Quantum computing’s most feared milestone just got a firm date attached to it. IonQ CEO Niccolo de Masi is predicting that Q-Day, the moment when a quantum computer becomes powerful enough to break widely used encryption standards, will arrive in 2028.
The cryptographic standard underpinning Bitcoin’s transaction security, secp256k1 elliptic-curve signatures, is on the list of protocols that a sufficiently powerful quantum machine could compromise.
What IonQ’s numbers actually say
IonQ published a resource estimate in September 2026 putting the qubit requirement for breaking 256-bit elliptic-curve signatures at roughly 19,400 to 20,000 physical qubits. Running Shor’s algorithm against a secp256k1 signature at that scale would take approximately 26 days of continuous computation.
De Masi’s own hardware roadmap is calibrated to that timeline. IonQ is targeting delivery of its 256-qubit Superion systems by 2027, with an ambition to reach 10,000 physical qubits by 2028.
