QUROPE Quantum Information Processing and Communication in Europe

M. Gring, M. Kuhnert, T. Langen, D. A. Smith, H.-J. Schmiedmayer (P12 TUWIEN), talk, Relaxation Dynamics and Prethermalization in a Quantum System

R. Amsüss, C. Koller, T. Nöbauer, S. Putz, M. Schramböck, S. Rotter, H.-J. Schmiedmayer, J. Majer (P12 TUWIEN), talk, Hybrid Quantum System: Coupling Color Centers to Superconducting Cavities

S. Van Frank, R. Bücker, J. Grond, S. Manz, T. Berrada, Th. Betz, C. Koller, U. Hohenester, Th. Schumm, A. Perrin, H.-J. Schmiedmayer (P12 TUWIEN), poster, Single mode twin-atom beams

T. Langen, M. Gring, M. Kuhnert, I. Mazets, D. A. Smith, H.-J. Schmiedmayer (P12 TUWIEN), talk, Relaxation Dynamics and Pre-thermalization in a Quantum System

In spontaneous emission an atom in an excited state undergoes a transition to the ground state and emits a single photon. Associated with the emission is a change of the atomic momentum due to photon recoil. Photon emission can be modified close to surfaces and in cavities. For an ion, localized in front of a mirror, coherence of the emitted resonance fluorescence has been reported. Previous experiments demonstrated that spontaneous emission destroys motional coherence.

We numerically model the evolution of a pair of coherently split quasicondensates. A truly one-dimensional case is assumed, so that the loss of the (initially high) coherence between the two quasicondensates is due to dephasing only, but not due to the violation of integrability and subsequent thermalization (which are excluded from the present model).

Imaging ultracold atomic gases close to surfaces is an important tool for the detailed analysis of experiments carried out using atom chips. We describe the critical factors that need be considered, especially when the imaging beam is purposely reflected from the surface. In particular we present methods to measure the atom-surface distance, which is a prerequisite for magnetic field imaging and studies of atom surface-interactions.

Electrons join the growing technology to build integrated quantum circuits that guide matter waves on a chip.

We consider decay of a quasiparticle in a nearly-one-dimensional quasicondensate of trapped atoms, where virtual excitations of transverse modes break down one-dimensionality and integrability, giving rise to effective three-body elastic collisions. We calculate the matrix element for the process that involves one incoming quasiparticle and three outgoing quasiparticles. Scattering that involves low-frequency modes with high thermal population results in a diffusive dynamics of a bunch of quasiparticles created in the system.

Photonic chips that integrate optical elements on a single device can process vast amounts of information rapidly. A new branch of this technology involves coupling light to cold atoms or Bose–Einstein condensates, the quantum nature of which provides a basis for new information-processing methods. The use of optical waveguides gives the light a small cross-section, making coupling to atoms efficient.