Light Instead of Wires: A Quantum Computer on Fiber Optics express
A massive refrigerator the size of a wardrobe hums, maintaining an interior colder than outer space. At its heart lies a silicon chip with tiny superconducting loops — qubits. But to make the chip work, dozens of thick copper cables snake from room temperature down to it. Each cable acts like an open refrigerator door: it conducts heat and distorts delicate quantum signals. Engineers have long sought a way to remove these "doors" without losing control.
In the new work, the scientists replaced the copper bundles with optical fibers as thin as spider silk. Light travels through them with almost no loss and carries no heat. At the cold end, right next to the chip, they placed miniature receivers, photodiodes, that convert light flashes back into electrical commands. It's like running a silent light pipe into the room instead of a buzzing fan. With this setup, they managed not just to flip a simple qubit but to conduct an entire "orchestra"—photonic states inside a resonator. There, like in a music box, you can create a precisely defined number of light quanta — up to ten in a single cell.
The key trick is that a light beam carries many channels at once. A single fiber can simultaneously send signals for different qubits, like a highway with a dozen lanes. This solves the scaling problem: when qubits number in the thousands rather than dozens, there will simply be no place to plug in copper cables. The optical "web" remains light and compact. Moreover, it becomes possible to spread quantum processors across different buildings or even cities, linking them with light into a unified computing cluster — a distributed quantum data center.
Thus, the cold abyss inside the cryostat ceases to be an isolated island. A light bridge connects it to the ordinary world without disturbing the fragile silence where quantum computations are born.
Original abstract
as written by the authors arXiv:2512.10706
Superconducting quantum computing has the potential to revolutionize computational capabilities. However, scaling up large quantum processors is limited by the cumbersome and heat-conductive electronic cables that connect room-temperature control electronics to quantum processors, leading to significant signal attenuation. Optical fibers provide a promising solution, but their use has been restricted to controlling simple two-level quantum systems over short distances. Here, we demonstrate optical control of a bosonic quantum processor, achieving universal operations on the joint Hilbert space of a transmon qubit and a storage cavity. Using an array of cryogenic fiber-integrated uni-traveling-carrier photodiodes, we prepare Fock states containing up to ten photons. Additionally, remote control of bosonic modes over a transmission distance of 15 km has been achieved, with fidelities exceeding 95%. The combination of high-dimensional quantum control, multi-channel operation, and long-distance transmission addresses the key requirements for scaling superconducting quantum computers and enables architectures for distributed quantum data centers.
A single optical fiber as thin as a human hair can transmit more data than a kilogram of copper wires. At the same time, it barely conducts heat — unlike metal, which acts as a bridge for heat from the outside.
In the series "The Expanse," ships communicate via laser beams over vast distances. Here, the same principle applies, but on a microscopic scale: light carries not voices but instructions for a quantum processor.