Quantum entanglement now directly observed at the macroscopic scale: Science Alert

Quantum entanglement The binding together of two particles or objects, even though they may be far apart – their respective properties are linked in a way that is not possible according to the laws of classical physics.

This is a strange phenomenon that Einstein described.”Spooky action in the distance“, but its strangeness is what makes it so attractive to scientists 2021 studyquantum trap were 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 experiment involved two tiny aluminum drums about one-fifth the width of a human hair – but in terms of quantum physics they are absolutely enormous.

“If you analyze the position and speed data of the two drums independently, they each look just hot,” says physicist John Teufelfrom the US National Institute of Standards and Technology (NIST), last year.

“But looking at them together, we see that what appears to be the random motion of one drum is highly correlated with the other, in a way that is only possible through Quantum entanglement“

While this is not to say that quantum entanglement cannot occur with macroscopic matter, it was previously thought that the effects were not noticeable on large scales – or perhaps the macroscopic scale was governed by other laws.

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

To prevent outside interference, a common problem in quantum states, the drums were cooled, clamped, and measured in separate phases while inside a cryogenically cooled enclosure. The states of the drums are then encoded in a reflected microwave field that works similarly to radar.

Previous research also reported on macroscopic quantum entanglement, but the 2021 study went further: all the necessary measurements were recorded rather than guessed, and the entanglement was generated in a deterministic, non-random way.

A Related but separate series of testsResearchers working with macroscopic drums (or oscillators) in a state of quantum entanglement have shown how it is possible to measure the position and momentum of two drumheads simultaneously.

“In our work, the drumheads exhibit a collective quantum motion,” Says physicist Laure Mercier de Lepinefrom Aalto University, Finland. “The drums vibrate in opposite phases to each other, such that one of them is in the last position of the vibration cycle, while the other is in the opposite position at the same time.”

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

It almost gets to what makes this headline news Heisenberg’s uncertainty principle – The idea that position and velocity cannot be measured perfectly at the same time. The principle states that the recording of one measurement will interfere with another through a process Quantum back action.

In addition to backing up other research in demonstrating macroscopic quantum entanglement, this particular body of research uses that entanglement to avoid quantum back action – essentially investigating the line between classical physics (where the uncertainty principle applies) and quantum physics (where it no longer exists). not visible).

One of the possible future applications of both sets of results is quantum networks – capable of manipulating and entangling objects on a macroscopic scale so that they can power the next generation of communication networks.

“In addition to practical applications, these experiments show how far experiments in macroscopic states can clearly push the observation of quantum phenomena,” wrote physicists Hoi-Quan Lau and Ashish Clark, who were not involved in the research. A commentary on research published at the time.

Both the first And the second The study was published science.

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