Physicists generate the first snapshots of fermion pairs | Hacker News Reader

Physicists generate the first snapshots of fermion pairs

news.mit.edu

100 pointshhs11 comments

> "To get a decent view of their behavior, Zwierlein and his colleagues study the particles as a very dilute gas of about 1,000 atoms, that they place under ultracold, nanokelvin conditions that slow the atoms to a crawl. The researchers also contain the gas within an optical lattice, or a grid of laser light that the atoms can hop within, and that the researchers can use as a map to pinpoint the atoms’ precise locations."

This is so cool. It's unbelievable what's possible nowadays

I don't understand how is it possible that they can slow the atoms to a crawl and pinpoint their precise location. Isn't that a violation of the uncertainty principle? Sounds like a lot of certainty to me

I am not educated about particle physics or whatnot, but isnt the uncertainty principle momentum and position cannot be both estimated to arbitrary accuracy? so one could estimate only one of them to arbitrary accuracy and then 1000 particles increases the confidence of that position estimate?

Position and momentum are not separate things that you can measure separately and recombine. They're deeply interrelated.

You would improve your counting statistics somewhat with 1000 particles*, but basically you'd just resolve the Gaussian distribution more clearly. The uncertainty of the measurement comes from the width of the Gaussian, and it's not like measuring more points is going to somehow make that distribution skinnier.

*(a hilariously, impossibly small number in quantum world, where photons come in doses of 10^20/second, or electrons come as 10^18/second)

The Heisenberg uncertainty principle indeed says that we can only achieve a position uncertainty of delta x >= hbar / (2 * delta p). However, this is of course a lower limit on the uncertainty of the position, and hbar is extremely tiny. In practise, we have many other classical noise sources that limit us far before we can ever reach a point where we are Heisenberg-limited.

The noise due to the Heisenberg uncertainty principle would only become "visible" when all of the classical noise sources are reduced such that the classical contribution to delta x * delta y is less than hbar / 2. I don't think this experiment reached such levels of precision

Ahh this makes sense. I wasn't entirely sure if that was actually how hbar/2 related to it, so this clarification is helpful, thanks

* delta p

"I can ride my bike with no handlebars..."

Nah, I'm not trying to be a killjoy or anything. This quote just reminded me of that song after so long of not thinking about it.

can anyone find the link to the paper? I want to see the actual images

The paper is linked in a sidebar on the article itself, and a 1-second google of the title plus "PDF" resulted in an arxiv link.

arxiv.org/pdf/2208.05948.pdf

thanks i missed the sidebar somehow

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