Runtimes for problems in P are O(n) = constant, O(n^2), O(n^10000), and any O(n^k) = polynomial time.
Just a slight nitpick: Constant run time is O(1), not O(n).
When we reach quantum computing we will be on the level of DNA. Look at it like this, a base 3 code would be like our TVs which use three colors to display a flat picture of thousands of different color variations. that could take the form of -, 0, or +. So you could have your switch go one way for - another way for 0 (no voltage) or another way for + voltage. Now that's something we already have all around us, it's called AC power. Go one more level and you would have a base 4 code like our DNA which makes us in 3D not just a flat screen.