In the previous posts, we got to know two different perspectives on quantum computing. First, we regarded qubits as probabilistic systems. Second, we applied linear algebra to visualize the qubit state in the Bloch Sphere.
Unfortunately, both points of view are insufficient when we look at qubits when they are most interesting. That is when they are entangled.
We ended up with not less than a huge explosion.
So, why don’t we ask Obi-Wan for his opinion again?
The graphical representations of single qubits are useless because two entangled qubits share a state of superposition. They are no longer independent of each other. Their values correlate. Once you measure one qubit, the state of the other qubit immediately changes.
But each sphere covers only one of the qubits.
When we cope with entangled qubits, we need to look at the overall quantum system. A single qubit is a combination of 0 and 1. So when you measure it, you could find it in one of these two states.
If you have a quantum system consisting of two qubits, you can find it in one of four states: 00, 01, 10, or 11. There are eight states if you have three qubits, and there are 2^𝑛 states if you have 𝑛 qubits.
It’s time for another perspective.