Quantum Computing Math
Five hours of background, every idea checked in NumPy.
Three sessions covering the mathematics a first quantum computing course takes for granted: complex numbers, kets and bras, tensor products, unitary and Hermitian matrices, eigenvalues, matrix exponentials and the Fourier transform.
You will not be asked to recite formulas, so this course trains the other skill: knowing what each idea does, why quantum computing needs it, and what it looks like in NumPy. Recognize, don't recite — for every formula, know what it does and when it applies, and let the code carry the details.
Two habits make the difference. Before each code cell, write down what you expect it to print; the surprises are where the learning is. And at the end of each part, answer the prompts in a sentence or two before you open the answers at the foot of the page.
The third lesson is the short one, an hour rather than two. It is where phase and gates finally meet, and the demonstration at the end is the smallest thing on the site that could not happen in classical computing.
- Who it's for
- Anyone starting a quantum computing course who wants the background in place first. You need Python, enough NumPy to index an array, and no physics. Written alongside CSCI 5730, whose lectures are shared with CSCI 4140.
Lessons
Qubits and Complex Numbers
What a qubit holds, why its amplitudes have to be complex, and what phase does to a wave.
the Born rulecomplex amplitudesmodulus squaredthe conjugateMulti-Qubit States and Gates
Building a state out of several qubits, why every gate is unitary, and what eigenvalues say about one.
outer productsprojectorstensor productsnp.kronExponentials, Fourier and Interference
Matrix exponentials, the Fourier transform, and the one demonstration that shows phase changing an answer.
Taylor seriesthe matrix exponentialexpminvolutory matrices