Research group detects a quantum entanglement wave for the first time

Can this be used for network communication? As in, two devices connected at any distance using quantum entanglement, no wires nor unobstructed antenna connection needed (still light speed delay of course)

marginalia_nu• 3 years ago

No. [1]

[1] https://en.m.wikipedia.org/wiki/No-communication_theorem

winternewt• 3 years ago

I thought this referred to some kind of wave that is emitted when two particles are entangled (or alternatively a wave that communicates information between two entangled particles), which goes against my lay man's intuition about how quantum physics works.

After reading my best understanding is that entangled particles can act as a single wave function and that they have detected when this wave interacts with other things.

gus_massa• 3 years ago

Good research, bad title.

This is not a long distance entanglement. As before/always, you can't put one electron on Earth and another entangled electron on the Moon and use this for FTL communication, or put a detector in the middle and see a passing wave of entanglement or unentaglement or something. So nothing changed.

The idea is that two electrons can have the same spin or the oposite spin [1]. If they have oposite spin we call it a "singlet", and if they have the same spin we call it a "triplet".

In this case both electrons are inside a molecule, so they are very close. Most of the times, the electrons will have the oposite spin. Moreover this molecules have a lot of pairs of electrons with the same spin that we are hiding under the rug. This particular molecule, have a pair of unpaired electrons, and most of the times they are a "singlet" but sometimes a "triplet".

I would not call these electrons "entangled". I reserve the word "entangled" for "long distance entanglement". For short distance like inside the same molecule I'd use "correlated" or "coupled". The abstract algebra is the same in all cases, so it's a problem of how we call it. But short distance effects are too commons, the weird unexpected cases are the "long distance entanglement.

In this case, it's easier to do the calculations if you ignore all the singlets and imagine the triplets are pair of perfectly glue together electrons and watch they move as as a single "particle". So we call the idealized magically glued pair of electrons a "quasiparticle". In this case, since it's a triplet moving around the call it a "triplon" [2].

They made a chain of molecules. All of them had singlets that we are ignoring. Then they flipped of them to create a "triplon" and used a tunnel microscope to "watch" how the "triplon" moved from molecule to molecule. [3]

[1] Some technical details are intententionaly missing.

[2] The quasiperticles are very common. The most famous example are the holes in a semiconductor.

[3] I think they measure the dispersion relation, not a isolated triplon moving, but I don't understand all the details. So perhaps they measure waves made of trilons.

egberts1• 3 years ago

We witness quantum entanglement everyday.

- Photosynthesis

- Photoelectric effect

- electrical wiring

- cellular mitosis

- Van der Wahl force

Research group detects a quantum entanglement wave for the first time

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