Search results for "Transparency"
showing 10 items of 291 documents
Field-free molecular alignment for probing collisional relaxation dynamics
2013
International audience; We report the experimental study of field-free molecular alignment in CO2 gas mixtures induced by intense femtosecond laser pulses in the presence of collisional processes. We demonstrate that the alignment signals exhibit specific features due to nontrivial collisional propensity rules that tend to preserve the orientation of the rotational angular momentum of the molecules. The analysis is performed with a quantum approach based on the modeling of rotational J- and M-dependent state-to-state transfer rates. The present work paves the way for strong-field spectroscopy of collisional dynamics.
Electromagnetically induced transparency resonances inverted in magnetic field
2015
The electromagnetically induced transparency (EIT) phenomenon has been investigated in a $\Lambda$-system of the $^{87}$Rb D$_1$ line in an external transverse magnetic field. Two spectroscopic cells having strongly different values of the relaxation rates $\gamma_{rel}$ are used: a Rb cell with antirelaxation coating ($L\sim$1 cm) and a Rb nanometric-thin cell (nano-cell) with thickness of the atomic vapor column $L$=795nm. For the EIT in the nano-cell, we have the usual EIT resonances characterized by a reduction in the absorption (i.e. dark resonance (DR)), whereas for the EIT in the Rb cell with an antirelaxation coating, the resonances demonstrate an increase in the absorption (i.e. br…
Electromagnetically Induced Transparency and Light Storage in an Atomic Mott Insulator
2009
We experimentally demonstrate electromagnetically induced transparency and light storage with ultracold 87Rb atoms in a Mott insulating state in a three dimensional optical lattice. We have observed light storage times of about 240 ms, to our knowledge the longest ever achieved in ultracold atomic samples. Using the differential light shift caused by a spatially inhomogeneous far detuned light field we imprint a "phase gradient" across the atomic sample, resulting in controlled angular redirection of the retrieved light pulse.
Manipulation of optical solitons in Bose-Einstein condensates
2004
We propose a method to control the optical transparency of a Bose-Einstein condensate with working energy levels of the Lambda-type. The reported effects are essentially nonlinear and are considered in the framework of an exactly solvable model describing the interaction of light with a Lambda-type medium. We show how the complicated nonlinear interplay between fast and slow solitons in the $\Lambda$-type medium points to a possibility to create optical gates as well as to a possibility to store optical information.
Slowing down of light pulses using backward-wave four-wave mixing with local response
2015
The slowing down of light pulses is achieved using backward-wave four-wave mixing in a medium with local response. A Bi12TiO20 crystal with an external dc field is used in the experiment as a proof-of-concept material. The delay and shape transformation of output pulses are studied and compared for the transmitted and phase conjugate channels. It is shown that the phase conjugate pulse achieves a longer delay under typical experimental conditions with equal intensities of the pump beams. This advantage of the phase conjugate beam is especially pronounced for short pulses with half-widths smaller than the response time of the medium. The agreement of the experimental results with numerical c…
Single-step arbitrary control of mechanical quantum states in ultrastrong optomechanics
2015
We describe how ultrastrong interactions in optomechanical systems can be used to force the system ground state to evolve into an arbitrary quantum state of mechanical motion in a completely controlled and deterministic manner. If the target quantum state is a superposition of $N$ Fock states, it can be obtained by applying in single-step $N$ classical optical signals of different frequencies for a common time interval. This protocol can be applied to various strongly interacting quantum systems as trapped ions beyond the Lamb-Dicke regime and cavity QED into the ultrastrong coupling regime.
Glass physics: still not transparent
1999
Glass is a commonplace word. One immediately thinks of windows or bottles and of properties like brittleness or transparency. However, for a glass blower another feature is more important: glass does not melt abruptly, as a crystal does, but gradually over a range of temperatures. This means that he or she can alter the temperature at which glass solidifies or becomes a liquid by changing the rate at which it is cooled or heated. This is in stark contrast to the behaviour observed when the crystalline form of a material is heated: it will always melt at the same temperature.
Suppression of Hadroproduction in Nuclei
1994
We argue that nuclei are not transparent for fast projectile partons. Color transparency is effective for final state interactions in heavy particle production, though nuclear filtering of initial partons can reduce the cross sections. We show that short-ranged initial state interactions, which have been neglected so far, can be important in hadroproduction on nuclei. With the present scenario of hadroproduction a qualitative description of data can be obtained.
Forward hadron production in pA collisions beyond leading order
2017
In this talk, we report our recent progress on pinning down the cause of negativity in the NLO single inclusive hadron production in pA collisions at forward rapidity.
ϕ meson transparency in nuclei from ϕN resonant interactions
2017
We investigate the $\ensuremath{\phi}$ meson nuclear transparency using some recent theoretical developments on the $\ensuremath{\phi}$ in medium self-energy. The inclusion of direct resonant $\ensuremath{\phi}N$ scattering and the kaon decay mechanisms leads to a $\ensuremath{\phi}$ width much larger than in most previous theoretical approaches. The model has been confronted with photoproduction data from CLAS and LEPS and the recent proton induced $\ensuremath{\phi}$ production from COSY finding an overall good agreement. The results support the need of a quite large direct $\ensuremath{\phi}N$-scattering contribution to the self-energy.