Quantum physics is concerned with fundamental questions of physics, such as the existence of superposition states or the entanglement of quantum states and the implications of their application. In the period since Max Planck's discoveries, theoretical and experimental research has evolved at an amazing pace and scientists today are capable of controlling quantum systems of photons, of single ions and atoms or small numbers of them with extraordinary precision. The trend of quantum physics towards information technology promises exciting future applications such as the development of quantum computing, quantum cryptography or quantum measuring techniques.