Measurement and modelling of intensity dependent absorption and transit relaxation on the cesium line

Sagle, J.; Namiotka, R. K.; Huennekens, J.

doi:10.1088/0953-4075/29/12/023

Cited by 81 publications

(57 citation statements)

References 18 publications

(30 reference statements)

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“…Importantly we show that our model predicts that the spatial variation of the optically pumped atomic populations will differ from that of the spatial dependence of the probing laser beam intensity. As atoms move through the beam, we see in our simulations a wake of excited atoms: The steady-state atomic populations are modified from their thermal equilibrium values by the nearby laser beam, a phenomenon which seems to have been overlooked in other work [19,23,25].…”

Section: Introductionmentioning

confidence: 74%

“…A common approach was the addition of a phenomenological relaxation rate between formally stable ground-state levels to account for beam transit effects (Ref. [23] and references therein). A number of numerically intensive models were also presented to solve the full density matrix model in the time domain [20,21,24]; however, those approaches have not taken into account the scattering of the light field by the atoms and the resulting evolution in intensity along the beam axis.…”

Section: Introductionmentioning

confidence: 99%

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Theory of spectroscopy in an optically pumped effusive vapor

Stace

Luiten

2010

Phys. Rev. A

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We present a theoretical framework for studying spatially dependent absorption in a thermal vapor of multilevel atoms, of arbitrary optical thickness. The atomic state dynamics, governed by a standard atom-optical master equation, are self-consistently coupled to the axial evolution of the probe beam intensity and the effusive gas dynamics. We derive steady-state equations for the spatially varying distributions of atomic populations and the probe beam intensity. From the latter, absorption coefficients in both the saturated and unsaturated regimes can be calculated. We present solutions to the resulting equations at various levels of approximation, including an example of the full numerical solution of a saturated, optically thick vapor of three-level atoms, demonstrating a breakdown of Beer's law, among other measurable effects.

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Section: Introductionmentioning

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Theory of spectroscopy in an optically pumped effusive vapor

Stace

Luiten

2010

Phys. Rev. A

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“…• C [20]. The ionization rate was estimated from the observed width of the EIT signal to be Γ ion = 50 × 2π MHz.…”

mentioning

confidence: 99%

Electrical Readout for Coherent Phenomena Involving Rydberg Atoms in Thermal Vapor Cells

et al. 2013

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We present a very sensitive and scalable method to measure the population of highly excited Rydberg states in a thermal vapor cell of rubidium atoms. We detect the Rydberg ionization current in a 5 mm electrically contacted cell. The measured current is found to be in excellent agreement with a theory for the Rydberg population based on a master equation for the three level problem including an ionization channel and the full Doppler distributions at the corresponding temperatures. The signal-to-noise ratio of the current detection is substantially better than purely optical techniques.PACS numbers: 32.80. Rm, 03.67.Lx, 42.50.Gy Coherent phenomena involving strongly interacting Rydberg atoms have recently led to the demonstration of first quantum devices like quantum logic gates [1][2][3] and single photon sources [4] based on ultracold atoms. All these experiments require precise control over the highly excited states populations, which can be probed directly by field ionization [5,6] or by fluorescence techniques involving Rydberg shielding [7]. Since the strong vdW interaction has recently also been observed in vapor cells [8], scalable quantum devices based on the Rydberg blockade in above room temperature ensembles seem to be also within reach [9]. However, ion detectors as electron multipliers or multi-channel plates cannot be used in dense thermal vapors. For this reason, in thermal cells, most studies today use an indirect measurement of the excited state population by analyzing light fields leaving the atomic ensemble. Nevertheless, it is desirable to study not only the back-action of the vapor on the light, typically via electromagnetically induced transparency (EIT) [10], but also to measure directly the number of excited Rydberg states. One method, developed almost a century ago [11,12], makes use of thermionic diodes [13][14][15]. There, one of the electrodes is heated to emit electrons, which produce space charge limited gain for the amplification of ionized Rydberg atoms. The need of long ion trapping times requires large geometries for the space charge region, and an additional shielded excitation region to minimize the effect of disturbing electric fields during excitation of the highly polarizable Rydberg atoms. Despite its high sensitivity, this drawback sets a practical limitation for further applications where size and scalability play a role.Here we demonstrate that, in a symmetric configuration of atomic vapor between two transparent field plates, sizable currents in the nA regime reflect directly the Rydberg population and can be used as a probe with very good signal-to-noise ratio. This opens unique possibilities to probe very efficiently small spectroscopic features involving Rydberg states in thermal vapor but also might be used to stabilize lasers. By extending this concept to an array of pixel-wise arranged electrodes, high resolution spatial information on the Rydberg population can be obtained.The experiments were performed with the setup schematically shown in Fig. 1. The Rb va...

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“…As a result the measured absorption signal is being reduced; the depopulation however is not to be recognized in the absorption profile. In order to test the relevance of such an effect, the laser light can be attenuated by neutral density filters: with increasing attenuation the absorption signal saturates, as described in [31].…”

Section: Depopulation Of the Ground State Densitymentioning

confidence: 99%

“…For the determination of the ground state depopulation, the depletion of the individual hyperfine structure lines has to be taken into account [31]. Since for the analysis the integral of all hyperfine components is used it is sufficient to obtain the correction for the full D 2 line.…”

Section: Calibration At the Caesium Reference Cellmentioning

confidence: 99%

Optimizing the laser absorption technique for quantification of caesium densities in negative hydrogen ion sources

Fantz¹,

Wimmer²

2011

J. Phys. D: Appl. Phys.

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To cite this version:U Fantz, C Wimmer. Optimizing the laser absorption technique for quantification of caesium densities in negative hydrogen ion sources. Journal of Physics D: Applied Physics, IOP Publishing, 2011, 44 (33) Abstract. The performance of negative hydrogen ion sources, which rely on the formation of negative hydrogen ions on a surface with low work function, depends strongly on the caesium dynamics in the source. A quantitative measurement of the amount of caesium in the source during plasma-on and plasma-off (vacuum phase) is highly desirable. The laser absorption technique is optimized for the diagnostics of neutral caesium densities close to the extraction surface on which the negative hydrogen ions are generated. The setup has been simplified as much as possible utilizing also an automatic data evaluation for online measurements at high power rf sources. The setup has been tested and calibrated in a small scale laboratory experiment. The system and the analysis of the D 2 caesium line at 852.1 nm is described in detail, including effects of line saturation and density depletion. The system is sensitive in the density range of 10 13 -10 17 m -3 (path length of about 15 cm), allowing also for a temporal resolution of 40 ms. First very promising results from the negative hydrogen ion source are presented, such as the increase of the caesium density due to the caesium evaporation and time traces before, during, and after the discharge indicating a strong caesium redistribution.

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Measurement and modelling of intensity dependent absorption and transit relaxation on the cesium line

Cited by 81 publications

References 18 publications

Theory of spectroscopy in an optically pumped effusive vapor

Theory of spectroscopy in an optically pumped effusive vapor

Electrical Readout for Coherent Phenomena Involving Rydberg Atoms in Thermal Vapor Cells

Optimizing the laser absorption technique for quantification of caesium densities in negative hydrogen ion sources

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