Measuring a quantum system without problems

The process of measuring quantum observables has been plagued, since the inception of quantum mechanics, by the so-called measurement problem: it is impossible to read a definite outcome on a quantum scale.

In its mathematical formulation, the problem takes the form of a no-go theorem, preventing the realization of quantum mechanical measurement schemes that comply both with the measurement and unitarity axioms.

Building upon the idea of measurement that dates back to the early days of quantum mechanics, we overcome this century-old problem by proving the existence of a measurement scheme in which the probe (a quantized field) undergoes a quantifiable semiclassical transition, thus allowing, within error limits, for both an objective readout of the measuring device and the compliance with measurement axioms.