4 ms·

Where does this sit on the "applicably breaking secure classical cryptography" spectrum?

krastanov 5y ago
Many years away. A good guestimate is that you need 1M physical qubits factor numbers fast. Also, there is classical public-key cryptography (i.e. encryption algorithms that run efficiently on today's classical computers) that is not susceptible to quantum computers. And symmetric cryptography has never been susceptible to quantum computers.
- saalweachter 5y ago
  So if we draw an exponential curve from 53 to 127 qubits, we're looking at 13 doublings or about 2 decades? Neat!
cgearhart 5y ago
It’s completely irrelevant to that problem. Breaking crypto requires quantum error correction, which we think requires thousands (perhaps hundreds of thousands) of physical qubits per logical qubit. And the operations of the computation require many more logical qubits than just representing the target value. It’s still gonna be awhile. But this is still pretty interesting because a lot of the detractors of quantum computing thought there was strong evidence that we’d never even manage to get this far. So it seems _slightly_ more likely that large scale abstract quantum computation is feasible.
StLCylone 5y ago
There are probably entities saving encrypted data right now for when that day arrives. Brings up many interesting lines of thought beyond "is it breakable right now?"
- krastanov 5y ago
  Does it really though? Every secure system design pretty much assumes that the cryptographic standard will be broken in a few decades. Is there really any secret today that would be problematic if made public 30 years in the future? And that would not have been made public by some other method anyway?
  - Maursault 5y ago
    > Is there really any secret today that would be problematic if made public 30 years in the future? Sure. For one, that all the major earthquakes in the last 30 years, resulting tsunamis, destruction and loss of life, were manmade and intentionally caused by, say, Nabisco. Also, it would be a little shocking to the public if it were revealed there are no humans left, only alien-hybrids.
    - samus 5y ago
      Both of these facts would be quite irrelevant when ultimately discovered. It is hard to make people care about anything that happened 30 years ago that did not affect them personally, and in the latter case the alien-hybrids would have to just... accept the fact.
bnjemian 5y ago
Gidney and Ekerå have you covered: https://arxiv.org/abs/1905.09749 https://arxiv.org/abs/1905.09749 Short answer, this probably won't even register as a pitstop on the technical pathway.

Many years away. A good guestimate is that you need 1M physical qubits factor numbers fast. Also, there is classical public-key cryptography (i.e. encryption algorithms that run efficiently on today's classical computers) that is not susceptible to quantum computers. And symmetric cryptography has never been susceptible to quantum computers.

saalweachter 5y ago
So if we draw an exponential curve from 53 to 127 qubits, we're looking at 13 doublings or about 2 decades? Neat!

cgearhart 5y ago

It’s completely irrelevant to that problem. Breaking crypto requires quantum error correction, which we think requires thousands (perhaps hundreds of thousands) of physical qubits per logical qubit. And the operations of the computation require many more logical qubits than just representing the target value. It’s still gonna be awhile. But this is still pretty interesting because a lot of the detractors of quantum computing thought there was strong evidence that we’d never even manage to get this far. So it seems _slightly_ more likely that large scale abstract quantum computation is feasible.

StLCylone 5y ago

There are probably entities saving encrypted data right now for when that day arrives. Brings up many interesting lines of thought beyond "is it breakable right now?"

krastanov 5y ago
Does it really though? Every secure system design pretty much assumes that the cryptographic standard will be broken in a few decades. Is there really any secret today that would be problematic if made public 30 years in the future? And that would not have been made public by some other method anyway?
- Maursault 5y ago
  > Is there really any secret today that would be problematic if made public 30 years in the future? Sure. For one, that all the major earthquakes in the last 30 years, resulting tsunamis, destruction and loss of life, were manmade and intentionally caused by, say, Nabisco. Also, it would be a little shocking to the public if it were revealed there are no humans left, only alien-hybrids.
  - samus 5y ago
    Both of these facts would be quite irrelevant when ultimately discovered. It is hard to make people care about anything that happened 30 years ago that did not affect them personally, and in the latter case the alien-hybrids would have to just... accept the fact.

bnjemian 5y ago

Gidney and Ekerå have you covered: https://arxiv.org/abs/1905.09749 https://arxiv.org/abs/1905.09749 Short answer, this probably won't even register as a pitstop on the technical pathway.