A new way of measuring atomic-scale magnetic fields with great precision, not only up and down but sideways as well, has been developed by researchers at MIT. The new tool could be useful in applications as diverse as mapping the electrical impulses inside a firing neuron, characterizing new magnetic materials, and probing exotic quantum physical phenomena.
Source: https://phys.org/news/2019-03-quantum-method-minuscule-magnetic-fields.html