The Budapest Quantum Optics Group

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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.