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ABS | on: FAQ on Microsoft's topological qubit thing
money quote:

  "if Microsoft’s claim stands, then topological qubits have finally reached some sort of parity with where more traditional qubits were 20-30 years ago. I.e., the non-topological approaches like superconducting, trapped-ion, and neutral-atom have an absolutely massive head start: there, Google, IBM, Quantinuum, QuEra, and other companies now routinely do experiments with dozens or even hundreds of entangled qubits, and thousands of two-qubit gates. Topological qubits can win if, and only if, they turn out to be so much more reliable that they leapfrog the earlier approaches—sort of like the transistor did to the vacuum tube and electromechanical relay. Whether that will happen is still an open question, to put it extremely mildly."
tromp | parent | next
The quote that struck me was

> I foresee exciting times ahead, provided we still have a functioning civilization in which to enjoy them.

gauge_field | root | parent | next
If you are shocked by this, I suggest not reading his other recent topics.
moshun | root | parent | next
Spent an hour going through his blog. Wild and unpleasant ride.
HappyPanacea | root | parent | next
I found his blog to be candid and well thought out usually
tdb7893 | root | parent | next
It's interesting to see someone who seems to describe themself as anti-woke try desperately to convince the generally anti-academic movement to fund academics. Sadly I don't think he'll succeed in this.

I don't agree with many of his posts but I think the blog is interesting in how personal it feels. Often I feel like all media is very cultivated but he seems very willing to put his own anxieties and foibles on the web.

KerrAvon | root | parent
FWIW, it's unclear how the NSF ends up. Musk needs scientists to make rockets go. The defense industry needs a broad spectrum of scientists to make all kinds of things happen. Scientists (and especially the schools producing said scientists) need funding to operate, or there will no longer be accredited scientists.

Does Musk understand this? Maybe not. It's not evident so far. He certainly lives in a fictional world of the right wing's devising. Will someone else be able to penetrate that bubble to make him understand it? Will he care if they do? Guess we'll find out.

stogot | root | parent
Why do all schools need public money? The big ones have huge endowments, why not use those? They also make a ton of money from students. Much of it is wasted on layers of administrators, but the administrators will just fire the scientists for not bringing in grants
darknavi | root | parent
The comments section of that blog is truly a wild ride.
fc417fc802 | root | parent
As it should be.

> For most of my professional life, this blog has been my forum, where anyone in the world could show up to raise any issue they wanted, as if we were tunic-wearing philosophers in the Athenian agora.

https://scottaaronson.blog/?p=6576

echelon | root | parent
> If you are shocked by this, I suggest not reading his other recent topics.

Given that this is Scott Aaronson, does he suggest we'll break cryptography and destroy the foundations of the modern internet?

vonneumannstan | root | parent
AI takeover is what he's referencing.
ameliaquining | root | parent
Also distress at various political developments.
| root | parent
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fauigerzigerk | parent | next
There seems to be a bit of a disconnect between the first and the second sentence (to my completely uneducated mind).

If topological qubits turn out to be so much more reliable then it doesn't really matter how much time was spent trying to make other types of qubits more reliable. It's not really a head start, is it?

Or are there other problems besides preventing unwanted decoherence that might take that much time to solve?

tsimionescu | root | parent
The point I think is this: if topological qubits are similar to other types of qubits, then investing in them is going to be disappointing because the other approaches have so much more work put into them.

So, he is saying that this approach will only pay off if topological qubits are a fundamentally better approach than the others being tried. If they turn out to be, say, merely twice as good as trapped ion qubits, they'll still only get to the achievements of current trapped ion designs with another, say, 10-15 years of continued investment.

adastra22 | root | parent
The whole point though is that they are step function better than traditional qubits, in a way that is simply a type error to compare.

The utility of traditional qubits depends entirely on how reliable and long-lived they are, and how to can scale to larger numbers of qubits. These topological qubits are effectively 100% reliable, infinite duration, and scale like semiconductors. According to the marketing literature, at least…

radioactivist | root | parent | next
There are caveats there too. Generally topological qubits can be immune to all kinds of noise (i.e. built-in error correction) but Majorana zero modes aren't exact the right kind of topological for that to be true. They only enjoy protection on most operations, but not all. So there is a still a need for error correction here (and all the complication that entails) it is just hopefully less onerous since only essentially one operation requires it.
pclmulqdq | root | parent
All the other qubits scaled the same way when they were in a simulator, too. When they actually hit reality, they all had huge problems.
adastra22 | root | parent
Other qubits in general do not scale the same way. Some for example do not allow arbitrary point-to-point interactions, which means doubling your physical qubits doesn’t double your number of logical qubits. There are other ways in which scaling was sometimes nonlinear.

Note also that this isn’t a simulated result. Microsoft has an 8-qubit chip they are making available on Azure.

pclmulqdq | root | parent
I am well aware of how other qubits scale, but I am also aware that the physicists who created them didn't expect decoherence to scale this rapidly at the time they took that approach.

IBM sells you 400 qubits with huge coherence problems. When IBM had an 8-qubit chip, they were also pretty stable.

nprateem | parent
Yeah I mean that's exactly what MS are talking about, only requiring 1/20 of the checksum qubits or something.

https://www.ft.com/content/a60f44f5-81ca-4e66-8193-64c956b09...

ABS | root | parent
what Microsoft claim in their marketing copy reported by the FT - for the average reader - and what a third-party, well-known expert in the field thinks... are on very different levels AFAIC

Microsoft is saying: we did it!

Everyone else is saying: prove it!

nprateem | root | parent
Yes, that's why we read decent journalism that includes the opinions of experts. MS are still saying production use is pretty far off.
ABS | root | parent
except we don't need opinions, we need proof and that is what we are lacking.

The only expert in the FT article is Dr. Sankar Das Sarma who (from Wikipedia)

  "In collaboration with Chetan Nayak and Michael Freedman of Microsoft Research, Das Sarma introduced the ν = 5 / 2 topological qubit in 2005"
So you might understand why this FT article is not adding anything to the discussion, which does not discuss the theory but rather MS's claim of an actual breakthrough.

They show a chip, we'd like proof of what the chip actually does