Quantum-mechanical limitations in macroscopic experiments and modern experimental technique

Perfection of the technique of macroscopic physical experiments has recently been proceeding so intensively that we can now inquire naturally under what conditions in macroscopic experiments will an increase in sensitivity be limited by the quantum-mechanical properties of the test objects. In this article we determine the limiting values of the detectable accelerations (or forces) when free particles or oscillators are used as the test objects. The conditions for attaining the limiting sensitivity are discussed. It is shown possible to increase the sensitivity of a converter of mechanical into electrical oscillations by increasing the relaxation time of the electric resonator. The possibility is discussed of nondestructive recording of the $n$-quantum state of an oscillator. It is shown with the example of a concrete experimental design that one can determine the value of $n$ (including $n=0$) in such a way that the probability of transition to the adjacent levels after the measurement will be small.