Entangled Diamond Sensor Achieves 40-Fold Sensitivity for Nanoscale Magnetism

Researchers at Princeton University have developed a novel quantum sensor, built within lab-grown diamond, that significantly improves the observation of magnetic phenomena at the nanoscale. The findings, published in the journal Nature on November 26, 2025, detail a sensitivity approximately 40 times greater than previous measurement techniques, marking a methodological advance in condensed matter physics.

The core innovation relies on utilizing engineered defects known as nitrogen-vacancy (NV) centers. The team successfully implanted two NV centers in extremely close proximity—around 10 nanometers apart—to facilitate quantum entanglement between their respective electrons. This synchronous quantum interaction allows the sensor to isolate and measure magnetic signatures within inherently noisy fluctuations with unprecedented precision, overcoming limitations of earlier methods.

The development followed approximately five years of refinement, stemming from theoretical work initiated by Jared Rovny and led by Nathalie de Leon, an associate professor at Princeton. Their earlier research in 2022 examined correlations between non-entangled NV centers, which proved technically cumbersome. Professor de Leon noted that the new entangled approach simplifies the process, permitting a single, standard measurement instead of complex correlation detection.

The creation of these closely spaced, entangled NV centers required precise engineering: nitrogen molecules traveling at speeds exceeding 30,000 feet per second were projected onto the diamond surface. Controlling the collision energy ensured the atoms embedded at the exact required depth and separation.

This enhanced capability holds immediate relevance for probing materials where magnetic behavior at the sub-optical wavelength scale is crucial, including graphene and superconductors. Philip Kim, an experimental physicist at Harvard University specializing in low-dimensional materials, noted that this technique permits scientists to directly investigate real materials, a crucial step for understanding complex quantum behaviors that occur between the atomic level and the visible light wavelength.

The research, supported by funding from the Gordon and Betty Moore Foundation and the National Science Foundation, leverages quantum entanglement to transform the challenge of signal isolation in noise into a quantum advantage, offering a clearer window into the fundamental physics governing these advanced materials.