All the abstract nonsense you need to program a quantum computer

Chris Ferrie
2 min readAug 24, 2020

Welcome to Introduction to Quantum Computing. I am your guide, Associate Professor Chris Ferrie, a researcher in the UTS Centre for Quantum Software and Information. These are the notes for Lab 3. You should have already enjoyed Lecture 3. The syllabus is here:

In Lecture 3, you were introduced to multiple qubit states and entanglement. This required the new tool of the tensor product. Today we will work through exercises to ensure you are a proficient user of these tools — that is, let’s make you a quantum mechanic!

Reminder! All the abstract nonsense you need to program a quantum computer

By now you should be familiar with some of these. By the time you are finished the exercises in this Lab, they should be committed to memory. These represent the foundation of quantum computing.

Likewise, you should know the basic properties of linear operators — matrices in the usual representation — as most intuitively follow the rules of arithmetic. The key thing they don’t satisfy is commutativity. That is AB ≠ BA.

The tensor product was new, so you may need to refer back to this. The most important thing to remember is that things that are on the left of the tensor product stay on the left! — and similarly for all other positions in chains of tensor products. Also, remember that the tensor product symbol is often suppressed. If it is not clear, you are probably missing some assumed context.

The Quiz!

The quiz is hosted externally, but should embed here fine. If not, navigate to: https://csferrie.typeform.com/to/lyA1yxVX.

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Chris Ferrie

Quantum theorist by day, father by night. Occasionally moonlighting as a author. csferrie.com