Dateline: Guildford, 4th October 2023.The news that IBM has used a quantum computer to solve a problem that that stumps the leading classical methods is another step on the road to what has become known as “quantum advantage”, where a quantum system solves a problem that cannot be solved by any amount of classical computation. For those of us around fintech, the one problem that we really want to solve is breaking public key cryptography so that we can forge digital signatures, get access to bank systems and, of course, steal a lot of Bitcoin.SharePrioritiesThis is important stuff. In the British government’s new technology strategy, quantum computing is one of the “priority” technologies and it is easy to understand why. That point about solving problems beyond the reach of existing computers means that there is something of an arms race underway, with quantum supremacy as the goal. One of the interesting problems that quantum computer can solve is breaking the asymmetric cryptography at the heart of cryptocurrency in order to transfer money out of lost or abandoned wallets.It will take a while to get to the aforementioned quantum supremacy, where quantum computers can outgun the classical incumbents. Detailed calculations by people who what they are talking about suggests that if quantum computers are put up against a classical supercomputers capable of up to a quintillion (10^18) floating-point operations per second, quantum supremacy could be reached with as few as 208 qubits. But… the IBM solution is already at 127 qubits (quantum bits).with kind permission of Helen…Let’s not Panic about Quantum Computers