Appears in collection : 2018 - T2 - WS1 - Observability and estimation in quantum dynamics

A general model of unitary parameter estimation in presence of Markovian noise is considered, where the parameter to be estimated is associated with the Hamiltonian part of the dynamics. In absence of noise, unitary parameter can be estimated with precision scaling as 1/T, where T is the total probing time. A simple algebraic condition involving solely the operators appearing in the quantum Master equation, decides whether 1/T or 1/\sqrt{T} scaling of precision is achievable using the most general adaptive quantum estimation strategies.