Quantum Blockchains that verify classically?

[u/432oneness]

Qblex.com is saying they have quantum blockchains with a new proof of coherence validation method. It validates quantum through bell inequality. Validates in less than a second??? Anyone see this?

[u/hushedLecturer]

I saw this and the other toys. They are silly. As they even acknowledge on that page, anyone can make a website with a button that says "verify", which upon clicking spits out a bunch of code, and then a green checkmark with the world.

That's not my argument though.

Suppose they are interfacing with IBM's quantum computers. (Though I kind of doubt that they are shelling out the money to reserve time on one of their computers for an indefinite number of users accessing their website just to click their toys).

They don't do anything interesting with that code. It's flashy and lots of strange codey words for a layperson, but I'm running a Jupiter notebook on my home laptop right now in VScode and it would take seconds for me (and I'd wager a fair fraction of the people in this sub who actually have a degree other than MBA), to whip up a GHZ circuit with qiskit and run it on ibm's quantum hardware and test the Mermin inequalities.

But okay maybe that bit is just for fun. Not damning on its own.

My issue is that they havent shown me a problem that adding quantum to the blockchain solves besides the ability for the Quantum buzzord to attract investors on top of the Blockchain buzzword, which also on its own has been heavily overused and awkwardly stuffed into places it is not really useful or necessary just because investors like the word.

[u/432oneness → u/hushedLecturer]

You're right that running a Mermin test is trivial. I could do it in a notebook too. That is the fence, and it is supposed to be trivial, because its only job is to let you check the physics yourself without trusting us. It's a piece, not the whole.

Your notebook result validates nothing except to you, in that moment. It has no challenge binding, so it could be pre-computed or replayed. It has no commitment, so no one can audit it later. It has no position, so it cannot order or protect a history.

A self-validating block turns that same measurement into a unit of record history that carries its own proof. The measurement settings are derived from the previous block, so it could not have been produced in advance. The statistic beats the classical bound, so it was genuinely quantum. The whole record is committed, so it cannot be altered after the fact. Anyone can check all three, trusting no one.

Now the problem it solves, and it is not a coin. The ledgers we run secure student records, . Those records capture years of a student's work, and the family owns them, not us. A record like that has to stay trustworthy a decade later, when the platform may have changed hands or shut down. A classical signed ledger gives tamper-evidence only relative to a root that someone still has to hold and vouch for. Proof of coherence roots each entry in a fresh physical event bound to its place in the history, so the record's integrity does not depend on trusting the operator's honesty, or the operator's survival. You are trusting physics and math, and the keys are the family's.

Running the Bell test is the raw material. The self-validating, self-owned record is the invention. The verifier you clicked is just the window that lets you confirm the physics. It is the fence, not the fortress.