"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."
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?
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.
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
A very important statement is in the peer review file that everyone should read:
"The editorial team wishes to point out that the results in this manuscript do not represent evidence for the presence of Majorana zero modes in the reported devices. The work is published for introducing a device architecture that might enable fusion experiments using future Majorana zero modes."
Thanks for your interest. I'm part of the Microsoft team. Here are a couple of comments that might be helpful:
1) The Nature paper just released focuses on our technique of qubit readout. We interpret the data in terms of Majorana zero modes, and we also do our best to discuss other possible scenarios. We believe the analysis in the paper and supplemental information significantly constrains alternative explanations but cannot entirely exclude that possibility.
3) On top of the Nature paper, we have recently made addition progress which we just shared with various experts in the field at the Station Q conference in Santa Barbara. We will share more broadly at the upcoming APS March meeting. See also https://www.linkedin.com/posts/roman-lutchyn-bb9a382_interfe... for more context.
That's from the abstract of the upcoming conference talk (Mar14)
>Towards topological quantum computing using InAs-Al hybrid devices
Presenter: Chetan Nayak (Microsoft)
The fusion of non-Abelian anyons is a fundamental operation in measurement-only topological quantum computation. In one-dimensional topological superconductors, fusion amounts to a determination of the shared fermion parity of Majorana zero modes. Here, we introduce a device architecture that is compatible with future tests of fusion rules. We implement a single-shot interferometric measurement of fermion parity in indium arsenide-aluminum heterostructures with a gate-defined superconducting nanowire . The interferometer is formed by tunnel-coupling the proximitized nanowire to quantum dots. The nanowire causes a state-dependent shift of these quantum dots' quantum capacitance of up to 1fF. Our quantum capacitance measurements show flux h/2e-periodic bimodality with a signal-to-noise ratio of 1 in 3.6 microseconds at optimal flux values. From the time traces of the quantum capacitance measurements, we extract a dwell time in the two associated states that is longer than 1ms at in-plane magnetic fields of approximately 2T. These measurements are discussed in terms of both topologically trivial and non-trivial origins. The large capacitance shift and long poisoning time enable a parity measurement with an assignment error probability of 1%.
As the recent results from CS and math on the front pages have shown, one doesn't have to be unknown or underfunded in order to produce
verifiable breakthroughs, but it might help..
Seems like John Baez didn't notice those lines in the peer review either
I think that Kalai here is very seriously understating how fringe/contrarian his views are. He's not merely stating that there's too much optimism about potential future results, or that there's some kind of intractable theoretical or practical bottleneck that we'll soon reach and won't be able to overcome. He's saying that any kind of quantum advantage—a thing that numerous experiments, from different labs in academia and industry, using a wide variety of approaches, have demonstrated over the past decade—is impossible, and therefore all of those experimental results were wrong and need to be retracted. His position was scientifically respectable back when the possibility he was denying hadn't actually happened yet, but I don't think it is anymore.
I think what many people are missing in the discussion here is that topological qbits are essentially a different type of component. This is analogous to relay-triode-transistor technology progression.
It is speculation still whether the top-q approach will be effective, but there are significant implications if it is. Scalability, reliability, and speed are all significant aspects on the table here.
While other technologies have a significant head start, much of the “head start” is transferrable knowledge, similar to the relay-triode-transistor-integrated circuit progression. Each new component type multiplies the effectiveness of the advances made by the previous generation of technologies, it doesn’t start over.
IF the topological qubits can be made to be reliable and they live up to their scalability promises, it COULD be a revolutionary step, enabling exponential gains in cost, scalability, and capability. IF.
topological analytics shows that under like-like exchanges multiple distinct pathways exist in 2D (in 3D topology does not have distinct pathways for these exchanges). this permits real anyon particles to exist when the physics is confined to 2D within quantum limits such as in a layer of graphene. certain configurations of layers (“moire materials”) can be made periodic to provide a suitable scale lattice for anyons to localize and adopt particular quantum states
anyons lie somewhere between fermions and bosons in their state occupancy and statistics - no 2 fermions may occupy the same state, bosons can all occupy the same state, anyons follow rational number patterns eg up to 2 anyons can occupy 3 states
I enjoy the quality of "it's too early to say" in Aaronson's writing. It won't stop share price movement or hopeless optimism amongst others.
I do wonder if he is running a simple 1st order differential on his own beliefs. He certainly has the chops here, and self introspection on the trajectory of highs and lows and the trends would interest me.
A bit off topic - I really like Scott Aaronson and his blog, but hate the comment section - he engages a lot with the comments (which is great!) but it's really hard to follow, as each comment is presented as a new message.
I made this small silly chrome extension to re-structure the comments to a more readable format - if anyone is interested
I find the opposite, he often makes some ridiculous claim in the post, the comments (the ones he lets through) rightfully point out how wrong he was, then he cherry-picks and engages one of the more outrageous comments, so a superficial observer is left with the impression that the original claim was OK.
Readit News
> I foresee exciting times ahead, provided we still have a functioning civilization in which to enjoy them.
Deleted Comment
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?
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.
https://www.ft.com/content/a60f44f5-81ca-4e66-8193-64c956b09...
Microsoft is saying: we did it!
Everyone else is saying: prove it!
"The editorial team wishes to point out that the results in this manuscript do not represent evidence for the presence of Majorana zero modes in the reported devices. The work is published for introducing a device architecture that might enable fusion experiments using future Majorana zero modes."
https://static-content.springer.com/esm/art%3A10.1038%2Fs415...
1) The Nature paper just released focuses on our technique of qubit readout. We interpret the data in terms of Majorana zero modes, and we also do our best to discuss other possible scenarios. We believe the analysis in the paper and supplemental information significantly constrains alternative explanations but cannot entirely exclude that possibility.
2) We have previously demonstrated strong evidence of Majorana zero modes in our devices, see https://journals.aps.org/prb/pdf/10.1103/PhysRevB.107.245423.
3) On top of the Nature paper, we have recently made addition progress which we just shared with various experts in the field at the Station Q conference in Santa Barbara. We will share more broadly at the upcoming APS March meeting. See also https://www.linkedin.com/posts/roman-lutchyn-bb9a382_interfe... for more context.
Hmmm.. appreciate the honesty :)
That's from the abstract of the upcoming conference talk (Mar14)
>Towards topological quantum computing using InAs-Al hybrid devices
Presenter: Chetan Nayak (Microsoft)
The fusion of non-Abelian anyons is a fundamental operation in measurement-only topological quantum computation. In one-dimensional topological superconductors, fusion amounts to a determination of the shared fermion parity of Majorana zero modes. Here, we introduce a device architecture that is compatible with future tests of fusion rules. We implement a single-shot interferometric measurement of fermion parity in indium arsenide-aluminum heterostructures with a gate-defined superconducting nanowire . The interferometer is formed by tunnel-coupling the proximitized nanowire to quantum dots. The nanowire causes a state-dependent shift of these quantum dots' quantum capacitance of up to 1fF. Our quantum capacitance measurements show flux h/2e-periodic bimodality with a signal-to-noise ratio of 1 in 3.6 microseconds at optimal flux values. From the time traces of the quantum capacitance measurements, we extract a dwell time in the two associated states that is longer than 1ms at in-plane magnetic fields of approximately 2T. These measurements are discussed in terms of both topologically trivial and non-trivial origins. The large capacitance shift and long poisoning time enable a parity measurement with an assignment error probability of 1%.
Seems like John Baez didn't notice those lines in the peer review either
https://mathstodon.xyz/@johncarlosbaez/114031919391285877
TIL: read the peer review first
https://gilkalai.wordpress.com/2025/02/17/robert-alicki-mich...
It is speculation still whether the top-q approach will be effective, but there are significant implications if it is. Scalability, reliability, and speed are all significant aspects on the table here.
While other technologies have a significant head start, much of the “head start” is transferrable knowledge, similar to the relay-triode-transistor-integrated circuit progression. Each new component type multiplies the effectiveness of the advances made by the previous generation of technologies, it doesn’t start over.
IF the topological qubits can be made to be reliable and they live up to their scalability promises, it COULD be a revolutionary step, enabling exponential gains in cost, scalability, and capability. IF.
Microsoft unveils Majorana 1 quantum processor - https://news.ycombinator.com/item?id=43104071 - Feb 2025 (150 comments)
anyons lie somewhere between fermions and bosons in their state occupancy and statistics - no 2 fermions may occupy the same state, bosons can all occupy the same state, anyons follow rational number patterns eg up to 2 anyons can occupy 3 states
Deleted Comment
I do wonder if he is running a simple 1st order differential on his own beliefs. He certainly has the chops here, and self introspection on the trajectory of highs and lows and the trends would interest me.
I made this small silly chrome extension to re-structure the comments to a more readable format - if anyone is interested
https://github.com/eliovi/shtetl-comment-optimized
Deleted Comment