twitch
(this is very wrong)
https://news.ycombinator.com/item?id=27439839
"What makes quantum computing so hard to explain?"
A qubit is a complex unit vector, wherein the classical states of 0 and 1 correspond to antipodal points on the unit sphere painted by the range of possible qubits.
I'd imagine the following Google image [1] is sufficiently understandable to a child: the two dots are bits while the sphere is a qubit.
[1] - http://langsrv.astro.cf.ac.uk/research/research_SQDFWM/Bloch...
Quantum computers store data as states that are either 0 or 1 when you measure them, but before measurement they are in a superposition of these two. Quantum computers are initialized in a ground state, and are programmed by slowly modifying the system such that the new ground state is the solution to the problem you care about. Then you do the measurements and the state collapses to the solution you want.
There are certain specific problems where evolving and collapsing the system in this way is demonstrably faster than the best classical computer algorithms we have today.
With this analogy you get some feeling for what manipulating the ground state means, and why you need to do so slowly, and also that this is not a tool that will solve all types of problems.