Last Updated on June 14, 2025 by Sushanta Barman
In a latest development, physicists have demonstrated a quantum sensor capable of detecting subtle signals that classical sensors cannot. This innovative technology uses entangled particles to measure phases at multiple points simultaneously, achieving sensitivities previously considered impossible.
The research, led by Seongjin Hong from Yonsei University in Korea and Raphael C. Pooser from Oak Ridge National Laboratory (ORNL) in the United States, involved teams from ORNL, Yonsei University, Korea Institute of Science and Technology, and Korea Research Institute of Standards and Science. The results were published in the journal Physical Review Research.
The scientists developed a specialized quantum device known as a truncated SU(1,1) interferometer (tSU(1,1)). Unlike traditional sensors that measure signals individually, this device uses quantum entanglement, where two particles are interconnected such that the state of one instantly influences the state of the other, no matter the distance.
By employing “bright entangled twin beams,” the researchers could detect a linear combination of two separate phases with unprecedented precision, exceeding classical measurement limits—known as the “shot noise limit”—by approximately 1.7 dB. In practical terms, this means the sensor can pick out extremely weak signals from background noise, signals that would be indistinguishable to standard sensors.
“Using bright entangled twin beams, we theoretically and experimentally demonstrate the detection of a linear combination of two distributed phases beyond the shot noise limit,” the researchers noted in their publication.
The key innovation behind the tSU(1,1) interferometer lies in its simplicity and efficiency. Traditional quantum sensors require complex setups, whereas the tSU(1,1) configuration simplifies quantum sensing by using two local detectors instead of a more complex quantum interferometer.
In their experiment, the team generated bright quantum states by passing light through a rubidium vapor cell, creating pairs of photons with correlated properties. Each photon in a pair then encountered a separate phase shift. Finally, using homodyne detectors, the scientists precisely measured these shifts simultaneously, achieving superior sensitivity due to quantum correlations.
Beyond demonstrating the sensor’s immediate potential, the study outlines a clear pathway to expand this technology into large-scale networks. This could revolutionize fields requiring ultra-sensitive detection, such as gravitational wave astronomy, dark matter detection, and global synchronization of atomic clocks.
“Our results pave the way for developing quantum-enhanced sensor networks that can achieve an entanglement-enhanced sensitivity,” the authors concluded.
As this quantum sensor technology advances, it promises to unlock new capabilities in precision measurement, fundamentally transforming our approach to exploring and understanding the universe.
Read the full article: S. Hong et al., “Quantum-enhanced distributed phase sensing with a truncated SU(1,1) interferometer,” Phys. Rev. Research 7, 023231 (2025).
I am a senior research scholar in the Department of Physics at IIT Kanpur. My work focuses on ion-beam optics and matter-wave phenomena. I am also interested in emerging matter-wave technologies.
