Princeton Researchers' Quantum Breakthrough Reveals Hidden Magnetic World with Diamond Defects
- MM24 News Desk
- 1 hour ago
- 3 min read
Credit: David Kelly Crow
Princeton University scientists have developed an entangled quantum sensor using paired defects in diamonds that provides roughly 40-times greater sensitivity than previous techniques, revealing previously invisible magnetic fluctuations at the nanoscale.
Led by Nathalie de Leon, associate professor of electrical and computer engineering, the breakthrough allows researchers to directly observe magnetic phenomena in real quantum materials like graphene and superconductors at length scales smaller than a wavelength of light.
The research, published November 27 in the journal Nature, represents a fundamental shift in how quantum sensors can operate. While diamond-based sensing methods have been developing for half a decade, the Princeton team's innovation came from engineering two defects extremely close together rather than treating them as individual sensors.
These nitrogen vacancy centers, implanted just 10 nanometers apart, interact through quantum entanglement—creating a system that acts like two eyes triangulating signals in the noisy magnetic background that conventional techniques cannot detect.
"What I realized is that if you entangled them, the presence or absence of a correlation sort of puts its fingerprint onto the system," said Jared Rovny, the study's lead author and a former Princeton Quantum Initiative postdoctoral fellow.
This fingerprint allows researchers to bypass previously cumbersome measurement problems, essentially getting the advantage of two sensors with the operational cost of using only one. The technique began as a theoretical project during COVID-19 lab restrictions before evolving into an experimental breakthrough.
The significance of this advancement lies in its ability to probe what physicists call the "mesoscale"—that crucial range between atomic dimensions and the wavelength of visible light where many of quantum materials' most interesting behaviors emerge.
"That range is, in fact, the length scale of interest," said Philip Kim, an experimental physicist at Harvard University who was not involved in the study but is now collaborating with de Leon. "A good range where one can understand a lot of interesting things," he added, noting that other techniques have been confined to carefully constructed arrays of atoms rather than real materials.
To create their revolutionary sensor, the researchers fired nitrogen molecules traveling more than 30 thousand feet per second at lab-grown diamonds about the size of large sea salt flakes. When these high-energy molecules strike the diamond's surface, they break apart, sending two nitrogen atoms hurtling into the diamond's crystalline structure to rest about 20 nanometers beneath the surface. The precise control over implantation depth and separation enables the quantum entanglement that makes the system so powerful.
The entangled sensors can now measure previously invisible quantities, such as how far an electron travels through a material before bouncing off another particle or the evolution of magnetic vortices that appear in superconducting materials under special conditions.
"You have this totally new kind of playground," de Leon stated. "You just can't see these things with traditional techniques." This new capability could accelerate understanding of superconductors that enable advanced medical imaging and form the basis of hoped-for technologies like lossless powerlines and levitating trains.
What began as pandemic-era theoretical curiosity has evolved into a powerful new experimental tool. "It was only after we started formalizing it that we realized how powerful it was," de Leon explained regarding their initial COVID-era project investigating magnetic noise correlations.
The research demonstrates how what might appear as a weakness in quantum systems—the interaction between closely spaced sensors—can be transformed into a decisive advantage, opening new windows into the hidden fluctuations of the quantum world.
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