Interesting information about complex physical, biological and environmental systems is
communicated to the external world by weak and low-frequency magnetic signals reflecting
the evolution of the weak magnetization carried by these systems. Similarly, in certain
quantum mechanical ensembles such as spin polarized ultra-cold neutrons or atoms, the
interesting physical information is superimposed on top of their weak magnetization, which
must be strictly controlled in order to observe the desired signal. There exist well established …