Researchers at Tohoku University have developed a method to enhance quantum sensors by connecting superconducting qubits in optimized networks, potentially detecting faint signals from dark matter. This approach outperforms traditional methods even under realistic noise conditions. The findings could extend to applications in radar, MRI, and navigation technologies.
Detecting dark matter, the invisible substance believed to hold galaxies together, remains a major challenge in physics. While it cannot be directly observed, scientists suspect it leaves subtle traces that advanced quantum technologies might capture. A team from Tohoku University has introduced a strategy to boost the sensitivity of quantum sensors by linking them in carefully designed networks.
The research focuses on superconducting qubits, tiny electronic circuits maintained at extremely low temperatures. Typically used in quantum computers, these qubits serve here as ultrasensitive detectors. By organizing them into patterns like rings, lines, stars, or fully connected structures, the networks amplify weak signals more effectively than a single sensor could.
The team tested systems with four and nine qubits, employing variational quantum metrology—similar to training a machine-learning algorithm—to optimize quantum state preparation and measurement. They also applied Bayesian estimation to mitigate noise, akin to sharpening a blurred image. Even with added realistic noise, the optimized networks surpassed conventional approaches.
"Our goal was to figure out how to organize and fine-tune quantum sensors so they can detect dark matter more reliably," said Dr. Le Bin Ho, the study's lead author. "The network structure plays a key role in enhancing sensitivity, and we've shown it can be done using relatively simple circuits."
Beyond dark matter detection, the technique holds promise for quantum radar, gravitational wave sensing, precise timekeeping, improved GPS accuracy, enhanced MRI scans, and mapping underground structures. "This research shows that carefully designed quantum networks can push the boundaries of what is possible in precision measurement," Dr. Ho added. "It opens the door to using quantum sensors not just in laboratories, but in real-world tools that require extreme sensitivity."
The team plans to scale up to larger networks and improve noise resilience. Their work, co-authored with Adriel I. Santoso, was published in Physical Review D on October 1, 2025.