Advances in quantum sensing have revolutionized the way scientists measure previously unimaginable things such as vibrations of atoms, properties of individual photons, and fluctuations associated with gravitational waves. One promising quantum mechanical trick called “spin squeezing” has long been recognized for its potential to enhance the capabilities of quantum sensors. However, achieving spin squeezing has been challenging until now. Harvard physicists have recently described a new method to make spin squeezing more accessible, allowing for more precise measurements of certain signals at the expense of others.
Spin squeezing is a type of quantum entanglement that restricts the way a group of particles can fluctuate, resulting in more accurate measurements of specific observable signals. This concept can be likened to squeezing a balloon to increase height at the expense of width. By manipulating this uncertainty inherent in quantum measurements, researchers can reshape the sensitivity of measurements and achieve unprecedented precision. The ability to achieve spin squeezing has far-reaching implications for enhancing the performance of quantum sensors in various applications.
The Harvard team’s work builds upon a seminal 1993 paper that demonstrated the possibility of creating a spin-squeezed, entangled state through “all-to-all” interactions between atoms. These interactions, resembling a large Zoom meeting where every participant interacts with each other, facilitate the formation of quantum correlations essential for generating spin squeezing. However, the researchers have shown that it is actually easier to achieve quantum-enhanced spin squeezing than previously believed. Their new strategy involves leveraging the ingredients for spin squeezing present in common magnetic interactions, such as ferromagnetism, which is responsible for the magnetic properties of refrigerator magnets.
The researchers have outlined a novel approach for generating spin-squeezed entanglement, which they have validated through experiments in collaboration with scientists in France. By demonstrating that all-to-all interactions are not essential for achieving spin squeezing, the team has opened up new possibilities for creating more portable and efficient quantum sensors. This breakthrough may have significant implications for various applications, including biomedical imaging, atomic clocks, and other fields where precise measurements are crucial. The researchers are now working on implementing spin squeezing in quantum sensors using nitrogen-vacancy centers in diamond crystals, known for their suitability as quantum sensors.
This research has been supported by federal funding from agencies such as the Army Research Office, the Office of Naval Research, the Department of Energy, the Department of Defense, and the National Science Foundation. The collaboration between physicists at Harvard and their partners in France has paved the way for new innovations in the field of quantum sensing and measurement. By unlocking the potential of spin squeezing and making it more accessible, the researchers aim to inspire new approaches and applications in quantum science and engineering. The ability to harness quantum mechanics for more precise measurements and improved sensor performance has the potential to revolutionize various fields and drive advancements in technology.