Spectroscopy using thermionic diode detectors

Niemax, K.

doi:10.1007/bf00697477

Cited by 115 publications

(60 citation statements)

References 91 publications

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“…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.…”

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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confidence: 99%

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

et al. 2013

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“…In the experimental temperature range the metal-vapour pressure varied from 1.6 to 9.8 Pa, i.e., the heat-pipe was not operated in heat-pipe mode. In order to utilize the heat-pipe for the thermionic detection of the collisionally produced ions [13], a molybdenum filament 0.25 mm in diameter was built in.…”

Section: Pacs: 3450; 3200mentioning

confidence: 99%

The collision cross sections for the fine-structure mixing of caesium 6P levels induced by collisions with potassium atoms

Horvatić

Vadla

Movre

et al. 1996

Z Phys D - Atoms, Molecules and Clusters

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Abstract.The cross section for the fine-structure excitation transfer Cs(6P~/2) --* Cs(6P3/2), induced by collisions with the ground state potassium atoms, has been measured by resonant Doppler-free two-photon spectroscopy. The population densities of caesium 6Pj (J = 1/2, 3/2) levels were probed by thermionic detection of the collisionally ionized caesium atoms from the Cs(6Pj) -~ Cs(10S1/2) excitation channel. The cross section for the transfer process at the temperaoture T = 503 K 2 0 has been found to be o-(1/2 ~ 3/2) = 45 A + 20 Vo. The result is compared with previously published experimental cross sections for fine-structure transfer in resonance states of other alkali elements perturbed by potassium and a thoeretical value of the Li(2Pj)-K system calculated in a simple approach. PACS:34.50; 32.00The present investigation on excitation energy transfer occuring in the Cs(6P1/2) + K(4S1/2) -~ Cs(6P3/2) + K(4Sz/2) collision process, is part of a series of systematic investigations of the coltisional energy transfer in mixed alkali vapours [1][2][3][4][5][6][7][8]. To our knowledge, this process has never been investigated before. The data published so far in literature on cross sections for fine-structure mixing in alkalis induced by potassium include results for Na*-K [8, 9], K*-K [10-12], and Rb*-K [3] systems. However, these data are so scattered that, for example, a dependence of the cross sections on the fine-structure splittingAEfs of the resonance states can hardly be seen. The present results, although not completing the set of the data for alkali* -K systems, may help to answer the question of the o-vs. AEfs dependence. The missing data for Li*-K system, are very hard to obtain experimentally due to the spectral interference of the Li resonance lines with the potassium B-X molecular band. However, the data can be calculated quite reliably applying a simple but justified model [1, 6].The experimental arrangement, not shown explicitly, was similar to that reported previously [5]. A very small amount of caesium was added to the distilled potassium metal contained in the middle of the stainless steal heatpipe with Pyrex glass windows. The cental region of the heat-pipe was resistively heated to temperatures between 475 K and 530 K. Argon was used as a buffer gas, and its typical pressure, measured by MKS baratron manometer, was 53 Pa. In the experimental temperature range the metal-vapour pressure varied from 1.6 to 9.8 Pa, i.e., the heat-pipe was not operated in heat-pipe mode. In order to utilize the heat-pipe for the thermionic detection of the collisionally produced ions [13], a molybdenum filament 0.25 mm in diameter was built in.Caesium atoms were excited to the 6P1/2 state by the radiation from single-mode frequency stabilized laser diode (Mitsubishi ML 2701, 2 = 895 nm at 24 °C, maximal power: 8 roW). The laser beam was expanded and after passing through the circular aperture (diameter: 2 ram) its power was attenuated by neutral density filters. In order to improve the signal-to-noise ratio of th...

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“…The temperature was measured by calibrated Fe-constantan thermocouple glued beneath the heater to the steel wall with high thermal conductivity cement (Astroceram). The temperature stability was -T 0.2 K. In order to utilize the heat-pipe as the thermionic diode detector for collisionally produced ions [10] cathode filament (0.3 mm in diameter) was built in. The molybdenum has been chosen because it sustained the particular experimental conditions (K vapour atmosphere) with no need for the replacement far better than tungsten.…”

Section: Experiments and Data Analysismentioning

confidence: 99%

“…The first channel is defined by the excitation of the Rb, followed by the collisional transfer to the K, while the second one is direct excitation of the potassium. In both cases the population densities of the excited potassium levels were probed by second excitation step K(4Pj)~ K(7S1/2), and detected using a thermionic-diode technique [10].…”

Section: Introductionmentioning

confidence: 99%

The collision cross sections for excitation energy transfer in Rb(5P 3/2) + K(4S 1/2) → Rb(5S 1/2) + K(4P J ) processes

Horvatić

Vadla

Movre

1993

Z Phys D - Atoms, Molecules and Clusters

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inAbstract. The collisional excitation transfer for the processes Rb*(5P3/2)+K(4SI/2)~Rb(5Sm)+K*(4Pj), J = 1/2, 3/2, was investigated using two-photon laser excitation technique with a thermionic heat-pipe diode as a detector. The population densities of the K 4Pj levels induced by collisions with excited Rb atoms as well as those produced by direct laser excitation of the potassium atoms were probed through the measurement of the thermionic signals generated due to the ionization of the potassium atoms emerging from the K(4Pj) ~ K(7S1/2) excitation channel. The measurements of the thermionic signals in addition to the spectroscopic determination of the potassium number density yield the following values for the excitation transfer cross sections: a 1 (Rb 5 193/2 --~ K 4pro)=8 ~2 and o-2(Rb 5P3/z~K 4P3/2)= 11 ~2 The accuracy of the presented results is T-15%. The obtained results are compared to those for the opposite processes K* (4 Pj) + Rb (5 S~/2) --* K (4 S1/2) + Rb* (5 P3/2).

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Spectroscopy using thermionic diode detectors

Cited by 115 publications

References 91 publications

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

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

The collision cross sections for the fine-structure mixing of caesium 6P levels induced by collisions with potassium atoms

The collision cross sections for excitation energy transfer in Rb(5P 3/2) + K(4S 1/2) → Rb(5S 1/2) + K(4P J ) processes

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Spectroscopy using thermionic diode detectors

Cited by 115 publications

References 91 publications

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

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

The collision cross sections for the fine-structure mixing of caesium 6P levels induced by collisions with potassium atoms

The collision cross sections for excitation energy transfer in Rb*(5P 3/2) + K(4S 1/2) → Rb(5S 1/2) + K*(4P J ) processes

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The collision cross sections for excitation energy transfer in Rb(5P 3/2) + K(4S 1/2) → Rb(5S 1/2) + K(4P J ) processes