Supporting idea questions ask about details directly stated in the passage. You can identify them because they will refer to only one part of the passage (and usually give line numbers). This is a common RC question-type on the GMAT!
One of the first places you should look for official GMAT information is in the Official Guide made by GMAC. On p. 360 it provides a brief intro on Supporting Ideas questions. The takeaway: these questions ask for the main point of a small portion of the passage!
Learning #7 on this Learnboard is a great example of how a relatively easy question can be disguised with unfamiliar vocabulary and harder scientific topics. Don’t let words and phrases like “quantum computers” and “electron charges” throw you — just go back to the passage!