ABSTRACT
This chapter considers continuous measurements of harmonic oscillators. As has been mentioned, in many situations real systems may actually be treated as harmonic oscillators. Many real systems may be treated approximately as harmonic oscillators or systems of harmonic oscillators. For example, measurement of an oscillator is often performed in a narrow frequency interval near the resonance frequency. The chapter investigates a measurement of this type for a harmonic oscillator as the measured system. Measurement of the coordinate frequency component allows one to estimate the frequency component of the force acting on the oscillator during the measurement. The system of connected harmonic oscillators is a universal model for any oscillating system in a state close to its equilibrium state. All of two or more connected oscillators may display quantum properties. Therefore the problem of measurements in a system of connected quantum oscillators naturally arises.
