Sekoia

@Sekoia@lemmy.blahaj.zone

• ⁨Comment⁩ on ⁨Test of a prototype quantum internet runs under New York City for half a month⁩ ⁨⁨3⁩ ⁨months⁩ ago⁩:

  Ah, my bad then.

• ⁨Comment⁩ on ⁨Test of a prototype quantum internet runs under New York City for half a month⁩ ⁨⁨3⁩ ⁨months⁩ ago⁩:

  … what you said is correct, but that’s superposition, not entanglement. Entanglement is when you create a product state of several qubits that cannot be decomposed into a tensor product of basic states (a single proton/photon/whatever).

• ⁨Comment⁩ on ⁨Test of a prototype quantum internet runs under New York City for half a month⁩ ⁨⁨3⁩ ⁨months⁩ ago⁩:

  Oh yeah, that. My bad, mixed 'em up.

  The original algorithm doesn’t use entanglement, though! Just the fact that measurements can change the state. You can pick an axis to measure a quantum state in. If you pick two axes that are diagonal to each other, measuring a state in the “wrong” axis can give a random result (the first time), whereas the “right” one always gives the original data.

  So the trick is to have the sender encode their bits into a randomly-picked axis per bit (the quantum states), send the states over, and then the receiver decodes them along a random axis as well. On average, half the axes will match up and those bits will correspond. The other bits are junk (random). They then tell each other the random axes they picked, which identifies the right bits!

  They can compare a certain amount of their “correct” bits: if there’s an eavesdropper, they must have measured in the wrong state half the time (on average). Measurement changes the state into its own axis, so the receiver gets a random bit instead of the right one half the time. 25% of the time, the bits mismatch, when they should always correspond.

• ⁨Comment⁩ on ⁨Test of a prototype quantum internet runs under New York City for half a month⁩ ⁨⁨3⁩ ⁨months⁩ ago⁩:

  You can have post-quantum cryptography using classical computation, though

  (“Simply” pick a problem with no quantum acceleration. I think Elliptic Curves Cryptography works, but I’m not an expert)

• ⁨Comment⁩ on ⁨The next Cortana: Copilot on Windows is no reason to buy a new PC⁩ ⁨⁨8⁩ ⁨months⁩ ago⁩:

  You’re totally right. I started reading the article, got distracted, and thought I’d already read it. I agree with you then.

  I still don’t trust Microsoft to not phone all your inputs home though.

• ⁨Comment⁩ on ⁨The next Cortana: Copilot on Windows is no reason to buy a new PC⁩ ⁨⁨8⁩ ⁨months⁩ ago⁩:

  I don’t think Windows’ Copilot is locally processed? Could very well be wrong but I thought it was GPT-4 which is absurd to run locally.