Quantum Computing

I hate the LinkedIn communication style, where even sending an email is considered a cornerstone achievement and a huge step forward for humanity. But I have to admit, seeing a real quantum computer in action is truly thrilling: doing the math to understand how and why it works is fascinating, but looking at the output of a real machine is pure satisfaction.

Read the instructions carefully prior to use

In the previous post, we saw how to rotate the density operator with respect to the x, y, and z axes, and we derived simple formulas using Pauli algebra. Building on those results, we can now derive an even more elegant and useful formula for performing rotations around an arbitrary axis. Let's see how!

In this post, we explore a topic already discussed in the previous post: the representation of the density operator on the Bloch sphere. We had observed how the Pauli matrices decompose the density operator; today, we look at something truly crucial in quantum computing: how the density operator evolves under a unitary operator and how this induces nothing but a pure rotation, thus representable on the Bloch sphere. Since the density operator represents the quantum state of t