Researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences have developed a photon router that could enable superconducting quantum networks. The breakthrough device, which resembles a paper clip, bridges the energy gap between microwave and optical photons, allowing control of microwave qubits with signals generated far away.
The team created a microwave-optical quantum transducer, a device designed for quantum processing systems using superconducting microwave qubits as its smallest units of operation. This device is the first to demonstrate control of a superconducting qubit using only light.
The researchers say that optical photons are ideal carriers of information due to their low loss and high bandwidth. However, one major bottleneck in deploying superconducting microwave qubit platforms is the extremely low temperatures required for operation.
To overcome this challenge, the transducer uses microwave qubits to perform quantum operations, but to use optical photons as efficient interfaces. The device works by linking a microwave resonator with two optical resonators, allowing back-and-forth exchange of energy.
The breakthrough brings us closer to a world with superconducting quantum processors connected by low-loss, high-powered optical networks. Future research aims to develop reliable generation and distribution of entanglement between microwave qubits using light.
Source: https://phys.org/news/2025-04-router-photons-transducer-enable-superconducting.html