Every second, terabytes of data—enough to download thousands of movies—travel through fiber-optic cables as light.

These cables act like super-fast highways, moving information around the globe.

But when this data reaches a data center, it needs a “traffic light” to guide it to the right destination.

These traffic lights are called photonic switches, and they play a critical role in keeping the internet and other digital services running smoothly.

Until now, photonic switches have faced a big problem: a tradeoff between size and speed. Larger switches can handle more data at higher speeds but take up more space, use more energy, and cost more.

Smaller switches save on space and energy but can’t keep up with the growing demand for faster, more powerful networks.

A team of researchers at the University of Pennsylvania has now solved this problem. In a new study published in Nature Photonics, the team unveiled a photonic switch that is both small and incredibly fast.

Each unit of this switch is just 85 by 85 micrometers—smaller than a grain of salt. Despite its tiny size, it can redirect light signals faster than ever before, breaking the traditional size-speed limits.

The secret behind this new switch lies in advanced quantum physics, specifically a field called non-Hermitian physics. This branch of physics explores how systems behave in unique ways, giving researchers more control over the flow of light.

The switch can adjust the properties of the material it’s made from to guide light signals precisely to the correct “exit” on the information highway. This allows it to redirect data in trillionths of a second—about a billion times faster than the blink of an eye—while using very little power.

“We’ve created a system that combines speed and size in a way that’s never been done before,” explains Shuang Wu, a co-author of the study.

The researchers used silicon as one of the key materials in their switch. Silicon is cheap, widely available, and already used in manufacturing chips for computers and smartphones. By designing the switch to work with silicon, the team made it easier to mass-produce and integrate into existing technology.

On top of the silicon layer, they added a special semiconductor material called Indium Gallium Arsenide Phosphide (InGaAsP). This material is excellent for manipulating infrared light, which is commonly used in undersea fiber-optic cables. Combining these materials was a challenge, requiring nanometer-level precision during assembly. “It’s like making a very delicate sandwich,” says Xilin Feng, the study’s lead author.

The new switch could transform data centers, the backbone of the internet. Faster, smaller, and more efficient switches like this one could help companies handle increasing amounts of data more effectively. This means better streaming, faster downloads, and smarter AI applications for users worldwide.

“Data can only move as fast as we can control it,” says Liang Feng, the senior author of the study. “Our switch has a speed limit of just 100 picoseconds, making it one of the fastest systems ever developed.”

This breakthrough is a big step toward creating faster, more efficient networks to meet the growing demands of our digital world.