Quantum to classical transition in spin systems

We experimentally explore extensions to quantum mechanics, that have been proposed to resolve the long-standing problem of quantum measurement. Two on-going experiments will be discussed. The first one, which is based on the inverse Faraday effect in ferrimagnetic resonators, will explore an internal inconsistency originated from the collapse postulate. The second experiment, which is done using spins in diamond, addresses the question whether dynamical instabilities are possible in quantum systems having a Hilbert space of finite dimensionality.