# Single-photon induced elementary quantum processes for quantum information processing

## Nils Trautmann

### (Theoretical Quantum Physics, Technical University of Darmstadt)

Time: Tue Dec 8 13:00:00 2015

Location: Building 1, Room 123

The ability to couple single photons efficiently to single material quantum systems, such as atoms or ions, is a key ingredient for quantum information processing. In the first part of the talk, we discuss the influence of the center of mass motion of a trapped two level system on efficient resonant single photon absorption in free space. The center of mass motion can lead to a severe reduction of the coupling efficiency in current experimental implementations.

It is demonstrated that the time dependent modulation of the harmonic trapping frequency allows to squeeze the two level system’s center of mass motion so strongly that almost perfect single photon absorption is possible even in cases of weak confinement by a trapping potential. In the second part of the talk, a scheme for triggering a dissipation dominated highly efficient excitation transfer from a single photon wave packet, with quite arbitrary shape to a single quantum emitter, is presented. Our scheme does not require additional laser pulses or quantum feedback and is not restricted to highly mode selective cavity quantum electrodynamical architectures. We demonstrate the usefulness of our scheme for building a deterministic quantum memory and a deterministic frequency converter between photonic qubits of different wavelengths.