A universal quantum computer is a general-purpose machine. Rather than being built for one narrow task, it can in principle execute any quantum algorithm. This universality comes from the idea of a universal gate set: any quantum computation can be assembled from a small collection of basic quantum gates, provided the set includes single-qubit operations together with at least one entangling two-qubit gate.
This contrasts with more specialised machines such as quantum simulators or annealers, which are designed for particular classes of problem. A universal, gate-based quantum computer can be programmed to run anything from Shor’s factoring algorithm to quantum chemistry simulations, in the same way a classical CPU can run any program.
Building a universal quantum computer that is also useful requires far more than a complete gate set. It requires those gates to be applied with very high fidelity across millions of qubits, which in turn depends on fault-tolerant quantum computing. Quantum Motion is building a full-stack, universal machine on silicon spin qubits, using CMOS manufacturing to reach the scale that a general-purpose quantum computer demands.