The quantum realm is another dimension (as seen by Doctor Strange on his flying acid trip in Nepal) and therefore accessible by sling ring. The only question is, does the reality stone permanently transmute objects into bubbles, or do they return to their original form when the wielder leaves or relaxes his finger as happened to Drax and Mantis? If it's the latter this wouldn't work. And I'm thinking it may indeed be the latter, as Quill is seen in these two scenes on Titan with BOTH his quad blasters, despite one being turned to bubbles earlier on Knowhere. Nuts.
This is Thorin, one of my ferrets. Here he is sitting on my cartooning desk like he owns the place. Am I not the king?!