In a quantum simulation, the evolution of a quantum many-body system is 'emulated' by mapping the Hamiltonian onto the one of a real system or by encoding in qubits [for a review see Buluta and Nori, Science 326, 108 (2009)]. This will be particularly important if the exponentially growing computational complexity does not allow for a simulation on a classical computer.
This will be easier to implement than systems for quantum computation, since smaller systems and lower accuracies would suffice, and decoherence could in some cases even be taken advantage of for the simulation of open systems.
There is still something that classical computational physicists and their computers could learn from the field of quantum computing/simulation: the development of classical algorithms for simulation based on ideas from quantum information science (see e.g. Chap. 5 in R. Orus' PhD thesis [link]).
Thoughts after the March for Science
12 hours ago