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Comment by strangeloops85

2 days ago

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."

https://static-content.springer.com/esm/art%3A10.1038%2Fs415...

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strangeloops85

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torsten_karzig  1 day ago

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.

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.

  • gsf_emergency_2  1 day ago

    >signal-to-noise ratio of 1

    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%.

throw_pm23  2 days ago

Another recent writeup that adds some nuance to this (and other claims), summarizing the quantum-skeptic positions:

https://gilkalai.wordpress.com/2025/02/17/robert-alicki-mich...

  • ameliaquining  2 days ago

    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.

    • throw_pm23  1 day ago

      I think he is playing it smart. The more fringe/contrarian it is, the bigger the payoff if he turns out to be right. So far nothing of much use came out of QC, and if nothing will, then the hype pendulum swings back at some point, and he will win big. If not, his position will seem silly, but not much risk to his reputation, being skeptic of a new model is intellectually fine and even courageous if it goes against the mainstream. I see it as those who called out "replication crisis" in social sciences.

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