To understand a complex quantum system, scientists build another quantum system that behaves in the same way. It is like building a small bridge across a river to understand how a large bridge will behave. But how do you know the small bridge won't deceive you? The answer: simulation is not just a demonstration but a bridge between model and reality, and it needs to be stress-tested.
Trust in a simulator is not an objective property but the result of a verification process: tests, comparisons, and gradual accumulation of confidence. Just as a bridge is trusted after thousands of trucks have driven over it, a simulator is trusted after its predictions have matched reality in thousands of cases. In the future, when simulators begin to surpass classical computers, verifying their reliability will become the main task.
The term 'quantum simulator' is often attributed to Richard Feynman, who in 1982 suggested that quantum systems are best modeled by quantum devices. However, the very idea of using one physical system to study another dates back to ancient mechanical models of celestial bodies.