BTQ and QPerfect design the first quantum circuit for one-shot signatures

[Daz3]

Imagine a digital signature that physically cannot be used twice. Quantum Computing Report says BTQ Technologies and its French subsidiary QPerfect have published a preprint describing the first explicit, circuit level design for quantum one shot signatures

In a one shot signature, the signing key is stored as a fragile quantum state. Signing a message measures and collapses that state, and the no cloning theorem stops anyone copying it first, so the key can only ever sign once. That removes the need for a blockchain or ledger to prevent the same key being reused

Earlier theory relied on complicated mathematical building blocks. The new design replaces them with a single puncturable pseudorandom function built on a tree lookup, plus a reversible routine for sampling the required quantum states. Verification runs entirely on ordinary classical computers

The resources are substantial. A single bit signature needs between 206 and 2,438 logical qubits depending on the security level, and the design was checked using QPerfect's MIMIQ emulator. The keys must also stay coherent until they are used, which points towards long lived hardware such as neutral atoms

Suggested uses include secure delegation, tokenised transfers and trustless random beacons, although these remain possibilities rather than deployments. Fully securing key generation also depends on future advances in quantum obfuscation. Still, turning a theoretical idea into an actual circuit is an important step

Could quantum signatures ever replace blockchains for some uses? And how long until machines have enough logical qubits to run this?

BTQ Technologies and QPerfect Deliver First Circuit-Level Implementation of Quantum One-Shot Signatures - Quantum Computing Reportquantumcomputingreport.com