Scientists Measure Quantum Entanglement Speed for First Time in Attosecond Breakthrough

Revolutionary Timing Discovery

For decades, quantum entanglement has been considered instantaneous—a phenomenon where two particles become mysteriously connected across vast distances with no apparent delay. But scientists from TU Wien and China have now measured these fleeting moments using advanced computer simulations, managing to peek into processes that happen on attosecond timescales – a billionth of a billionth of a second . Processes thought to happen instantaneously, like quantum entanglement, are now being directly measured in the tiniest fractions of a second – attoseconds .

The research team, led by Prof. Joachim Burgdörfer and Prof. Iva Březinová, discovered something remarkable: if the remaining electron is in a state of higher energy, then the electron that flew away was more likely to have been torn out at an early point in time; if the remaining electron is in a state of lower energy, then the 'birth time' of the free electron that flew away was likely later—on average around 232 attoseconds . To put this in perspective, an attosecond is an insanely tiny slice of time – just one-quintillionth of a second (that's a 1 followed by 18 zeros). To put it in perspective, light can only travel about the width of a human hair in that time .

How They Cracked the Quantum Code

The experimental approach was ingenious. Their approach involves intense, high-frequency laser pulses striking atoms. The first electron is ejected from the atom and propelled away. Under certain conditions, the second electron also absorbs energy and moves to a higher orbital . "We can show that these two electrons are now quantum entangled," says Burgdörfer. "You can only analyze them together—and you can perform a measurement on one of the electrons and learn something about the other electron at the same time."

The key insight came from understanding that entanglement isn't truly instantaneous. "The electron doesn't just jump out of the atom. It is a wave that spills out of the atom, so to speak – and that takes a certain amount of time," Iva Březinová, an assistant professor at the Institute of Theoretical Physics at TU Wien, said. "It is precisely during this phase that the entanglement occurs, the effect of which can then be precisely measured later by observing the two electrons."

The team has devised a measurement protocol combining two different laser beams to capture this elusive timing . This breakthrough challenges the fundamental assumption that quantum effects happen without any measurable duration.

Real-World Impact

These findings extend far beyond academic curiosity. Understanding how entanglement forms could have big implications for quantum technologies like cryptography and computing. Instead of just trying to maintain entanglement, scientists can now study its very inception. This could lead to new ways of controlling quantum systems and enhancing the security of quantum communications .

A better understanding of entanglement could enhance the technologies of tomorrow, particularly for secure data transfer through quantum encryption . The ability to control quantum entanglement at such precise timescales opens possibilities for quantum computers that could operate at previously unimaginable speeds.

The Future of Quantum Science

"We are already in talks with research teams who want to prove such ultrafast entanglements," Burgdörfer shares . They're already collaborating with other researchers eager to test and observe these ultrafast entanglements in the lab . The transition from computer simulations to real laboratory experiments represents the next frontier in quantum physics.

This research fundamentally changes how we think about the quantum world. The work shows that it is not enough to regard quantum effects as 'instantaneous'. Important correlations only become visible when one manages to resolve the ultra-short time scales of these effects . As quantum technologies mature from laboratory curiosities to practical applications, understanding these ultrafast processes will be crucial for developing the secure communications and powerful computers of tomorrow.