A quantum simulator uses an array of qubits to represent another quantum system directly. Molecules, chemical reactions, and other physical phenomena can be mapped onto the qubits and studied as a quantum system in their own right, rather than being approximated as a set of equations solved on a classical computer.
This idea traces back to Richard Feynman, who observed that simulating quantum systems on classical machines becomes impossibly expensive as the systems grow, and that a computer built from quantum parts would be far better suited to the task. Simulating the behaviour of electrons in a material or the bonds in a molecule is a natural fit for a quantum processor.
Quantum simulation is one of the most promising near-term applications of quantum computing, with potential impact across drug discovery, materials science, and clean energy. It can be pursued on today’s devices in limited form, while its most valuable applications await the larger, more reliable processors that scalable platforms such as silicon spin qubits are designed to deliver.