A key factor for the performance of sensors is the speed at which the system returns to its initial state after a disturbance or measurement, similar to the taring of a balance. In the quantum sensor under investigation, this corresponds to the transition of electrons from an energetically excited s tate to the ground state. However, the electrons remain in a kind of metastable intermediate state for a short time. A team of physicists from Julius-Maximilians-Universität Würzburg (JMU) has now directly measured this waiting time in a two-dimensional material: It lasts exactly 24 billionths of a second. ...read more read less