In a groundbreaking experiment that’s pushing the frontiers of physics, researchers have, for the first time, measured just how fast quantum entanglement happens—and the results are nothing short of astonishing. Long thought to be instantaneous, quantum entanglement describes how two particles become so deeply linked that the state of one instantly affects the other, no matter how far apart they are. But now, thanks to mind-bogglingly precise techniques, scientists have put an actual time scale on this mysterious process.

Published in Physical Review Letters, the new study shows entanglement unfolding over just 232 attoseconds. For some perspective, light travels only the width of a human hair in that time. Using tools like attosecond streaking and the RABBIT technique (which helps track ultrafast electron dynamics), the team led by Prof. Joachim Burgdörfer and Prof. Iva Březinová managed to probe the quantum realm with unprecedented clarity. They fired high-frequency lasers to entangle electrons and tracked their dance in exquisite detail, finding that classical physics simply doesn’t apply in this bizarre subatomic world.

What makes this even more exciting is the promise it holds for the future. By understanding entanglement’s timing, scientists could develop quantum encryption so secure it’s virtually hack-proof, or design ultra-fast quantum computers that blow today’s tech out of the water. As Prof. Březinová put it, cracking the speed of entanglement could be the key to rewriting the rules of data security and computation forever.