While I'm still eager to see where Quantum Computing leads, I've got a new threshold for "breakthrough": Until a quantum computer can factor products of primes larger than a few bits, I'll consider it a work in progress at best.

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Strilanc 8 months ago | parent | next [-]

If qubit count increased by 2x per year, largest-number-factored would show no progress for ~8 years. Then the largest number factored would double in size each year, with RSA2048 broken after a total of ~15 years. The initial lull is because the cost of error correction is so front loaded.

Depending on your interests, the initial insensitivity of largest-number-factored as a metric is either great (it reduces distractions) or terrible (it fails to accurately report progress). For example, if the actual improvement rate were 10x per year instead of 2x per year, it'd be 3 years until you realized RSA2048 was going to break after 2 more years instead of 12 more years.

	▲	xscott 8 months ago \| parent [-]
		What's the rough bit count of the largest numbers anyone's quantum computer can factor today? Breaking RSA2048 would be a huge breakthrough, but I'm wondering if they can even factor `221 = 13*17` yet (RSA8). And as I've mentioned elsewhere, the other QC problems I've seen sure seem like simulating a noisy circuit with a noisy circuit. But I know I don't know enough to say that with confidence.

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UberFly 8 months ago | parent | prev | next [-]

I guess like most of these kinds of projects, it'll be smaller, less flashy breakthroughs or milestones along the way.

	▲	Terr_ 8 months ago \| parent [-]
		People dramatically underestimate how important incremental unsung progress is, perhaps because it just doesn't make for a nice memorable story compared to Suddenly Great Person Has Amazing Idea Nobody Had Before.

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mrandish 8 months ago | parent | prev | next [-]

> While I'm still eager to see where Quantum Computing leads

Agreed. Although I'm no expert in this domain, I've been watching it a long time as a hopeful fan. Recently I've been increasing my (currently small) estimated probability that quantum computing may not ever (or at least not in my lifetime), become a commercially viable replacement for SOTA classical computing to solve valuable real-world problems.

I wish I knew enough to have a detailed argument but I don't. It's more of a concern triggered by reading media reports that seem to just assume "sure it's hard, but there's no doubt we'll get there eventually."

While I agree quantum algorithms can solve valuable real-world problems in theory, it's pretty clear there are still a lot of unknown unknowns in getting all the way to "commercially viable replacement solving valuable real-world problems." It seems at least possible we may still discover some fundamental limit(s) preventing us from engineering a solution that's reliable enough and cost-effective enough to reach commercial viability at scale. I'd actually be interested in hearing counter-arguments that we now know enough to be reasonably confident it's mostly just "really hard engineering" left to solve.

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ashleyn 8 months ago | parent | prev | next [-]

My first question any time I see another quantum computing breakthrough: is my cryptography still safe? Answer seems like yes for now.

	▲	catqubit 8 months ago \| parent \| next [-]
		Depends on your personal use. In general to the ‘Is crypto still safe’ question, the answer is typically no - not because we have a quantum computer waiting in the wings ready to break RSA right now, but because of a) the longevity of the data we might need to secure and b) the transition time to migrate to new crypto schemes While the NIST post quantum crypto standards have been announced, there is still a long way to go for them to be reliably implemented across enterprises. Shor’s algorithm isn’t really going to be a real time decryption algorithm, it’s more of a ‘harvest now, decrypt later’ approach.
	▲	xscott 8 months ago \| parent \| prev [-]
		I have a pseudo-theory that the universe will never allow quantum physics to provide an answer to a problem where you didn't already know the result from some deterministic means. This will be some bizarre consequence of information theory colliding with the measurement problem. :-)

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kridsdale1 8 months ago | parent | prev | next [-]

There will be a thousand breakthroughs before that point.

	▲	xscott 8 months ago \| parent [-]
		That just means that the word "breakthrough" has lost it's meaning. I would suggest the word "advancement", but I know this is a losing battle.

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dekhn 8 months ago | parent | prev [-]

quantum computers can (should be able to; do not currently) solve many useful problems without ever being able to factor primes.

	▲	xscott 8 months ago \| parent \| next [-]
		What are some good examples? The one a few years ago where Google declared "quantum supremacy" sounded a lot like simulating a noisy circuit by implementing a noisy circuit. And that seems a lot like simulating the falling particles and their collisions in an hour glass by using a physical hour glass.
	▲	Eji1700 8 months ago \| parent \| prev [-]
		Yeah I think that's the issue that makes it hard to assess quantum computing. My very layman understanding is that there are certain things it will be several orders of magnitude better at, but "simple" things for a normal machine quantum will be just as bad if not massively worse. It really should be treated as a different tool for right now. Maybe some day in the very far future if it becomes easier to make quantum computers an abstraction layer will be arrived at in some manner that means the end user thinks it's just like a normal computer, but from a "looking at series of 1/0's" or "looking at a series of superimposed particles" it's extremely different in function.