Ion traps are systems that are used to trap individual ions in a time varying electric field. Single ions, chains of ions and large ion crystals can be trapped using dynamic electric fields oscillating at a frequency of several MHz. Not only can a single ion be trapped, but a collection of few to several hundred ions can be dynamically trapped in the trapping potential. Using techniques of laser cooling, either a single or a chain of ions can be cooled to the lowest vibrational ground state of the trapping potential. The cooled and trapped ion in the trapping potential approximates very close to a text-book model of a particle in a harmonic potential well. These trapped ions offer a wide range of possibilities in fundamental research as well as for technological applications ranging from building ultra-precise atomic clocks to quantum information processing devices.

In this talk I will introduce the physics and technology of ion traps and give an overview of the current state of the art of various ion trap technologies. I will focus on the manipulation of the internal atomic state as well as the external motional states and how these can be used for quantum information processing.