Quantum simulation
= Quantum simulation
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Quantum simulation uses a controllable <quantum system> to reproduce selected properties or dynamics of another <quantum system>. The motivation is that the <Hilbert space> of many interacting particles grows rapidly, making a full classical representation expensive.
In an analog simulation, an engineered <Hamiltonian> approximates the target interactions directly. In a digital simulation, a sequence of <quantum gates> approximates the target <unitary time evolution>. For example, interacting <spins> can model a <XXZ spin chain>, with measured correlations compared to the target theory. A useful result requires identifying what is reproduced, controlling preparation and measurement errors, and estimating the effect of imperfect interactions. Reproducing a few observables can be valuable even when the simulator does not reproduce every microscopic degree of freedom.