A brief introduction to quantum computing

Let’s start with some principles:

1. Any 2 level system can be used for quantum computing, like spin.

2. Due to dephase and decoherence, we need a clean background（closed box, out of touch with the outside universe), or topological protection.

3. A practical system should be able to be manipulated（the entanglement of qubit) and can be scaled up

Now let’s take a look at a simple example, IBM q