A team led by researchers from Delft University of Technology has made a groundbreaking achievement in the arena of quantum technology. Simon Gröblacher directs this novel initiative. Their most recent work involved the development of a single-phonon directional coupler, which is pioneering. This new, groundbreaking device is intended to more quickly and efficiently transmit quantum information. This achievement might open the door to hybrid quantum networks, extending the power of quantum computing and communications systems.
The team built this novel coupler out of silicon with four ports that act as two separate inputs and two outputs. This setup is similar to a well-known optical directional coupler. Specifically, it allows for fast controlled manipulation of phonons, which are the quantum vibrations that form the basis for processing information in the quantum realm. According to Gröblacher, this coupler functions as an intersection within a quantum “mail delivery system.” With this configuration, quantum messages can be routed very precisely.
The real world ramifications of this device go well beyond academic curiosity. Gröblacher is enthusiastic about the exciting prospects that this technology could bring. He thinks it could unlock a whole class of quantum experiments and lead to ultra-sensitive mechanical sensors that are extremely miniaturized. Once production was achieved, the research group carefully controlled the energy distribution within a coherent phonon wave packet. They mapped how this energy traveled between the two output cavities over time and through several round trips, confirming the coupler’s efficiency.
Understanding the Single-Phonon Directional Coupler
The invention is a major breakthrough in quantum technology. This device provides a way to route and manipulate individual phonons on-disk. This skill is necessary to shuttle quantum information between disparate quantum platforms. This innovative work opens up new and fundamental possibilities for hybrid quantum systems.
Gröblacher elaborates on the importance of this technology: “The ability to route and manipulate single phonons on a chip is key to transferring quantum information between different types of quantum systems and unlocking the potential of hybrid quantum systems.” Such capability may result in the development of smaller scale and more agile quantum devices and networks.
Gröblacher is confident that this new device will transform science. He suggests its potential impact would be similar to that of optical devices today. He asserts, “We expect that the new device will be as important as the optical counterpart is in modern science.”
Potential Applications and Future Prospects
The potential applications of the single-phonon directional coupler reach far beyond the lab, especially when looking at its impact on quantum computing and information processing. Gröblacher highlights its versatility, stating that “our device could enable microscopic on-chip routers and splitters that link superconducting qubits, which are often used for fast quantum calculations, with spin-based systems, which are good for storing quantum information for longer periods.”
This capability, which is the first of its kind, unlocks unprecedented opportunities for research and development in quantum technologies. Developing hybridised systems that bring together the best of articulate quantum processors could change the game for quantum information processing. This relatively simple innovation would drastically improve the efficiency, efficacy, and scalability of our systems.
Further, the coupler’s design provides an opportunity to use it as an interface to connect otherwise incompatible quantum systems. As Gröblacher explains, “Phonons can serve as on-chip quantum messages that connect very different quantum systems, enabling hybrid networks and new ways to process quantum information in a compact, scalable format.”
Research Publication and Impact
These results and ongoing future studies have been recorded in a publication, “A single-phonon directional coupler,” appearing in Optica Quantum. The study is accessible through its DOI: 10.1364/opticaq.569727. The work has been reported in an article titled “Chip-based phonon splitter brings hybrid quantum networks closer to reality,” which was retrieved on October 6, 2025, from https://phys.org/news/2025-10-chip-based-phonon-splitter-hybrid.html.
This study goes a long way in helping the scientific community understand how to create more useful phononic devices. It moves us towards the realization of practical hybrid quantum networks.