An open-system quantum simulator with trapped ions

We present the realization of an experimental toolbox for simulating an open quantum system with up to five qubits by engineering the multi-qubit dynamics through a controlled coupling to an environment. Using a quantum computing architecture with trapped ions, multi-qubit gates are combined with optical pumping to implement coherent operations and dissipative processes. We illustrate this engineering by the dissipative preparation of entangled states, the simulation of coherent many-body spin interactions, and the quantum non-demolition measurement of multi-qubit observables. Our toolbox represents a conceptual step towards the realization of an open quantum system simulator with applications in various fields, including condensed-matter physics and quantum chemistry, possibly in modeling quantum effects in biology, and in quantum computation driven by dissipation.