Experimental Demonstration of a Synthetic Lorentz Force by Using Radiation Pressure

Synthetic magnetism in cold atomic gases opened the doors to many exciting novel physical systems and phenomena. Ubiquitous are the methods used for the creation of synthetic magnetic fields. They include rapidly rotating Bose-Einstein condensates employing the analogy between the Coriolis and the Lorentz force, and laser-atom interactions employing the analogy between the Berry phase and the Aharonov-Bohm phase. Interestingly, radiation pressure - being one of the most common forces induced by light - has not yet been used for synthetic magnetism. We experimentally demonstrate a synthetic Lorentz force, based on the radiation pressure and the Doppler effect, by observing the centre-of-mass motion of a cold atomic cloud. The force is perpendicular to the velocity of the cold atomic cloud, and zero for the cloud at rest. Our novel concept is straightforward to implement in a large volume, for a broad range of velocities, and can be extended to different geometries.Comment: are welcom

Synthetic Lorentz force in classical atomic gases via Doppler effect and radiation pressure

We theoretically predict a novel type of synthetic Lorentz force for classical (cold) atomic gases, which is based on the Doppler effect and radiation pressure. A fairly uniform and strong force can be constructed for gases in macroscopic volumes of several cubic millimeters and more. This opens the possibility to mimic classical charged gases in magnetic fields, such as those in a tokamak, in cold atom experiments.Comment: are welcom

Comparative study of light storage in antirelaxation-coated and buffer-gas-filled alkali vapor cells

We perform a comparative study of light storage in antirelaxation-coated and buffer-gas-filled alkali vapor cells using electromagnetically induced transparency (EIT) in warm rubidium vapor. The use of a buffer-gas-filled cell resulted in $\approx$10-fold improvement in storage time and efficiency compared to antirelaxation-coated cells. We achieve up to sixfold enhancement in buffer-gas-filled memory efficiency, while maintaining a similar memory lifetime, by employing a near-resonant EIT $\Lambda$-scheme instead of a resonant one. Our findings contribute to the development of field-deployable quantum memories. quantum memories.Comment: 8 pages, 6 figure

Simultaneous dual-species laser cooling using an optical frequency comb

We demonstrate 1D simultaneous laser cooling of $^{87}$Rb and $^{85}$Rb atoms using an optical frequency comb. By adjusting the pulse repetition frequency and the offset frequency, the frequency comb spectrum is tuned to ensure that two distinct frequency comb modes are simultaneously red-detuned from the cooling transitions, one mode for each species. Starting from a pre-cooled cloud of $^{85,87}$Rb atoms at above-Doppler temperatures, we show simultaneous cooling of both species down to the Doppler temperature using two counter-propagating $\sigma$$^{+}$/$\sigma$$^{-}$-polarized beams from the frequency comb. The results indicate that simultaneous dual-species frequency comb cooling does not affect the cooling characteristics of individual atomic species. The results of this work imply that several atomic species could be cooled simultaneously using a single frequency comb source. This comb-based multi-channel laser cooling could bring significant advances in multi-species atom interferometers for space applications and in the study of multi-species interactions

Cobra-IE Evaluation by Simulation of the NUPEC BWR Full-Size Fine-Mesh Bundle Test (BFBT)

The COBRA-IE computer code is a thermal-hydraulic subchannel analysis program capable of simulating phenomena present in both PWRs and BWRs. As part of ongoing COBRA-IE assessment efforts, the code has been evaluated against experimental data from the NUPEC BWR Full-Size Fine-Mesh Bundle Tests (BFBT). The BFBT experiments utilized an 8 x 8 rod bundle to simulate BWR operating conditions and power profiles, providing an excellent database for investigation of the capabilities of the code. Benchmarks performed included steady-state and transient void distribution, single-phase and two-phase pressure drop, and steady-state and transient critical power measurements. COBRA-IE effectively captured the trends seen in the experimental data with acceptable prediction error. Future sensitivity studies are planned to investigate the effects of enabling and/or modifying optional code models dealing with void drift, turbulent mixing, rewetting, and CHF

Prospects for precision measurements of atomic helium using direct frequency comb spectroscopy

We analyze several possibilities for precisely measuring electronic transitions in atomic helium by the direct use of phase-stabilized femtosecond frequency combs. Because the comb is self-calibrating and can be shifted into the ultraviolet spectral region via harmonic generation, it offers the prospect of greatly improved accuracy for UV and far-UV transitions. To take advantage of this accuracy an ultracold helium sample is needed. For measurements of the triplet spectrum a magneto-optical trap (MOT) can be used to cool and trap metastable 2^3S state atoms. We analyze schemes for measuring the two-photon $2^3S \to 4^3S$ interval, and for resonant two-photon excitation to high Rydberg states, $2^3S \to 3^3P \to n^3S,D$. We also analyze experiments on the singlet-state spectrum. To accomplish this we propose schemes for producing and trapping ultracold helium in the 1^1S or 2^1S state via intercombination transitions. A particularly intriguing scenario is the possibility of measuring the $1^1S \to 2^1S$ transition with extremely high accuracy by use of two-photon excitation in a magic wavelength trap that operates identically for both states. We predict a ``triple magic wavelength'' at 412 nm that could facilitate numerous experiments on trapped helium atoms, because here the polarizabilities of the 1^1S, 2^1S and 2^3S states are all similar, small, and positive.Comment: Shortened slightly and reformatted for Eur. Phys. J.

7th Drug hypersensitivity meeting: part two

No abstract availabl

Rb

We investigated collisional processes involved in the population of the Rb2 diffuse band through resonant excitation of Rb atoms. Near-infrared (780 nm) and violet (420 nm) diode lasers were used for the Rb first (\rm 5\,^{2}S_{1/2}\to 5\,^{2}P_{3/2}) and second (\rm 5\,^{2}S_{1/2}\to 6\,^{2}P_{3/2}) resonant doublet excitations. Laser induced fluorescence spectra were detected and investigated at different rubidium densities, buffer gas pressures and excitation wavelengths