3 ms·

Well, I'm envious that you didn't have to deal with those people. I am involved on the theory side of the implementation of different kinds of solid state qubi

by tagrun 7y ago

Well, I'm envious that you didn't have to deal with those people. I am involved on the theory side of the implementation of different kinds of solid state qubits, so you may say I'm biased, but the question really isn't whether we will ever get it or not, the question is when. We already have had exponential growth in single qubit coherence times in the past decade, we have very good entangling gates, and there isn't any fundamental reason why the number of qubits can't be increased. It's not like there is an invisible great barrier ahead of us, and nothing in the physics of these devices say we can't. By the way, they aren't using quantum error correction methods right now, basically because it's not worth it: you need a lot of physical qubits to encode a high quality logical qubits.

mlyle 7y ago
Right-- so if we need 10-1000 qubits per high-quality error corrected boolean-ish qubit and 20,000 error-corrected qubits to really tackle interesting real world problems, we need 3-5 orders of magnitude improvement. The fact that we have exponential improvements to parts of the process is nice. But exponential improvement doesn't continue forever. Extrapolating from the current status 5 orders of magnitude out seems reckless.
- tagrun 7y ago
  I don't know what exactly your belief is rooted on (clearly not physics), but of course you're free to put your money wherever you want, just be aware that: - Qubits are not boolean. Classical error correction does not work in quantum computers. You need quantum error correction. - The exponential improvements are in single qubit coherence times, and a stagnation in those improvements doesn't prevent an increase in the number of qubits. (it'd be nice to have, though, because then eventually we wouldn't even need error correction) - No, it doesn't take 1000 or even 100 physical qubits to have a high fidelity qubit (it can actually be 1:1 with dynamical error correction) or 20000 error corrected qubits to tackle real world problems (Shor's algorithm isn't the only interesting thing out there, simulating some quantum systems requires far less qubits and probably more interesting for people in natural sciences) - Even if we were 3-5 orders of magnitudes away in # of qubits, it's still a matter of time, and there is still nothing fundamental in physics or material science that prevents having millions of physical qubits. - Now I feel like I'm dealing with one of those non-physicists people again who claim quantum computers are a pipe dream, only this time instead of a faulty physical argument, it has no real technical basis at all, so this is where I'd like to stop. Enjoy the rest of your day
  - mlyle 7y ago
    > - Qubits are not boolean. Classical error correction does not work in quantum computers. You need quantum error correction. Yah, no shit sherlock. I'm sorry you didn't like my handwavy sentence and a half phrasing of my post, but your tone is just not necessary. > - No, it doesn't take 1000 or even 100 physical qubits to have a high fidelity qubit (it can actually be 1:1 with dynamical error correction) or 20000 error corrected qubits to tackle real world problems (Shor's algorithm isn't the only interesting thing out there, simulating some quantum systems requires far less qubits and probably more interesting for people in natural sciences) Shor's algorithm is a really important milestone. Lots of interesting problems are harder than factoring. We think we need ~2000 logical qubits to get to the most basic interesting cases of Shor's, and with some multiple for error correction we have 3 OOM right there. > Even if we were 3-5 orders of magnitudes away in # of qubits, it's still a matter of time, and there is still nothing fundamental in physics or material science that prevents having millions of physical qubits. There probably isn't. But there may be in economics or systems complexity. > - Now I feel like I'm dealing with one of those non-physicists people again who claim quantum computers are a pipe dream, only this time instead of a faulty physical argument, it has no real technical basis at all, so this is where I'd like to stop. Enjoy the rest of your day Yah, assuming that we can extrapolate maintain the current rate of progress for an 5 OOM improvement is reasonable. Just one question: how many orders of magnitude of improvement will we gain at the current rate? Can we get 5? 20? 100? Obviously we start running into things like the mass of the planet, but perhaps there's some limiting factors before then? :P It's really hard to pin down where they are ahead of time. If we double qubits and coherence annually, 5 OOM is 40+ years. How many years will this doubling continue at an annual pace? How long until we're all just enslaved to make qubits? ;)

by tagrun 7y ago

mlyle 7y ago

Right-- so if we need 10-1000 qubits per high-quality error corrected boolean-ish qubit and 20,000 error-corrected qubits to really tackle interesting real world problems, we need 3-5 orders of magnitude improvement. The fact that we have exponential improvements to parts of the process is nice. But exponential improvement doesn't continue forever. Extrapolating from the current status 5 orders of magnitude out seems reckless.

tagrun 7y ago
I don't know what exactly your belief is rooted on (clearly not physics), but of course you're free to put your money wherever you want, just be aware that: - Qubits are not boolean. Classical error correction does not work in quantum computers. You need quantum error correction. - The exponential improvements are in single qubit coherence times, and a stagnation in those improvements doesn't prevent an increase in the number of qubits. (it'd be nice to have, though, because then eventually we wouldn't even need error correction) - No, it doesn't take 1000 or even 100 physical qubits to have a high fidelity qubit (it can actually be 1:1 with dynamical error correction) or 20000 error corrected qubits to tackle real world problems (Shor's algorithm isn't the only interesting thing out there, simulating some quantum systems requires far less qubits and probably more interesting for people in natural sciences) - Even if we were 3-5 orders of magnitudes away in # of qubits, it's still a matter of time, and there is still nothing fundamental in physics or material science that prevents having millions of physical qubits. - Now I feel like I'm dealing with one of those non-physicists people again who claim quantum computers are a pipe dream, only this time instead of a faulty physical argument, it has no real technical basis at all, so this is where I'd like to stop. Enjoy the rest of your day
- mlyle 7y ago
  > - Qubits are not boolean. Classical error correction does not work in quantum computers. You need quantum error correction. Yah, no shit sherlock. I'm sorry you didn't like my handwavy sentence and a half phrasing of my post, but your tone is just not necessary. > - No, it doesn't take 1000 or even 100 physical qubits to have a high fidelity qubit (it can actually be 1:1 with dynamical error correction) or 20000 error corrected qubits to tackle real world problems (Shor's algorithm isn't the only interesting thing out there, simulating some quantum systems requires far less qubits and probably more interesting for people in natural sciences) Shor's algorithm is a really important milestone. Lots of interesting problems are harder than factoring. We think we need ~2000 logical qubits to get to the most basic interesting cases of Shor's, and with some multiple for error correction we have 3 OOM right there. > Even if we were 3-5 orders of magnitudes away in # of qubits, it's still a matter of time, and there is still nothing fundamental in physics or material science that prevents having millions of physical qubits. There probably isn't. But there may be in economics or systems complexity. > - Now I feel like I'm dealing with one of those non-physicists people again who claim quantum computers are a pipe dream, only this time instead of a faulty physical argument, it has no real technical basis at all, so this is where I'd like to stop. Enjoy the rest of your day Yah, assuming that we can extrapolate maintain the current rate of progress for an 5 OOM improvement is reasonable. Just one question: how many orders of magnitude of improvement will we gain at the current rate? Can we get 5? 20? 100? Obviously we start running into things like the mass of the planet, but perhaps there's some limiting factors before then? :P It's really hard to pin down where they are ahead of time. If we double qubits and coherence annually, 5 OOM is 40+ years. How many years will this doubling continue at an annual pace? How long until we're all just enslaved to make qubits? ;)