Generation Engineering of Heralded Narrowband Colour Entangled States

Efficient heralded generation of entanglement together with its manipulation is of great importance for quantum communications. In addition, states generated with bandwidths naturally compatible with atomic transitions allow a more efficient mapping of light into matter which is an essential requirement for long distance quantum communications. Here we propose a scheme where the indistinguishability between two spontaneous four-wave mixing processes is engineered to herald generation of single-photon frequency-bin entangled states, i.e., single-photons shared by two distinct frequency modes. We show that entanglement can be optimised together with the generation probability, while maintaining absorption negligible. Besides, the scheme illustrated for cold rubidium atoms is versatile and can be implemented in several other physical systems

Muon momentum scale and resolution in pp collisions at s=8 TeV in ATLAS

AbstractThis work shows the performance in the muon momentum scale and resolution achieved by ATLAS during the 2012 run at s=8. The momentum scale is known with an uncertainty ranging from 0.05% (in the central rapidity region) to 0.2% (at large rapidities). The muon momentum resolution is measured to be 1.7% for central muons with low momentum (pT≃10 GeV) and reaches 4% for high-pT muons in the forward regions of the ATLAS detector

Radiation 'damping' in atomic photonic crystals

The force exerted on a material by an incident beam of light is dependent upon the material's velocity in the laboratory frame of reference. This velocity dependence is known to be diffcult to measure, as it is proportional to the incident optical power multiplied by the ratio of the material velocity to the speed of light. Here we show that this typically tiny effect is greatly amplified in multilayer systems composed of resonantly absorbing atoms (e.g. optically trapped 87Rb), which may exhibit ultra-narrow photonic band gaps. The amplification of the effect is shown to be three orders of magnitude greater than previous estimates for conventional photonic-band-gap materials, and significant for material velocities of a few ms/s.Comment: 5 pages, 3 figure

Performance study on the second-level muon trigger of the ATLAS experiment at the LHC

This article will discuss the status and the performances of the second-level muon trigger of the ATLAS experiment at the LHC; to perform these studies, data from the first collisions at √s = 7TeV have been used

Optically Tunable Photonic Stop Bands in Homogeneous Absorbing Media.

Resonantly absorbing media supporting electromagnetically induced transparency may give rise to specific periodic patterns where a light probe is found to experience a fully developed photonic band gap yet with negligible absorption everywhere. In ultracold atomic samples the gap is found to arise from spatial regions where Autler-Townes splitting and electromagnetically induced transparency alternate with one another and detailed calculations show that accurate and efficient coherent optical control of the gap can be accomplished. The remarkable experimental simplicity of the control scheme would ease quantum nonlinear optics applications

Photons on a leash

Quantum coherence and interference can be used to control the light-matter interaction and the propagation of light in multilevel systems. Effects of electromagnetically induced transparency based on exciton and biexciton levels or on impurity levels in solid-state media are here reviewed. New photonic crystal structures created via coherent optical nonlinearities in such solid media are also considered and discusse

Atomic recoil effects in slow light propagation

We theoretically investigate the effect of atomic recoil on the propagation of ultraslow light pulses through a coherently driven Bose-Einstein condensed gas. For a sample at rest, the group velocity of the light pulse is the sum of the group velocity that one would observe in the absence of mechanical effects (infinite mass limit) and the velocity of the recoiling atoms (light-dragging effect). We predict that atomic recoil may give rise to a lower bound for the observable group velocities, as well as to pulse propagation at negative group velocities without appreciable absorption

Slow Light amplification in a non-inverted gain medium

We investigate the propagation of a coherent probe light pulse through a three-level atomic medium (in the $\Lambda$--configuration) in the presence of a pump laser under the conditions for gain without inversion. When the carrier frequency of the probe pulse and the pump laser are in a Raman configuration, we show that it is possible to amplify a slow propagating pulse. We also analyze the regime in which the probe pulse is slightly detuned from resonance where we observe anomalous light propagation.Comment: 7 pages, 10 figures. To be published in Europhysics Letter