Figure 1: An artistic representation of nonreciprocal quantum synchronization. RIKEN researchers have proposed a novel approach for the nonreciprocal quantum synchronization of phonons that is resilient against imperfections and noise. © 2026 RIKEN Center for Quantum Computing
A novel approach for realizing the one-way quantum synchronization of phonons has been proposed by three theoretical physicists at RIKEN1. Importantly, this method is remarkably resilient against practical challenges such as imperfections and environmental noise.
Many devices use components that act as one-way streets, allowing particles to travel in one direction, but almost not at all in the opposite one. These so-called nonreciprocal components are widely used in microwave and light-based systems for things such as controlling signal flow and preventing reflections.
"Nonreciprocal components enable signals to travel along desired paths, whereas they are strongly attenuated in the opposite direction," notes Franco Nori of the RIKEN Center for Quantum Computing (RQC). "This ability finds applications ranging from signal processing to invisible cloaking."
One nonreciprocal phenomenon that physicists are eager to realize in the lab is nonreciprocal quantum synchronization, where two quantum systems synchronize with each other in one direction, but not in the reverse direction.
However, it has been challenging to realize a practical method for achieving nonreciprocal quantum synchronization, with previously proposed schemes suffering from various practical limitations.
"Practical quantum technologies face critical challenges from random fabrication imperfections and environmental noise," notes Adam Miranowicz, also of RQC. "These factors profoundly suppress-or even completely destroy-quantum resources in conventional approaches."
Now, in a theoretical study, Nori, Miranowicz and Deng-Gao Lai have come up with a method for achieving the nonreciprocal quantum synchronization of sound particles, or phonons, that overcomes these limitations.
"This development establishes a new foundation for generating fragile-to-robust nonreciprocal quantum resources with future practical applicability," says Nori.
The method that the researchers developed is a synergistic one that exploits two different quantum effects. This approach synchronizes phonons when light or a magnetic field is applied from one direction, but not when it is applied from the opposite direction.
The trio was surprised by the unexpected robustness of their approach. "We were thrilled to discover that quantum synchronization persists even in the presence of substantial imperfections and noise," says Lai. "Previously, this was thought to be impossible without employing complex protection schemes."
The researchers believe that this work opens new avenues for realizing practical quantum technologies, and they intend to take the research further.
"By enabling robust nonreciprocal quantum synchronization, our research paves the way for realizing more reliable quantum processors and protected quantum resources," comments Lai. "We're now planning to explore applications in quantum networking and error-resilient quantum information processing."
Franco Nori (first row, second from the right), Adam Miranowicz (first row, first on the left), Deng-Gao Lai (second row, first on the left), and their team, as well as many visiting researchers, at the RIKEN Center for Quantum Computing. © 2026 RIKEN
