Probing an atomic gas confined in a nanocell (original) (raw)
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Optical Response of Gas-Phase Atoms at Less thanλ/80from a Dielectric Surface
Physical Review Letters, 2014
We present experimental observations of atom-light interactions within tens of nanometers (down to 11 nm) of a sapphire surface. Using photon counting we detect the fluorescence from of order one thousand Rb or Cs atoms, confined in a vapor with thickness much less than the optical excitation wavelength. The asymmetry in the spectral lineshape provides a direct read-out of the atom-surface potential. A numerical fit indicates a power-law −Cα/r α with α = 3.02 ± 0.06 confirming that the van der Waals interaction dominates over other effects. The extreme sensitivity of our photoncounting technique may allow the search for atom-surface bound states.
Exploring the van der Waals atom-surface attraction in the nanometric range
Europhysics Letters (EPL), 2007
Optical tests of quantum theory 34.50.Dy Interactions of atoms and molecules with surfaces; photon and electron emission; neutralization of ions 32.70.Jz Line shapes, widths, and shifts The van der Waals atom-surface attraction, scaling as C 3 z-3 for z the atom-surface distance, is expected to be valid in the distance range 1-1000 nm, covering 8-10 orders of magnitudes in the interaction energy. A Cs vapour nanocell allows us to analyze the spectroscopic modifications induced by the atom-surface attraction on the 6P 3/2 →6D 5/2 transition. The measured C 3 value is found to be independent of the thickness in the explored range 40-130 nm, and is in agreement with an elementary theoretical prediction. We also discuss the specific interest of exploring short distances and large interaction energy.
Probing the spatial dispersion in a dense atomic vapor near a dielectric interface
Physical Review A, 1998
We have experimentally investigated the selective reflection of the P-D transition in a high-density rubidium vapor and shown it to be sensitive to the exact spatial distribution of P-state atoms near the dielectricvapor interface. This distribution results from the radiative and nonradiative transport of excitation and from wall-quenching collisions of excited-state atoms and is highly inhomogeneous. Selective reflection thus acts as a probe of the spatial dispersion in the vapor. The resulting spectra have been analyzed to show that the broadening due to S-D collisions contributes considerably to the self-broadened linewidth of the P-D transition. ͓S1050-2947͑98͒07712-9͔ PACS number͑s͒: 32.70.Jz, 42.50.Ϫp College Station, TX 77843-4242.
Spectral asymmetry of atoms in the van der Waals potential of an optical nanofiber
Physical Review A, 2018
We measure the modification of the transmission spectra of cold 87 Rb atoms in the proximity of an optical nanofiber (ONF). Van der Waals interactions between the atoms an the ONF surface decrease the resonance frequency of atoms closer to the surface. An asymmetric spectra of the atoms holds information of their spatial distribution around the ONF. We use a far-detuned laser beam coupled to the ONF to thermally excite atoms at the ONF surface. We study the change of transmission spectrum of these atoms as a function of heating laser power. A semiclassical phenomenological model for the thermal excitation of atoms in the atom-surface van der Waals bound states is in good agreement with the measurements. This result suggests that van der Waals potentials could be used to trap and probe atoms at few nanometers from a dielectric surface, a key tool for hybrid photonic-atomic quantum systems.
The European Physical Journal D, 2001
A theory of van der Waals (vdW) interaction between an atom (in ground or excited state) and a birefringent dielectric surface with an arbitrary orientation of the principal optic axis (C-axis) is presented. Our theoretical approach is based on quantum-mechanical linear response theory, using generalized susceptibilities for both atom and electromagnetic field. Resonant atom-surface coupling is predicted for excited-state atoms interacting with a dispersive dielectric surface, when an atom de-excitation channel gets into resonance with a surface polariton mode. In the non-retarded regime, this resonant coupling can lead to enhanced attractive or repulsive vdW surface forces, as well as to a dissipative coupling increasing the excited-state relaxation. We show that the strongly non-scalar character of the interaction with the birefringent surface produces a C-axis-dependent symmetry-breaking of the atomic wavefunction. Changes of the C-axis orientation may also lead to a frequency shift of the surface polariton mode, allowing for tuning on or off the resonant coupling, resulting in a special type of engineering of surface forces. This is analysed here in the case of cesium 6D 3/2 level interacting with a sapphire interface, where it is shown that an adequate choice of the sapphire C-axis orientation allows one to transform vdW surface attraction into repulsion, and to interpret recent experimental observations based on selective reflection methods [H. Failache et al., Phys. Rev. Lett. 83, 5467 (1999)].
Atom Symmetry Break and Metastable Level Coupling in Rare Gas Atom-Surface van der Waals Interaction
Physical Review Letters, 2001
van der Waals interactions between an atom and a planar surface exhibit a quadrupolar component in D 2 z -D 2 ͞3 (D, atomic dipole;ẑ, normal to surface). This coupling is responsible for an atom symmetry break, mixing levels of the same parity such as metastable 3 P 0 , 3 P 2 levels of rare gas atoms. The strongly exoenergic 3 P 0 -3 P 2 transition in Ar and Kr is observed by a time-of-flight technique, using as a surface the edge of a copper slit. The results confirm the predicted strong peaking of the angular distribution of inelastically scattered atoms and give a good estimate of the transition probability.
Spectroscopy of atoms confined to the single node of a standing wave in a parallel-plate cavity
Physical Review A, 1996
We have performed spectroscopy on sodium atoms that are optically channeled in the single node of a laser standing wave set up across a parallel-plate cavity. Using this technique we have extended our previous measurement of the Lennard-Jones van der Waals energy-level shift ͓Sandoghdar et al., Phys. Rev. Lett. 68, 3432 ͑1992͔͒ down to a cavity width of ϳ500 nm. We discuss the applications of this technique to the precise measurement of atom-surface distances.