Quantum computers aren't magic. Their computing primitives - qubits - just have some special properties that can be used to make algorithms that are much faster than classical computers for certain problems. A qubit is basically a bit with a certain probability that it will "reduce" to 0 or 1 when read. While this is non-deterministic, it can easily be modelled, with a slowdown.

Here is a talk which may explain it better https://www.youtube.com/watch?v=8bLXHvH9s1A (The stuff about qubits and quantum computers starts at 30 minutes, but you may find the lead-up interesting/informative).