So this is me. A decade ago, I would have been a plausible choice of referee for a paper like this.

https://scholar.google.com/citations?user=C6BzRwwAAAAJ

You'll have to take my word for it, as I don't currently have a university job. For some reason, Google doesn't let you authenticate your Scholar account with your ORCID account, even though they trust ORCID to verify that you wrote the papers.

This paper sounds legitimate to me. If it was made up, it would be a fraud, not a spoof. That's unlikely, because the authors come from the most legitimate institutions there are (The University of Oxford, The National University of Singapore). ArXiv verifies institutional affiliation. Even if it is made up, the experiment is plausible.

I can get how it sounds like a spoof. I laughed out loud at:

> We simulate the electric fields and capacitance shifts using ANSYS Maxwell where the tardigrade is modelled as a cube of length 100μm

I.e, they literally assume a cubical tardigrade in a vacuum!

Actually, I did present this experiment as a spoof, at a physics department O-week camp 20 years ago. I think we used a monkey instead of a tardigrade. It was as lame as it sounds.

> My favorite laugh line from the paper: "Maximum likelihood estimation was then employed to prevent the resulting density matrix from having nonphysical properties."

What they did is totally legitimate. Reconstructing density matrices is numerically unstable, a bit like any computerized tomography. This is similar to constraining a noisy CAT scan, to avoid the "nonphysical property" that the air at some point in your lungs has density less than zero.

Engtangling a live animal is a hell of a party trick. No doubt about that. So how much does this matter scientifically? Here we're getting into subjective territory, and what follows is my opinion.

The surprising aspect is biological, not physical. I might have guessed that, if you cooled a tardigrade to the temperature that quantum electronics operate at, you could use it as a quantum electronic component. I wouldn't have guessed that the tardigrade would get up and walk away afterwards!

The philosophical significance? It depends, of course. For materialists like me, who make sense of quantum wierdness the Everettian way, it makes no difference. Of course electrons can get entangled, and the electrons in a tardigrade—or a physicist—are still electrons. (The price we pay is a very, very, odd sense of personal identity.)

For idealists, this is quite a big deal. If you insist that you are a definite state of consciousness, then you need to draw a line somewhere, between the part of the universe that is you, and the other parts that can be quantum superpositions. Twenty years ago, that was easy: you're an animal, not an atom, duh.

This makes it a bit harder: you're a ... big animal? How big, exactly? You could be some non-electronic degree of freedom, but surely that's a stretch neurologically.

It's a lot easier to draw a categorical distinction of animal vs mineral than of human-like observers vs other animals. If they can entangle a tardigrade, then in principle they could entangle your pet dog. Is it much comfort that they can't, yet, entangle you?