Quick aside: The difference between quantum randomness, which is absolute, and classical randomness, which basically means “very hard to predict”, is covered a bit in this older post. This is called “fundamental”, “irreducible”, or “quantum” randomness. Generally speaking, any individual quantum event will be drowned out by the noise of all of the other quantum events around it, and the average is the only important thing. For example, the meter on a Geiger counter is an example of quantum randomness on a large-scale. A quantum random number generator is essentially the same as an ordinary random number generator.