Theory and Implementation of the Quantum Approximate Optimization
  Algorithm: A Comprehensible Introduction and Case Study Using Qiskit and IBM
  Quantum Computers
The present tutorial aims to provide a comprehensible and easily accessible
introduction into the theory and implementation of the famous Quantum
Approximate Optimization Algorithm (QAOA). We lay our focus on practical
aspects and step-by-step guide through the realization of a proof of concept
quantum application based on a real-world use case. In every step we first
explain the underlying theory and subsequently provide the implementation using
IBM's Qiskit. In this way we provide a thorough understanding of the
mathematical modelling and the (quantum) algorithms as well as the equally
important knowledge how to properly write the code implementing those
theoretical concepts. As another central aspect of this tutorial we provide
extensive experiments on the 27 qubits state-of-the-art quantum computer
ibmq_ehningen. From the discussion of these experiments we gain an overview on
the current status of quantum computers and deduce which problem sizes can
meaningfully be executed on today's hardware.
Andreas Sturm