Light pulses are an excellent tool to manipulate atoms, so that they move in superposition of different trajectories through space and time. In analogy to the concept of an optical interferometer, these branches can be brought to interference and used as sensors for gravity and other inertial forces. As such, atom interferometry has become a versatile tool technique high-precision quantum metrology, which ranges from gyroscopes to gravitational-wave detection, as well as a testbed for the interface of relativity and quantum mechanics or the detection of dark-matter candidates.
At the same time, atoms not only possess a center-of-mass motion, but also internal degrees of freedom that are the very basis for atomic clocks. Making use of this additional property, one can in principle generate atomic clocks that move in superposition of different branches, interfere with each other, and therefore constitute a different probe of relativistic effects linked to time.
This seminar gives an introduction into the main concepts of atom interferometry and the toolbox necessary to manipulate atoms. While we explain basic examples of atom interferometers, spurious effects like their multipath nature, and state-of-the-art experiments; we also discuss current and ambitious proposals for high-precision tests of fundamental physics.