I am new to quantum mechanics and this is probably a dumb question. What experiments can we do to produce a quantum harmonic oscillator? For example, for a classical harmonic oscillator, we can attach a ball to a spring, make it vibrate, and observe how its position change as time goes on. For quantum harmonic oscillator, how do we set up such an experiment, and what can we measure in the experiment? 

**EDIT**: I searched around and found another post asking about one-dimensional infinite-well model. But I didn't found one for harmonic oscillator. [References on experimental realization of quantum one-dimensional infinite-well model](https://physics.stackexchange.com/q/135725/)