracy is essential. One of the key objectives in quantum metrology is to exceed the Standard Quantum Limit (SQL), a precision barrier imposed by classical physics. Techniques such as quantum squeezing, which reduces uncertainty in one property while increasing it in another, allow for measurements that surpass this limit.^2,3,4

Quantum interferometry is another essential technique in metrology. By splitting a quantum state into two distinct paths and recombining them after one path is exposed to the measured quantity, interferometers provide detailed information about external forces. This approach is critical in applications like gravitational wave detection and advanced atomic clocks, where extraordinary precision is required.^2,3

A significant challenge in quantum metrology is managing noise and decoherence, which can degrade the precision of quantum measurements. To address this, researchers are developing quantum error correction techniques, which protect quantum systems from environmental disturbances, ensuring that quantum metrological systems can operate reliably over extended periods.^2,3

Breakthroughs in Quantum Sensing and Metrology

Recent research has pushed the boundaries of quantum sensing and metrology, leading to groundbreaking advances in both theory and application. A recent study published in Frontiers in Physics introduced a weak force sensor using a coherent quantum noise cancellation (CQNC) scheme in a hybrid cavity optomechanical system with ultracold atoms and an optical parametric amplifier (OPA). This innovation, based on a hybrid cavity optomechanical system with ultracold atoms, surpasses the Standard Quantum Limit (SQL) and improves force-sensing accuracy, even at low input power levels.⁵

Another breakthrough study published in Geophysical Research Letters demonstrated the first use of an absolute atom interferometry gravimeter to monitor an active volcano. Installed near Mt. Etna, the quantum device continuously measured gravity changes despite challenging environmental conditions and volcanic tremors. Despite challenging conditions, this quantum device continuously measured gravity changes associated with magma dynamics, providing new insights into volcanic processes. Such developments highlight the potential of quantum sensors in geophysical monitoring and beyond.⁶

Industry Leaders in Quantum Sensing and Metrology

The rapid advancements in quantum sensing and metrology are being driven not just by academic research but by significant efforts from industry leaders. Companies across various sectors are recognizing the potential of quantum technologies, and many are at the forefront of integrating these capabilities into their platforms, products, and solutions.

IBM, Honeywell, and Google are pioneers in the field of quantum computing, but they are also investing heavily in quantum sensing and metrology. IBM’s research in quantum systems extends into sensing, where it is developing quantum-enhanced devices that promise to deliver ultra-precise measurements in fields ranging from healthcare to environmental monitoring. Honeywell, a leader in both quantum computing and industrial automation, is leveraging quantum principles to develop sophisticated navigation systems and other sensing technologies. Google, through its Quantum AI lab, is exploring how quantum sensing can enhance everything from materials science to data security.

Startups are also playing a crucial role in the development of quantum sensing technologies. Q-CTRL, an Australian-based company, has become a major player by focusing on quantum error correction for sensing applications. Quantum systems are notoriously sensitive to environmental noise, which can degrade their accuracy. Q-CTRL’s software tools help stabilize these systems, ensuring that quantum sensors can function in real-world conditions without being compromised by noise or other forms of interference. Their solutions are particularly relevant in defense, where reliable, noise-resistant quantum sensors could be used in navigation, communication, and intelligence gathering.

AOSense, another leader in the quantum space, specializes in quantum-based inertial sensors and atomic clocks. These technologies are crucial for applications like navigation systems, particularly in environments where GPS is unreliable or unavailable, such as underwater or in deep space. AOSense’s sensors are already being deployed in aerospace, where precision is key for long-term missions. Their atomic clocks are also used in advanced telecommunications and scientific research, where precise timekeeping is essential for synchronizing systems or conducting highly accurate experiments.

The Future Impact of Quantum Sensing and Metrology

The future of quantum sensing holds enormous potential, and it is likely to revolutionize numerous industries in the coming years.

• Healthcare: In the medical field, quantum-enhanced sensors could enable diagnostic tools that provide unprecedented detail at the molecular level. For example, quantum-enhanced MRI machines could produce images with far greater resolution than traditional MRI, allowing doctors to detect diseases like cancer at much earlier stages. Similarly, quantum sensors that measure minute changes in electromagnetic fields could lead to breakthroughs in brain-computer interfaces, enabling more accurate monitoring of neural activity, which is critical for understanding neurological disorders.

• Defense and Navigation: In defense, quantum gyroscopes and accelerometers offer unparalleled accuracy for navigation systems. These technologies, which rely on quantum superposition and coherence to detect the tiniest changes in movement or orientation, could be vital for submarines, aircraft, and other military vehicles that require highly precise navigation in GPS-denied environments. Quantum sensors also promise to enhance quantum radar, which can detect stealth aircraft or other objects that traditional radar systems might miss. These advancements could significantly alter the landscape of modern defense, making detection systems far more reliable and sensitive to threats.

• Telecommunications and Timing: Quantum-enhanced atomic clocks could improve the synchronization of global communication networks and power more accurate GPS systems. Telecommunications, which relies on precise timing for data transfer and synchronization, could benefit from quantum metrology by reducing latency and increasing network reliability. This would have significant implications for industries like financial services, where milliseconds can make a difference in high-frequency trading, as well as for emerging technologies like 5G and Internet of Things (IoT) systems.

  Quantum Computing and the IoT

   

• Environmental Monitoring: Quantum sensors are also set to impact environmental monitoring. With the ability to detect incredibly subtle changes in gravitational fields or atmospheric conditions, these sensors could be used to monitor volcanic activity, seismic movements, or even climate changes with a level of accuracy that traditional sensors cannot match. For example, quantum gravimeters have already been used to detect mass variations inside volcanoes, offering early warning signs of eruptions. In climate science, quantum sensors could provide more precise measurements of greenhouse gas emissions, helping scientists to better understand and mitigate climate change.

  Real-Time Environmental Monitoring With Quantum Sensors

   

• Fundamental Research and Space Exploration: Quantum sensing is not only practical but also fundamental for advancing research in physics and astronomy. In space exploration, where precision in measurement is critical, quantum sensors could enable new discoveries by detecting gravitational waves or mapping distant planetary surfaces with high resolution. Quantum metrology could also play a role in testing fundamental physical laws, such as Einstein’s theory of general relativity, under extreme conditions, potentially leading to new breakthroughs in our understanding of the universe.

Quantum Sensing in Space Exploration: Technologies and Applications

Expanding Commercialization and Industry Applications

As quantum sensing technologies mature, the commercialization of these innovations is accelerating. In addition to established tech giants and startups, industries such as aerospace, automotive, and manufacturing are exploring how quantum metrology can improve product design, production accuracy, and operational efficiency. For instance, automakers are investigating how quantum sensors could improve the safety and precision of autonomous vehicles, allowing for better navigation and obstacle detection in complex environments.

Meanwhile, pharmaceutical companies are looking into quantum sensors for drug discovery, where detecting interactions at the molecular level could streamline the development of new treatments. Similarly, chemical industries could use quantum sensing to monitor reactions in real-time with unprecedented precision, leading to safer and more efficient manufacturing processes.

Conclusions

Quantum sensing and metrology have the potential to transform industries globally, providing unparalleled precision and sensitivity. While challenges remain, continued research and technological progress will likely enable these technologies to become widely adopted in the coming decades, revolutionizing the measurement of human-physical world interactions.

Quantum Machine Learning: The Future of AI

References and Further Reading

1. Kantsepolsky, B. et al. (2023). Exploring Quantum Sensing Potential for Systems Applications. IEEE Access. DOI:10.1109/access.2023.3262506. https://ieeexplore.ieee.org/abstract/document/10083135
2. DeMille, D. et al. (2024). Quantum sensing and metrology for fundamental physics with molecules. Nature Physics, 20(5), 741-749. DOI:10.1038/s41567-024-02499-9. https://www.nature.com/articles/s41567-024-02499-9
3. Liu, Q. et al. (2024). Fully-Optimized Quantum Metrology: Framework, Tools, and Applications. Advanced Quantum Technologies, 2400094. DOI:10.1002/qute.202400094. https://onlinelibrary.wiley.com/doi/full/10.1002/qute.202400094
4. Huang, J. et al.  (2024). Quantum Metrology Assisted by Machine Learning. Advanced Quantum Technologies, 2300329. DOI:10.1002/qute.202300329. https://onlinelibrary.wiley.com/doi/full/10.1002/qute.202300329
5. Singh, S. K. et al. (2023). Enhanced weak force sensing based on atom-based coherent quantum noise cancellation in a hybrid cavity optomechanical system. Frontiers in Physics, 11, 1142452. DOI:10.3389/fphy.2023.1142452. https://www.frontiersin.org/journals/physics/articles/10.3389/fphy.2023.1142452/full
6. Antoni-Micollier, L. et al. (2022). Detecting Volcano-Related Underground Mass Changes With a Quantum Gravimeter. Geophysical Research Letters, 49(13), e2022GL097814. DOI:10.1029/2022GL097814. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2022GL097814

Disclaimer: The views expressed here are those of the author expressed in their private capacity and do not necessarily represent the views of AZoM.com Limited T/A AZoNetwork the owner and operator of this website. This disclaimer forms part of the Terms and conditions of use of this website.