A heuristic approach to the assessment of the root mean square quantum noise

The concept of Quantum Noise is intriguing, both from a fundamental and an applied point of view. The interest for this specific subject has recently increased more and more, thanks to the development of sophisticated technologies for the practical realization of real (not only gedanken) quantum experiments, and in view of possible applications in quantum cryptography. In the present paper, we suggest a heuristic approach, an alternative to the existing ones, to assess a priori the so-called Root Mean Square Quantum Noise, quantifying the incidence of measuring apparatuses in introducing noise in quantum measurements.