Entangled in Quantum Networks

Tribbles, No; Entanglement, Yes

You’ve heard of quantum entanglement, if only in the context of Star Trekian jargon-laden scif-fi expositions like those spouted by Lieutenant Commander Data.

Unlike tribbles and Klingons, however, quantum entanglement is unnervingly real. That is, you have two or more particles that are tangled up in such a way that, even when they’re separated by a long distance, the quantum state of one of them is somehow effected by or reflected in the states of the others.

Weird and a kind of spooky, right? Which is why Einstein dubbed it, with a degree of mockery since he wasn’t quite buying the reality of it, “spooky action at a distance.” Since then, of course, entanglement has been tested many times. At this point, it’s no longer a theory but a practical fact, spooky or no.

Entangling the Big, Hairy Stuff

But what scientists have not done as often is apply quantum entanglement to big stuff: you know, like your hair.

Some recent experiments have worked with two aluminum “drums” that are huge by comparison to subatomic particles: the size of a fifth of a human hair. That is, 20 micrometers wide by 14 micrometers long and 100 nanometers thick, weighing in a whopping 70 picograms (okay, so small, but still macroscopic).

Credit: J. Teufel/NIST

ScienceAlert describes the process as follows: “Researchers vibrated the tiny drum membranes using microwave photons and kept them in a synchronized state in terms of their position and velocities. To prevent outside interference, a common problem with quantum states, the drums were cooled, entangled, and measured in separate stages while inside a cryogenically chilled enclosure. The states of the drums are then encoded in a reflected microwave field that works in a similar way to radar.”

The experimenters got the drums to vibrate in an opposite phase to one another, indicating a collective quantum motion, said physicist Laure Mercier de Lepinay, from Aalto University in Finland.

“To verify that entanglement is present, we do a statistical test called an ‘entanglement witness,’’’ NIST theorist Scott Glancy said. “We observe correlations between the drums’ positions and momentums, and if those correlations are stronger than can be produced by classical physics, we know the drums must have been entangled.”

John Teufel, a physicist at NIST and a co-author of one of the papers on this topic, said, “These two drums don’t talk to each other at all, mechanically. The microwaves serve as the intermediary that lets them talk to each other. And the hard part is to make sure they talk to each other strongly without anybody else in the universe getting information about them.”

So, Take That, Heisenberg!

This is clearly cool on multiple levels. First, of course, quantum entanglement at the macroscopic level! What? Is that a thing?

Why, yes. Yes it is. In fact, this isn’t the first time it’s happened.

But, second, this time around physicists have (sort of) gotten around the impossibility of measuring both position and momentum when investigating quantum states.

Glancy states, “The radar signals measure position and momentum simultaneously, but the Heisenberg uncertainty principle says that this can’t be done with perfect accuracy. Therefore, we pay a cost of extra randomness in our measurements. We manage that uncertainty by collecting a large data set and correcting for the uncertainty during our statistical analysis.”

Tap into Your Quantum Network

The concept of a quantum network is, of course, like catnip to people interested in reticula. In the future such networks could “facilitate the transmission of information in the form of quantum bits, also called qubits, between physically separated quantum processors.”

For now, these networks are mostly fiction, but they potentially have a lot of communication and computation applications. One is that they become the backbone of unhackable computer networks. In fact, Mara Johnson-Groh writes that it’s already the case that “basic quantum communications called quantum key distributions are helping secure transmissions made over short distances.”

Johnson-Groh predicts that “quantum networks will be important in scientific sensing first” and highlights the idea of optical telescopes from all over the world connected via a quantum network. The goal would be dramatically improving resolution, resulting in “ground-breaking discoveries about the habitability of nearby planets, dark matter and the expansion of the universe.” 

The Entangled Reticulum

There’s something poetic about using a quantum network in order to more clearly see the Reticulum constellation (aka, the net) among other things.

But the poetry runs deeper than that. Quantum entanglement is said to occur naturally. Assuming this to be true, I can imagine countless entangled particles streaming off in opposite directions through the universe, encompassing distances that would put the length of a single galaxy to shame.

This would mean large portions of our universe are entangled. The spin of one photon–zinging at lightspeed well beyond the ken of our greatest telescopes–could be entangled with a local photon that happens to meet your retina on a starry night. Thus, the universe is an infinitely complex reticulum of star stuff lighting our consciousness with instantaneous connections from unimaginable distances.

Featured image: Star-forming region called NGC 3324 in the Carina Nebula. Captured in infrared light by NASA’s new James Webb Space Telescope, this image reveals for the first time previously invisible areas of star birth.