42 research outputs found

    Experimental Demonstration of a Synthetic Lorentz Force by Using Radiation Pressure

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    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

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    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

    Absolute frequency measurement of the 5s5p 1P1^1P_1 - 5s5d 1D2^1D_2 transition in strontium

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    We report on the absolute frequency determination of the 5s5p 1P1^1P_1 - 5s5d 1D2^1D_2 transition in atomic strontium, achieved through frequency comb-referenced laser-induced-fluorescence (LIF) spectroscopy. We excite the 5s2^2 1S0^1S_0 - 5s5p 1P1^1P_1 transition using an on-resonance laser at \approx461 nm, and then measure the variation in the LIF signal while scanning the laser at \approx767 nm across the 5s5p 1P1^1P_1 - 5s5d 1D2^1D_2 transition. We determine the absolute frequency of 390599571.7±0.4390599571.7\pm0.4 MHz, with an accuracy that surpasses the previous most accurate measurement by two orders of magnitude. This measurement technique can be readily applied for precision spectroscopy of high-lying states not only in strontium, but also in other atomic species

    Two-photon transitions driven by a combination of diode and femtosecond lasers

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    We report on the combined action of a cw diode laser and a train of ultrashort pulses when each of them drives one step of the 5S-5P-5D two-photon transition in rubidium vapor. The fluorescence from the 6P_{3/2} state is detected for a fixed repetition rate of the femtosecond laser while the cw-laser frequency is scanned over the rubidium D_{2} lines. This scheme allows for a velocity selective spectroscopy in a large spectral range including the 5D_{3/2} and 5D_{5/2} states. The results are well described in a simplified frequency domain picture, considering the interaction of each velocity group with the cw laser and a single mode of the frequency comb.Comment: 4 pages, 4 figure

    Frequency-comb-induced radiative force on cold rubidium atoms

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    We experimentally investigate the radiative force and laser-induced fluorescence (LIF) in cold rubidium atoms induced by pulse-train (frequency-comb) excitation. Three configurations are studied: (i) single-pulse-train excitation, (ii) two in-phase counterpropagating pulse trains, and (iii) two out-of-phase counterpropagating pulse trains. In all configurations, measured LIF is in agreement with calculations based on the optical Bloch equations. The observed forces in the first two configurations are in qualitative agreement with the model(s) used for calculating mechanical action of a pulse train on atoms; however, this is not the case for the third configuration. Possible resolution of the discrepancy is discussed

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

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    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 \approx10-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 Λ\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

    Frequency-comb-induced radiation pressure force in dense atomic clouds

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    We investigate the frequency comb induced radiation pressure force acting on a cloud of cold 87^{87}Rb atoms. Reduction and spectral broadening of the frequency comb force are observed as the cloud's optical thickness is increased. Since the radiation pressure force is uniquely determined by light scattered by an atomic cloud, we discuss different scattering mechanisms, and point to the shadow effect as the dominant mechanism affecting FC-induced force in resonantly excited dense atomic clouds. Our results improve the understanding of the interaction of frequency comb light with many-atom ensembles, which is essential for novel frequency comb applications in simultaneous multi-species cooling, multi-mode quantum memories, and multi-mode atom-light interfaces.Comment: 8 pages, 4 figure

    Simultaneous dual-species laser cooling using an optical frequency comb

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    We demonstrate 1D simultaneous laser cooling of 87^{87}Rb and 85^{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^{85,87}Rb atoms at above-Doppler temperatures, we show simultaneous cooling of both species down to the Doppler temperature using two counter-propagating σ\sigma+^{+}/σ\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
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