Perhaps you should try some spelling variations:
"quantum mechanical system" » "quantum mechanics system", "quantum mechanical systems"
"quantum dynamical system" » "quantum dynamics system", "quantum chemical system", "quantum dynamical systems", "quantum dynamic systems"

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (("quantum dynamical system") OR ("quantum mechanical system")).
• Removing quotes may allow a broader search: (( quantum dynamical system ) or ( quantum mechanical system )).
• Adding a wildcard symbol may retrieve word variants: (("quantum dynamical system") or ("quantum mechanical system"))*.