Quantum entanglement has now been directly observed at the macroscopic scale: ScienceAlert

Quantum entanglement has now been directly observed at the macroscopic scale: ScienceAlert
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Quantum entanglement is the binding of two particles or objects even though they are far apart – their respective properties are connected in a way that is impossible according to the rules of classical physics.

It is a strange phenomenon that Einstein described as “scary action in the distance“, but its strangeness is what makes it so attractive to scientists. a 2021 educationquant entanglement directly observed and recorded at the macroscopic scale—a scale much larger than the subatomic particles typically associated with entanglement.

The dimensions involved are still very small from our perspective – the experiments involved two tiny aluminum drums about one-fifth the width of a human hair – but in the realm of quantum physics they are absolutely huge.

two metal drums
Macroscopic mechanical drums. (J. Teufel/NIST)

“If you analyze the position and momentum data for the two drums independently, each of them just looks hot,” said physicist John Teufelfrom the National Institute of Standards and Technology (NIST) in the United States, last year.

“But when we look at them together, we can see that what looks like the random movement of one drum is highly correlated with the other, only possible in this way. quantum entanglement.”

While there’s nothing to say that quantum entanglement can’t happen with macroscopic objects, it was previously thought that the effects weren’t noticeable on larger scales, or perhaps governed by a different set of rules than the macroscopic scale.

Recent studies show that this is not the case. In fact, the same quantum rules apply here and can actually be seen. Using microwave photons, the researchers vibrated tiny drum membranes and kept them synchronized in terms of position and speed.

To avoid extraneous interference, a common problem with quantum states, the drums were cooled, oscillated, and measured in separate stages while inside a cryogenically cooled enclosure. The positions of the drums are then encoded in the reflected microwave field, which works similar to radar.

previous studies also reported macroscopic quantum entanglement, but the 2021 study went further: All necessary measurements were recorded instead of inferred, and entanglement was created in a deterministic, non-random way.

into series of related but separate experiencesthe researchers also showed how it is possible to simultaneously measure the position and velocity of two drum heads operating with macroscopic drums (or oscillators) in a state of quantum entanglement.

“In our work, drumheads exhibit collective quantum motion” said physicist Laure Mercier de Lepinay, from Aalto University, Finland. “The drums vibrate in opposite phase to each other, so that when one of them is in the last position of the vibration cycle, the other is in the opposite position at the same time.”

“In this case, the quantum uncertainty of the motion of the drums is canceled if the two drums are treated as one quantum-mechanical entity.”

What makes this headline news is that it’s around Heisenberg uncertainty principle – the idea that position and momentum cannot be perfectly measured at the same time. The principle states that recording either measurement will interfere with the other through the called process quantum backward motion.

In addition to supporting other research to demonstrate macroscopic quantum entanglement, this particular piece of research uses this entanglement to prevent quantum recoil—essentially exploring the line between classical physics (where the Uncertainty Principle applies) and quantum physics (where it doesn’t). ‘t) appears).

One potential future application of both sets of findings is in quantum networks—manipulating and entangling objects on a macroscopic scale so they can power next-generation communication networks.

“Apart from practical applications, these experiments address how far experiments in the macroscopic realm can push the observation of clear quantum phenomena,” write physicists Hoi-Kwan Lau and Aashish Clerk, who were not involved in the research. interpretation of the study published at the time.

Also first and second study was published Science.

A version of this article was first published in May 2021.

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