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Quantum computers move closer to the assembly line
21–30 of 36 posts
Re: Quantum computers move closer to the assembly line
#22Earlier quoted context omitted.
As I understand from Wikipedia there are four fundamental quantum algorithms that perform better in some way than the best-known classical counterparts, and many more algorithms in total. The four fundamental ones are: * HHL algorithm for solving (sparse & insensitive) systems of linear equations * Grover's search algorithm for determining black-box inputs * Shor's algorithm for factoring primes * Quantum fourier tra…
You should be very skeptical of all those applications except Shor. HHL: Here's a quote from Ewin Tang [1]: "We know that quantum computers can “efficiently solve” high-dimensional linear algebra problems; however, this assumes that we have some way to evolve a quantum system precisely according to input data, a much harder problem than the linear algebra itself." [1] https://ewintang.com/blog/2019/01/28/an-overview-…
> this assumes that we have some way to evolve a quantum system precisely according to input data, a much harder problem than the linear algebra itself
That's a fair point. I guess I was interpreting OP's question as "what can we do once we have engineered quantum computers", and would categorise this "harder problem" as an engineering problem.
Re: Quantum computers move closer to the assembly line
#23I’ve been a huge skeptic of this field for years. If anything, this summary makes me even more skeptical. The new innovations in laser grid isolated qubits sound amazing until you realize that many if not most (or all?) of those qubits aren’t actually functionally addressable in these systems.
Add to that the facts that error correction will clearly require exponentially more qubits than are programmable; power requirements for cooling or lasers are outlandish and unlikely to shrink significantly; and we don’t even have all that many particularly good quantum algorithms.
Worst of all, all the announcements for the past few years have been in the form of press releases talking about “plans” for new developments and “five year horizons”. Every academic article and new university QC lab is co-sponsored by a VC-funded corporation with every incentive to lie and mislead until a good exit point. This is not the behavior of a highly promising field.
Re: Quantum computers move closer to the assembly line
#24Earlier quoted context omitted.
As I understand from Wikipedia there are four fundamental quantum algorithms that perform better in some way than the best-known classical counterparts, and many more algorithms in total. The four fundamental ones are: * HHL algorithm for solving (sparse & insensitive) systems of linear equations * Grover's search algorithm for determining black-box inputs * Shor's algorithm for factoring primes * Quantum fourier tra…
You should be very skeptical of all those applications except Shor. HHL: Here's a quote from Ewin Tang [1]: "We know that quantum computers can “efficiently solve” high-dimensional linear algebra problems; however, this assumes that we have some way to evolve a quantum system precisely according to input data, a much harder problem than the linear algebra itself." [1] https://ewintang.com/blog/2019/01/28/an-overview-…
Also, just to add, 'quantumalgorithmszoo.org' is quite out of date: For example, they claim a polynomial speed-up for network flow, but that's based on the SOTA in 2007. These days, there's an almost-linear time classical algorithm [A], and no matching quantum algorithm (and also the idea that you would want to use a quantum computer to shave a factor n^(0.0001) is ridiculous). Now, all these statements are only about asymptotics, but don't get me started on practicalities: The idea that in the next 50 years you would use a quantum computer for any problem with only a polynomial speed-up is silly.
[A] https://www.quantamagazine.org/researchers-achieve-absurdly-...
Re: Quantum computers move closer to the assembly line
#25I wish there were a big prize for the first quantum computer shown capable of factoring any product of two odd 4-bit primes {3,5,7,11,13} using Shor's algorithm. I do not expect such a prize to be won in the next decade. Or two.
Re: Quantum computers move closer to the assembly line
#26Earlier quoted context omitted.
You should be very skeptical of all those applications except Shor. HHL: Here's a quote from Ewin Tang [1]: "We know that quantum computers can “efficiently solve” high-dimensional linear algebra problems; however, this assumes that we have some way to evolve a quantum system precisely according to input data, a much harder problem than the linear algebra itself." [1] https://ewintang.com/blog/2019/01/28/an-overview-…
> this assumes that we have some way to evolve a quantum system precisely according to input data, a much harder problem than the linear algebra itself That's a fair point. I guess I was interpreting OP's question as "what can we do once we have engineered quantum computers", and would categorise this "harder problem" as an engineering problem.
> would categorise this "harder problem" as an engineering problem.
I'm not sure what your relation to the field is, but I have found that a lot of things that look like engineering problems from the outside, end up being theoretical and fundamental problems from within. This is often the case when I discuss quantum noise of gravitational wave detectors. I often see people say things like "I wouldn't want to be the guy who has to make these gravitational wave detectors less noisy", almost implying it's just a case of one guy sitting there turning some knobs, but in reality it's thousands of physicists coming up with entirely new theoretical frameworks, often discovering fundamental issues of quantum measurement and control theory (quantum non demolition measurements, quantum squeezing, back action evasion, etc.), or coming up with the most sensitive seismometers ever, or developing new mirror coatings, etc.
Everyone thought that Apple's cancelled wireless charger was just an engineering problem, but it turned out that it seems to be physically impossible to achieve what they wanted.
That said, perhaps in this case you are right, but it's not often obvious what is simply a matter of time and what requires whole new paradigms.
Re: Quantum computers move closer to the assembly line
#27Why is an assembly line needed for a type of computer that has never done a useful calculation?
Investors are impatient, and talk of assembly lines and manufacturing signals to them that an actual product is near. I suspect it’s mostly smoke and mirrors to keep the funding flowing for a few more years.
Re: Quantum computers move closer to the assembly line
#28The recent changes in iMessages and Signal for PQC made me think there may be something imminent going on in this realm
The imminent nonsense of fear-mongering and money wasting, mostly. Academic funds spent billions on PQC and academia has been paid to shill nonsense for long enough to convince some of these players to "ah, let's just integrate PQC, whatever". It's nothing more than a waste of money and resources.
Sorry, huh? Who's paying academia to shill? This is conspiracy thinking.
Changing cryptographic algorithms takes a long time - there are a lot of systems with this stuff embedded in them. Taking some modestly low-cost efforts _now_ to be prepared for a potentially "really bad" future event is more like buying insurance than anything else.
Is it a good choice? I dunno; I have no bets on the likelihood of a working crypto-breaking QC emerging in the next 30 years. But it's not really an irrational thing to worry about on a 10-30 year time horizon, and to simultaneously think that some of the computer systems we design and build today will still be running then.
Re: Quantum computers move closer to the assembly line
#29The recent changes in iMessages and Signal for PQC made me think there may be something imminent going on in this realm
PQC is useful because you can capture and hoard data now and decrypt it later when the hardware becomes available.
Re: Quantum computers move closer to the assembly line
#30The recent changes in iMessages and Signal for PQC made me think there may be something imminent going on in this realm
PQC is useful because you can capture and hoard data now and decrypt it later when the hardware becomes available.
I know, but I'm thinking about the timing. Just speculating.