Algorithms

This section is separate from the tutorials. The tutorials teach superposition, interference, and entanglement. An algorithm is a procedure that uses those ideas to answer a definite question with fewer steps than the obvious classical method.

Read them in order. Each page gets harder than the one before it, and each page itself moves from the simplest case to a harder one.

How every algorithm page is organized

The problem: the question, stated so a classical program could answer it too.
The principle: the one quantum idea that makes the procedure work.
From the simple case to the harder one: one bit, then several; one query, then why the cost grows.
A worked example: fqkit code and the output the simulator prints.
Problems: for you to solve. The answers are not on the page.
Where it is used: what the algorithm is actually for, including the limits.

The path

	Algorithm	The question it answers
1	Deutsch	Is a one-bit function constant or balanced?
2	Bernstein-Vazirani	What is the hidden bitstring inside a linear function?
3	Grover	Which item in an unstructured list is marked?
4	Variational algorithms	What is the lowest energy of a Hamiltonian, or a good solution of a combinatorial problem?

ℹ️

Finish Interference before Deutsch. Phase kickback is that lesson, reused as a query.

These procedures are what the application sectors are built from. Chemistry uses the variational loop. Telecommunications and physics use interference and entanglement. Cryptography uses preparation and measurement.