Perhaps you should try some spelling variations:
"quantum physical" » "quantum physics", "quantum critical", "quantum logical"
"quantum chemical" » "quantum mechanical", "quantum chemistry"
"quantum optical" » "quantum optics"

Try widening your search to All Fields.

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 physical") OR ("quantum optical"))) OR ((("quantum classical") OR ("quantum chemical")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"quantum physical\") or (\"quantum optical\"))) or (((\"quantum classical\") OR (\"quantum chemical\"))))".
• Removing quotes may allow a broader search: (((( quantum physical ) or ( quantum optical ))) or ((( quantum classical ) OR ( quantum chemical )))).
• Adding a wildcard symbol may retrieve word variants: (((("quantum physical") or ("quantum optical"))) or ((("quantum classical") OR ("quantum chemical"))))*.