system
Given the following post, respond as if you're commenting on Reddit:
human
[Harry Potter] Why didn’t Quirrell just use a summoning charm to get the Philosopher’s Stone, or the Imperius Curse to force Harry to hand it over? For that matter, why didn’t he just stun/kill Harry and take it by force?

I’m referring to when Quirrell realized it was in Harry’s pocket, not before.
gpt
We know that summoning charms don't work on Horcruxes. Perhaps the same is true for the stone. 

Quirrel isn't really a dark wizard. He is just carrying one around. It's possible that he doesn't know how to perform the imperious curse, especially not one that is strong enough to compel Harry to do something like that. 

Voldemort doesn't want Harry did. He wants to kill him himself and eventually use him for resurrection.