  This document is a pdf version of the series of blogposts about variational
quantum algorithms (VQA) I originally posted on my blog Musty Thoughts. It
provides an explanation of the basic variational algorithms, such as
Variational Quantum Eigensolver (VQE) and Quantum Approximate Optimization
Algorithm (QAOA), as well as a more general framework for VQAs. It also
describes some more advanced techniques that can be used to make these
algorithms more efficient, as well as the challenges associated with using
them.
