eigenket (u/eigenket)

eigenket commented on What Bikini Atoll Looks Like Today (2017) medium.com/stanford-magaz... · Posted by u/voxadam

prerok · 5 months ago

Sorry, say what? C-14 comes from exposure to radiation also from the sun. Dating by it would make no sense in recent history because it would be too hard. Am I missing something?

eigenket · 5 months ago

This graph [1] available on Wikipedia answers this question. The level of carbon 14 in the atmosphere (in the southern hemisphere) roughly doubled between 1955 and 1963 ish. This coincides with the era of above ground nuclear testing. Since then it has been decaying back to the baseline.

[1] https://en.wikipedia.org/wiki/Carbon-14#/media/File%3ARadioc...

eigenket commented on FAQ on Microsoft's topological qubit thing scottaaronson.blog/?p=866... · Posted by u/ingve

jokoon · 6 months ago

I wonder if this means that ai will have more capabilities with quantum computing.

So far, I haven't read how those chips are programmed, but it seems like it requires to re learn almost everything.

I don't even know if there is an OS for those.

eigenket · 6 months ago

There is not an "OS" or anything even remotely like it. For now these things behave more like physics experiments than computers.

You can play around with "quantum programming" through (e.g.) some of IBM's offerings and there has been work on quantum programming languages like q# from Microsoft but its unclear (to me) how useful these are.

eigenket commented on FAQ on Microsoft's topological qubit thing scottaaronson.blog/?p=866... · Posted by u/ingve

blablabla123 · 6 months ago

Quite confusing though

> “There’s no slam dunk to know immediately from the experiment” that the qubits are made of topological states, says Simon. (A claim of having created Majorana states made by a Microsoft-funded team based in Delft, The Netherlands, was retracted in 2021.) The ultimate proof will come if the devices perform as expected once they are scaled up, he adds.

https://www.nature.com/articles/d41586-025-00527-z

eigenket · 6 months ago

I'm not sure what that has to do with my previous comment but yeah, pushing the boundaries of science is kinda difficult and you can make mistakes.

My understanding is that they pretty convincingly showed that the thing they built acts as a qubit. This means that if its not doing what they think its doing (the "topological" / Majorana stuff) then they accidentally made a qubit which works some other way. That isn't outside the realm of possibility but it is fairly unlikely.

eigenket commented on FAQ on Microsoft's topological qubit thing scottaaronson.blog/?p=866... · Posted by u/ingve

blablabla123 · 6 months ago

The chip is literally called Microsoft Majorana 1

Indeed Majorana fermions are completely unseen/unconsidered outside of Neutrinos. In fact all Standard Model fermions except Neutrinos are proven to be Dirac fermions

eigenket · 6 months ago

The Majorana particles in Microsoft's set-up are "quasi-particles". They aren't really fundamental particles, but excitations in the system which behave (roughly, in some appropriate sense) like particles. They aren't neutrinos.

eigenket commented on Prime numbers so memorable that people hunt for them scientificamerican.com/ar... · Posted by u/georgecmu

bhasi · 7 months ago

But it's not prime - what am I missing? Why is this anecdote significant?

eigenket · 7 months ago

The point is that Grothendieck, easily one of the greatest mathematicians of all time, who regularly proved deep and fundamental facts about prime numbers, cared so little about particular numbers that he accidentally gave an easy to see non-prime as an example of a prime.

He was used to working on completely different levels of abstraction, so when faced with concrete numbers he could easily make a mistake that a school-child (or hacker news commenter) could spot.

eigenket commented on Willow, Our Quantum Chip blog.google/technology/re... · Posted by u/robflaherty

perching_aix · 8 months ago

They explicitly cover all of these caveats in the announcement.

Problems that benefit from quantum computing as far as I'm aware have their own formal language class, so it's also not like you have to consider Sabine's or any other person's thoughts and feelings on the subject - it is formally demonstrated that such problems exist.

Whether the real world applications arrive or not, you can speculate for yourself. You really don't need to borrow the equally unsubstantiated opinion of someone else.

eigenket · 8 months ago

The formal class is called BQP, in analogy with the classical complexity clas BPP. BQP contains BPP but there is no proof that it is stictly bigger (such a proof would imply P != NP). There are problems in BQP we expect are not in BPP but its not clear if there are any useful problems in BQP and not in BPP, other than essentially Shor's algorithm.

On the other hand it's actually not completely necessary to have a superpolynomial quantum advantage in order to have some quantum advantage. A quantum computer running in quadratic time is still (probably) more useful than a classical computer running in O(n^100) time, even though they're both technically polynomial. An example of this is classical algorithms for simulating quantum circuits with bounded error whose runtime is like n^(1/eps) where eps is the error. If you pick eps=0.01 you've got a technically polynomial runtime classical algorithm but it's runtime is gonna be n^100, which is likely very large.

eigenket commented on A rudimentary quantum network link between Dutch cities tudelft.nl/en/2024/tu-del... · Posted by u/FrankyHollywood

dwnw · 10 months ago

Lots of handwaving there. Particularly with "and I can (locally) do stuff"

Good luck with all of that.

eigenket · 10 months ago

The I can locally do stuff is completely understood theoretically/mathematically. I hand waved because this isn't a forum where those technicalities are particuarly relevant.

Its been well understood since at least 1993

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.71...

eigenket commented on A rudimentary quantum network link between Dutch cities tudelft.nl/en/2024/tu-del... · Posted by u/FrankyHollywood

dwnw · 10 months ago

Amplification would absorb one photon and replace it with one or more new photons. Definitely not quantum.

Personally, I always wonder why point-to-point connections are called "networks". The information is not quantum at any node, even if there are multiple nodes in a system.

Then there's "quantum internet", which makes no sense at all. What are we going to do, run direct fiber from every computer to every other computer directly? You can't hop safely or anything. Don't get me started on the total bullshit that is the "quantum repeater", now we need "quantum switch" too?

We call serial port connections things like "link", "connection", etc. We typically don't call them networks until we start linking them all together with simple routing logic that doesn't inherently require access to all the unencrypted information the packets contain and such.

To me these are all just signs that the whole scheme is/was and will forever be mostly crankery.

Quantum networking is an oxymoron. It doesn't allow end-to-end encryption and in exchange gives back extremely fragile single link security properties.

eigenket · 10 months ago

I don't think it's completely clear (to me) that quantum networking is an oxymoron. I would enthusiastically agree that its very complicated and the real world use cases are incredibly limited.

As far as your routing/switching qualms go I think they are mostly addressed by entanglement swapping? Person A and person B can each make an entangled pair and send me half, and I can (locally) do stuff which leads to the halves they keep at home becoming entangled. Then they can use teleportation or whatever to do whatever they want between themselves without me knowing anything about it.

eigenket commented on Yes, we did discover the Higgs theoryandpractice.org/202... · Posted by u/EvgeniyZh

Galatians4_16 · 10 months ago

Gödel's incompleteness Theorem, applied to QM, in three paragraphs.

eigenket · 10 months ago

Neither of Gödel's two incompleteness theorems apply to quantum mechanics.

The two theorems apply to logical systems which prove facts about the natural numbers. While this is an incredibly broad class of things, it doesn't include physical theories like quantum mechanics.

eigenket commented on Big advance on simple-sounding math problem was a century in the making quantamagazine.org/big-ad... · Posted by u/isaacfrond

l33t7332273 · 10 months ago

Less than 100 years later, we stand waiting for nuclear bombs guided by GPS to be launched when the authorization cryptographic certificate is verified.

eigenket · 10 months ago

Nuclear weapons (based on quantum mechanics and special relativity) were used less than 6 years after that quote.