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singularity2001last Wednesday at 6:34 PM6 repliesview on HN

  given a million qubits ...
also last time I checked the record was 80 qubits and with every doubling of the cubits the complexity of the system and the impurities and the noise are increasing. so it's even questionable whether there will ever be useful quantum computers

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ABSlast Wednesday at 7:15 PM

Microsoft Research entire point is that their approach will allow

  "fault-tolerant quantum computing architecture based on noise-resilient, topologically protected Majorana-based qubits."
Roadmap to fault tolerant quantum computation using topological qubit arrays https://arxiv.org/abs/2502.12252
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euclid211last Thursday at 4:49 AM

The issue isn't really impurities and noise, quantum error-correction solves that problem. The issue is that the supporting technologies don't scale well. Superconducting qubit computers like google's have a bunch of fancy wires coming out of the top, basically one for each qubit. You can't have a million wires that size, or even a smaller size, so the RF circuitry that sends signals down those wires needs to be miniaturized and designed to operate at near 0K so it can live inside the dilution refrigerator, which is not easy.

Microsoft's technology is pretty far behind as far as capacity but the scaling limitations are less significant and the error-correction overhead is either eliminated or smaller.

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pankajdohareylast Wednesday at 7:21 PM

Based on what i read it seems a lot of algorithmic work is required to even make them useful. New algorithms have to be discovered and still they will only solve only a special class of problems. They cant do classical computing so your NVIDIA GPU probably may never be replaced by a Quantum GPU.

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moffkalastlast Wednesday at 7:40 PM

Hopefully not, besides quantum physics simulations the only problems they solve are the ones that should remain unsolved if we're to trust the integrity of existing systems.

As soon as the first practical quantum computer is made available, so much recorded TLS encrypted data is gonna get turned into plain text, probably destroying millions of people's lives. I hope everyone working in quantum research is aware of what their work is leading towards, they're not much better than arms manufacturers working on the next nuke.

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Agentuslast Wednesday at 6:47 PM

i vaguely remember reading an article about solving the correlation between quantum decoherence and scaling of qubit numbers. i dont understand quantum computers so take it with a grain of salt.

but here’s what perplexity says: “Exponential Error Reduction: Willow demonstrates a scalable quantum error correction method, achieving an exponential reduction in error rates as the number of qubits increases125. This is crucial because qubits are prone to errors due to their sensitivity to environmental factors25. ”

ernesthlast Wednesday at 9:05 PM

> last time I checked the record was 80 qubits

It has progressed since: IBM Condor (demonstrated in december 2023) has 1121 qubits.

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