Many-body effects in quantum metrology

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We study the impact of many-body effects on the fundamental precision limits in quantum metrology.

• On the one hand such effects may lead to non-linear Hamiltonians, studied in the field of non-linear quantum metrology, while on the other hand they may result in decoherence processes that cannot be described using single-body noise models.
• We provide a general reasoning that allows to predict the fundamental scaling of precision in such models as a function of the number of atoms present in the system.
• Moreover, we describe a computationally efficient approach that allows for a simple derivation of quantitative bounds.