3,735 research outputs found
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
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
Muon momentum scale and resolution in pp collisions at s=8Â 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
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
Quasi-periodic Wannier-Stark ladders from driven atomic Bloch oscillations
Periodic Wannier\textendashStark ladder structures of the energy resonances associated with Bloch oscillations can be readily modified into quasi-periodic ones that exhibit peculiar self-similar effects. A compact theoretical description of the dynamics of driven Bloch oscillations is developed here within the quasi-momentum representation. We identify a rather viable scheme based on ultracold atomic wavepackets subject to gravity in a driven optical lattice potential where a self-similar scaling could be observed. Its feasibility in terms of realistic experimental parameters is also discussed
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
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