Quantum computers might one day break Bitcoin, but the same physics that threatens crypto could also create something better: unforgeable money. This week, researchers Stefano Gogioso and Daniela Herrmann argued that quantum money — a concept first sketched in the late 1960s — may be the final form of digital currency, one that doesn't need a blockchain at all.
The physics behind the idea
The core insight is the no-cloning theorem, proved by Wootters and Zurek in 1982. It says an unknown quantum state cannot be perfectly copied. That makes quantum states naturally unique — a property that Stephen Wiesner exploited in the late 1960s when he proposed the first scheme for unforgeable quantum money. His work was published in 1983 and later inspired the BB84 quantum cryptography protocol in 1984.
Unlike today's crypto, which relies on computational hardness (and could be broken by a sufficiently powerful quantum computer), quantum cryptography's security is based on physics. Device-independent cryptography even works if the hardware is built by an attacker. Gogioso's team has built single-use quantum keys that are destroyed when spent, preventing replay attacks.
Gogioso argues that blockchain consensus is 'the last middleman' because it still requires trust in a network and a ledger. Quantum money, by contrast, is self-verifying. A banknote — or a quantum token — can be checked without consulting a central database or a distributed ledger. That could cut out the energy, latency, and governance headaches of proof-of-work or proof-of-stake systems.
In 2012, Scott Aaronson and Paul Christiano proposed the first public-key quantum money scheme, where anyone can verify a token but only the bank can mint it. That line of research is now getting fresh attention as quantum computing advances.
The trust problem
Gogioso's point about trust cuts to the heart of the crypto ethos. Bitcoin was supposed to eliminate middlemen, but it replaced them with a consensus mechanism that requires most of the network to be honest. Quantum money, if it works at scale, would remove that last layer of trust entirely. The question is whether the physics can be turned into a practical payment system — and whether the crypto world is ready to abandon the blockchain it has built.
