Speed of quantum entanglement is measured, but it's too fast for humans to understand

In the past, events that took place in a flash were considered instantaneous. Yet modern experiments show that even when particles seem to shift in the blink of an eye, as with quantum entanglement, there are measurable intervals involved.

These findings spark questions about how electrons leave atoms or how entangled pairs form, opening avenues for precise control in various applications.

Measuring in attoseconds

Scientists once assumed that an electron remained in orbit around its nucleus and was then abruptly pulled away by a burst of light.

A similar assumption held for particles that collided and became entangled without any noticeable time span.

Today, attosecond-scale measurements allow researchers to scrutinize these events with remarkable detail.

By tracking processes once believed to be immediate, scientists can better understand interactions that may influence quantum communication and next-generation computing.

Understanding attoseconds – the basics

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.

Scientists use attoseconds to track the movements of electrons, which are some of the fastest things in the universe.

It’s like having a super high-speed camera for the quantum world, letting researchers watch events that were once way too fast to even imagine.

Time scale of quantum entanglement

“You could say that the particles have no individual properties; they only have common properties,” explains Prof. Joachim Burgdörfer from the Institute of Theoretical Physics at TU Wien.

“From a mathematical point of view, they belong firmly together, even if they are in two completely different places,”

In work published in Physical Review Letters, he and collaborators from China show how quantum entanglement can arise on ultrafast scales.

“We, on the other hand, are interested in something else – in finding out how this entanglement develops in the first place and which physical effects play a role on extremely short time scales,” says Prof. Iva Březinová.

Rather than focus on preserving quantum entanglement, her team explores the birth of this phenomenon.

How the study was done

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.”

Entangled at birth

The timing of the escaping electron links directly to the state of the electron left behind.

“This means that the birth time of the electron that flies away is not known in principle. You could say that the electron itself doesn’t know when it left the atom,” says Burgdörfer.

“It is in a quantum-physical superposition of different states. It has left the atom at both an earlier and a later point in time.”

If the electron that remains is in a higher-energy state, the departed electron likely left earlier. If the remaining electron is in a lower-energy state, that departure happened later.

On average, the difference is around 232 attoseconds, an incredibly short duration that the scientists believe can be tested in future experiments.

“We are already in talks with research teams who want to prove such ultrafast entanglements,” says Burgdörfer.

When an electron leaves an atom, it spreads out like a wave.

“It is a wave that spills out of the atom, so to speak – and that takes a certain amount of time,” says Březinová.

“It is precisely during this phase that the entanglement occurs, the effect of which can be measured later by observing the two electrons.”

Why does any of this matter?

Knowing how entanglement begins at such tiny time intervals can shape efforts in quantum-based encryption and computing.

By pinpointing the moment when two particles become linked, future technologies might harness these correlations more effectively.

Understanding the sequence of events could also help scientists refine methods of generating entangled pairs for secure data transfer.

Using entangled electrons

Many investigations have focused on preserving quantum entanglement. These results highlight that the creation of entanglement itself is equally important.

Observing how two electrons become correlated on timescales of a billionth of a billionth of a second opens possibilities for experimental work.

Researchers aim to verify these simulations in the lab, guided by the notion that quantum events unfold in ways once deemed too fast to measure.

Precision timing in the quantum realm

These studies suggest that quantum behavior is not purely immediate. Instead, even processes that seem abrupt have definable periods during which entanglement takes hold.

By zooming in on those intervals, scientists can gain insights into cause-and-effect in the quantum world. As laser technologies advance, the door opens to new measurements that capture the fleeting birth of entangled pairs.

This line of exploration may reshape how we design future systems that rely on the delicate interconnections of quantum particles.

It also underscores the importance of time-sensitive observations in unraveling complex interactions, suggesting that many so-called instantaneous events may hold untapped opportunities for quantum research.

As further collaborations emerge, these attosecond-scale findings could spark new methods to manipulate and measure entangled states, paving the way for innovative paths in science and technology.

Research teams worldwide are likely to build on these insights, examining how precise timing can refine quantum simulations and deepen understanding of particle interactions in next-generation devices.

The full study was published in the journal Physical Review Letters.

—–

Like what you read? Subscribe to our newsletter for engaging articles, exclusive content, and the latest updates.

Check us out on EarthSnap, a free app brought to you by Eric Ralls and Earth.com.

—–