[HN Gopher] AlphaQubit: AI to identify errors in Quantum Computers
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AlphaQubit: AI to identify errors in Quantum Computers
Author : roboboffin
Score : 77 points
Date : 2024-11-20 18:37 UTC (4 hours ago)
(HTM) web link (blog.google)
(TXT) w3m dump (blog.google)
| dogma1138 wrote:
| How can a classical system detect/correct errors in a quantum
| one? I thought all the error correction algos for quantum also
| relied on qbits e.g. Shor Code.
| anon291 wrote:
| It's not a perfect detector. If you give up perfection and
| settle for X% accuracy, then you can use a classical system
| (FWIU).
| summerlight wrote:
| Quantum computing is not intractable and can be still simulated
| with a sufficient amount of time. This work used quantum
| simulator to generate data points then use it to train a
| transformer, which doesn't seem that different from other
| neural network use cases to optimize computation heavy
| problems.
|
| The question would be whether this approach still works when it
| is scaled to thousands or even millions of qubits. The team is
| optimistic that that is the case, but we will see.
| drdeca wrote:
| The model could choose which measurement operations to make on
| the qubits, and which operations to take to repair the qubits?
|
| In some quantum error correcting codes, there is a large set of
| operators that, when there are currently no errors, measuring
| these will not change the state (well, assuming the measurement
| is made without error), but would result in some information
| about the kind of error if there is an error, and this info can
| be used to choose what operations to take to correct the error.
|
| For a number of such schemes, there's a choice of a strategy of
| what schedule to check which of the measurements with, and how
| to correct the errors.
| fizx wrote:
| The error correction itself requires qbits, but reading out the
| final answer apparently becomes more probabilistic and complex,
| to the point where a neural net is a reasonable solution for
| interpretation and denoising.
| Strilanc wrote:
| The full error correction system involves qubits. This paper is
| mainly about the decoder, which is responsible for taking the
| symptom data produced by the quantum circuit and determining
| the most likely errors that caused those symptoms. In the blog
| post it's not stated what code is being run, but in the
| illustration it's clear it's a surface code [1] and this is
| confirmed in the paper's abstract [2].
|
| Disclaimer: am one of the authors, but not a main contributor.
| I wrote the simulator they used and made some useful
| suggestions on how to use it to extract information they wanted
| for training the models more efficiently, but know nothing of
| transformers.
|
| [1]: https://errorcorrectionzoo.org/list/quantum_surface
|
| [2]: https://www.nature.com/articles/s41586-024-08148-8.pdf
| abdullahkhalids wrote:
| The world of quantum has all these interesting gotchas.
|
| In a quantum computer, your logical quantum state is encoded in
| lots of physical qubits (called data qubits) in some special
| way. The errors that occur on these qubits are indeed
| arbitrary, and for enough physical qubits are indeed not
| practically classically simulatable.
|
| To tackle these errors, we do "syndrome measurement" i.e.
| interact the data qubits with another set of physical qubits
| (called syndrome qubits), in a special way, and then measure
| the syndrome qubits. The quantum magic that happens is that the
| arbitrary errors get projected down to a countable and finite
| set of classical errors on the data and syndrome qubits!!!
| Without this magic result we would have no hope for quantum
| computers.
|
| Anyway, this is where a decoder - a classical algorithm running
| on a classical computer - comes in. OP is a decoder. It takes
| the syndrome qubit measurements and tries to figure out what
| classical errors occurred and what sort of correction, if any,
| is needed on the data qubits.
| sigmar wrote:
| >AlphaQubit, a recurrent-transformer-based neural-network
| architecture that learns to predict errors in the logical
| observable based on the syndrome inputs (Methods and Fig. 2a).
| This network, after two-stage training--pretraining with
| simulated samples and finetuning with a limited quantity of
| experimental samples (Fig. 2b)--decodes the Sycamore surface code
| experiments more accurately than any previous decoder (machine
| learning or otherwise)
|
| >One error-correction round in the surface code. The X and Z
| stabilizer information updates the decoder's internal state,
| encoded by a vector for each stabilizer. The internal state is
| then modified by multiple layers of a syndrome transformer neural
| network containing attention and convolutions.
|
| I can't seem to find a detailed description of the architecture
| beyond this bit in the paper and the figure it references. Gone
| are the days when Google handed out ML methodologies like
| candy... (note: not criticizing them for being protective of
| their IP, just pointing out how much things have changed since
| 2017)
| jncfhnb wrote:
| Eh. It was always sort of muddy. We never actually had an
| implementation of doc2vec as described in the paper.
| myownpetard wrote:
| That's because attention is all we need.
| s1dev wrote:
| When maintaining a quantum memory, you measure parity checks of
| the quantum error correcting code. These parity checks don't
| contain any information about the logical state, just (partial)
| information about the error, so the logical quantum information
| remains coherent through the process (i.e. the logical part of
| the state is not collapsed).
|
| These measurements are classical data, and a computation is
| required in order to infer the most likely error that led to the
| measured syndrome. This process is known as decoding.
|
| This work is a model that acts as a decoding algorithm for a very
| common quantum code -- the surface code. The surface code is
| somewhat like the quantum analog of a repetition code in a sense.
| abdullahkhalids wrote:
| I would instead give the example of the Hamming code. As you
| probably know, you can construct a quantum code, the Steane
| code, which is just analogous to Hamming code.
|
| The Steane code is the simplest triangular color code. i.e. you
| can arrange all the qubits on a 2D triangular lattice, and only
| do nearest neighbor interactions [1]. The surface code is a
| similar quantum code, in which the qubits can also be placed on
| a 2D lattice, except that lattice is made up of squares.
|
| Why do we care about 2D surfaces and nearest neighbor
| interactions. Because it makes building quantum hardware
| easier.
|
| EDIT:
|
| [1] The Steane code's picture is shown here.
| https://errorcorrectionzoo.org/c/steane Seven data qubits are
| on the vertices of the triangles. 2 syndrome qubits on each of
| the faces.
| zb3 wrote:
| We're almost there, now we just need to incorporate crypto here
| somehow :)
| m3kw9 wrote:
| Been trying for the longest time, I still don't understand how
| quantum computing work. It's always something-something tries all
| possible combinations and viola, your answer.
| benchmarkist wrote:
| Every quantum algorithm is a unitary operation in a Hilbert
| space. If you want to understand the theory then you will have
| to do the actual work of learning about Hilbert spaces and
| unitary operators.
| dekhn wrote:
| """Are Git branches, in fact, "homeomorphic endofunctors
| mapping submanifolds of a Hilbert space"?"""
| Chabsff wrote:
| The whole "tries all possible combinations" thing is a very
| misleading oversimplification in the first place.
|
| Instead, think of it more like a _completely_ different set of
| operations than classical computers that, if you were to try
| and replicate /simulate them using a classical computer, you
| would have no choice but to try all possible combinations in
| order to do so. Even that is oversimplifying, but I find it at
| least doesn't hint at "like computers, but faster", and is as
| close as making the parallelism pov "correct" as you're going
| to get.
|
| What these operations do is pretty exotic and doesn't really
| map onto any straightforward classical computing primitives,
| which puts a pretty harsh limit of what you can ask them to do.
| If you are clever enough, you can mix and match them in order
| to do _some_ useful stuff really quickly, much faster than you
| ever could with classical computers. But that only goes for the
| stuff you can make them do in the first place.
|
| That's pretty much the extent I believe someone can
| "understand" quantum computing without delving into the actual
| math of it.
| krackers wrote:
| >It's always something-something tries all possible
| combinations
|
| "If you take nothing else from this blog: quantum computers
| won't solve hard problems instantly by just trying all
| solutions in parallel." - Scott Aaronson
|
| This short comic he helped author actually summarizes the core
| idea fairly well https://www.smbc-comics.com/comic/the-talk-3
| elpocko wrote:
| >viola
|
| A large violin provides little answers.
| DarmokJalad1701 wrote:
| https://www.youtube.com/watch?v=F_Riqjdh2oM
|
| This video is the simplest explanation that I have found for
| Quantum Computing which doesn't do the whole pop-sciency "is
| both zero and one at the same time" nonsense.
| outworlder wrote:
| So, an inherently error-prone computation is being corrected by
| another very error prone computation?
| leptons wrote:
| I've never seen so much money spent on a fundamentally flawed
| tech, since maybe Theranos. I'm really starting to doubt the
| viability of the current crop of quantum computing attempts. I
| think there probably is some way to harness quantum effects,
| but I'm not sure computing with inherently high margin of error
| is the right way to do it.
| sctb wrote:
| No problem, said von Neumann.
| https://www.scottaaronson.com/qclec/27.pdf
| latentsea wrote:
| I feel like this is basically how humanity operates as a whole,
| and that seems to produce usable results, so why the heck not?
| xen2xen1 wrote:
| This all feels like the "with a computer" patents of yore.
| moomoo11 wrote:
| Interesting. I don't know too much about quantum computers tbh.
|
| Quantum computer parts list:
|
| - Everything you need
|
| - A bunch of GPUs
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