The real world application fields convert these theories into smaller easier to understand rules that you can hold, touch, taste, and smell. A microchip groups a ton of sub micro scale components working together as a factory to produce a device that is used to make another device , etc. Each one of those sub scale components was meticulously designed to work in a certain way using well understood rules. We likely do not have the understanding of lower level quantum-ish magic that makes it work, but we do know how to build real things with our simpler rules.