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 it is the union of two particles or objects, although they may be far apart; their respective properties are linked in a way that is not possible according to the rules of classical physics.

It is a strange phenomenon that Einstein described as “spooky action at a distance“, but its rarity is what makes it so fascinating to scientists. In a study 2021quantum tangle it was directly observed and recorded on the macroscopic scale, a scale much larger than the subatomic particles normally associated with entanglement.

The dimensions involved are still very small from our perspective – the experiments involved two small aluminum drums 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 of the two drums independently, each of them just looks hot,” said physicist John Teufelfrom the US National Institute of Standards and Technology (NIST) last year.

“But looking at them together, we can see that what looks like random movement of one drum is highly correlated to the other, in a way only possible through quantum entanglement.”

While there is nothing to say that quantum entanglement cannot occur with macroscopic objects, before this it was thought that the effects were not noticeable at larger scales, or perhaps that the macroscopic scale was governed by another set of rules.

Recent research suggests that is not the case. In fact, the same quantum rules also apply here and can be seen as well. The researchers vibrated the tiny membranes of the drum using microwave photons and kept them in a synchronized state in terms of their position and speeds.

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

Previous studies had also reported on macroscopic quantum entanglement, but the 2021 research went further: all the necessary measurements were recorded rather than inferred, and the entanglement was generated deterministically rather than randomly.

in a series of related but separate experimentsResearchers also working with macroscopic drums (or oscillators) in a quantum entangled state have shown how it is possible to measure the position and momentum of the two heads at the same time.

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

“In this situation, the quantum uncertainty of the drums’ motion cancels out if the two drums are treated as one quantum mechanical entity.”

What makes this headline news is that it spreads Heisenberg uncertainty principle – the idea that position and momentum cannot be measured perfectly at the same time. The principle states that recording either measure will interfere with the other through a process called quantum back action.

In addition to supporting the other study by demonstrating macroscopic quantum entanglement, this particular research uses that entanglement to prevent quantum reverse action, essentially probing the line between classical physics (where the Uncertainty Principle applies) and quantum physics (where does not apply now). not seem).

One of the possible future applications of both sets of findings is in quantum networks: being able to manipulate and entangle objects on a macroscopic scale so that they can power next-generation communication networks.

“In addition to practical applications, these experiments address to what extent at the macroscopic level the experiments can further the observation of distinctly quantum phenomena,” write physicists Hoi-Kwan Lau and Aashish Clerk, who were not involved in the studies, in a comment on research published at the time.

Both of them first and the second study were published in Sciences.

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

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