quantum entanglement is the bonding of two particles or objects, even if they are 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 long-distance effect“, but its weirdness is what makes it so intriguing to scientists. In a Study 2021quant entanglement was observed and recorded directly at the macroscopic scale – a scale much larger than the subatomic particles normally associated with entanglement.
The dimensions are still tiny from our point of view – the experiments involved two tiny aluminum drums a fifth the width of a human hair – but in the realm of quantum physics they are absolutely huge.
“If you analyze the position and momentum data for the two drums independently, they both just look hot”, said the physicist John Teufelfrom the National Institute of Standards and Technology (NIST) in the US, last year.
“But when we look at them together, we can see that what appears to be random movement of one drum is strongly correlated with the other in a way that is only possible through quantum entanglement.”
While there is nothing to say that quantum entanglement cannot occur in macroscopic objects, it was previously thought that the effects would be imperceptible at larger scales – or that perhaps the macroscopic scale obeys different rules.
Recent research suggests that is not the case. In fact, the same quantum rules apply here and can actually be seen. The researchers used microwave photons to vibrate the tiny drum membranes, keeping them in a synchronized state in terms of position and speed.
To avoid outside interference, a common problem with quantum states, the drums were cooled, entangled and measured in separate stages while inside a cryogenically cooled enclosure. The states of the drums are then encoded in a reflected microwave field that works in a similar way 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 derived, and the entanglement was generated in a deterministic, non-random way.
And a related but separate series of experimentsResearchers also 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 the two drumheads simultaneously.
“In our work, the eardrums show a collective quantum motion”, said physicist Laure Mercier de Lepinay, from Aalto University in Finland. “The drums vibrate in opposite phase to each other, so that when one of them is in one end position of the vibration cycle, the other is in the opposite position at the same time.”
“In this situation, if the two drums are treated as one quantum mechanical entity, the quantum uncertainty of the drum motion is removed.”
What sets these headlines apart is that word gets around Heisenberg’s uncertainty principle – the idea that position and momentum cannot be measured perfectly at the same time. The principle states that the recording of one of the two measurements disturbs the other through a process called “interference”. quantum feedback.
In addition to supporting the other study by demonstrating macroscopic quantum entanglement, this particular research paper uses this entanglement to avoid quantum repercussions – essentially examining the boundary between classical physics (where the uncertainty principle applies) and quantum physics (where it applies now). not shine).
One of the potential future applications of both findings is in quantum networks – the ability to manipulate and entangle objects at the macroscopic level so that they can power next-generation communication networks.
“Aside from practical applications, these experiments are about how far experiments can push the observation of definite quantum phenomena into the macroscopic domain,” write physicists Hoi-Kwan Lau and Aashish Clerk, who were not involved in the studies, in a commentary on the research results published at the time.
A version of this article was first published in May 2021.