We present a compact, two-stage atomic beam source that produces a continuous, narrow, collimated, and high-flux beam of rubidium atoms with sub-Doppler temperatures in three dimensions, which features very low emission of near-resonance fluorescence along the atomic trajectory. The atom-beam source originates in a pushed two-dimensional magneto-optical trap (
2D+ MOT) feeding a slightly off-axis three-dimensional moving optical-molasses stage that continuously cools and redirects the atom beam. The capture velocity of the moving optical molasses is deliberately chosen to be low, approximately
3m/s, to reduce fluorescence, and the cooling light is detuned by several atomic linewidths from resonance to reduce the absorption cross section of cooling-induced fluorescence. Near-resonance light from the
2D+ MOT and the push beam does not propagate to the output atomic trajectory due to a ${10}^{\ensuremath{\circ}}$ bend in the atomic trajectory. The atomic beam emitted from the two-stage source has a flux up to $1.6(3)\ifmmode\times\else\texttimes\fi{}{10}^{9}\phantom{\rule{0.2em}{0ex}}\mathrm{atoms}/\mathrm{s}$, with an optimized temperature of $15.0(2)\phantom{\rule{0.2em}{0ex}}\ensuremath{\mu}\mathrm{K}$. We employ continuous Raman-Ramsey interference measurements at the atom-beam output to study the sources of decoherence in the presence of continuous cooling, and demonstrate that the atom-beam source effectively preserves high fringe contrast even during cooling. This cold-atom-beam source is appropriate for use in atom interferometers and clocks, where continuous operation eliminates dead time, the slow atom-beam velocity (6--16 m/s) improves sensitivity, the narrow 3D velocity distribution improves fringe contrast, and the low reabsorption of scattered light mitigates decoherence caused by the continuous cooling process.
We present a compact, single-cell atomic beam source that produces a continuous beam of rubidium atoms with cooling in three dimensions. Our design integrates an off-axis optical molasses into a two-dimensional magnetooptical trap within a single vacuum cell. The 87Rb atom beam source features a flux of 3 × 109 atoms/s, a transverse temperature of 95(5) µK, and a longitudinal temperature of 886(12) µK. We present a temporal coherence theory to evaluate the effect of longitudinal temperature on the inertial measurement performance of atom interferometers. Ultra-low light shift are verified via Raman-Ramsey interferometry, yielding a sensitivity of the center frequency to the MOT laser power is −1.653 × 10−3 Hz/mW. We hope this compact source can contribute to atom-interferometry-based inertial sensors and clocks that are both compact and sensitive.
In atomic sensors, continuous interrogation of laser-cooled atoms carries the benefits of improved sensitivity and high measurement bandwidth. However, cooling in proximity to coherent atomic state evolution can degrade performance in compact systems, due to decoherence. This study demonstrates an inertially sensitive matter-wave interferometer in a three-dimensionally-cooled atomic beam that mitigates decoherence while operating continuously. The technique could enable compact atom-interferometer sensors that measure continuously and with high sensitivity on dynamic platforms.
Through the use of a high-flux rubidium beam source with sub-Doppler temperatures in three dimensions, we have demonstrated an inertially sensitive atom interferometer featuring high contrast, low noise, and continuous measurement with high bandwidth. We describe the cold-atom source and the optical design that optimizes interferometer contrast. Finally, we demonstrate useful features enabled by this architecture, such as continuous phase shear readout and rapid reversal of inertial sensitivity. This demonstration may enable future cold-atom sensors that measure with both high sensitivity and high bandwidth.
Atom interferometers make use of the interference of matter waves for precise measurement of motion. Employing 3D-laser-cooled atoms provides improved fringe contrast, while measuring in a continuous beam architecture provides high-bandwidth measurement, error suppression of time-varying signals, and the elimination of measurement dead time. In this paper, we discuss the initial observation of interference signals in a dual-beam, 3D-cooled atomic beam interferometer architecture. Additionally, we perform initial characterization of the response of the atom interferometer signal to laser intensity and frequency noise.
We present the implementation and characterization of a slow, intense, and collimated rubidium atomic source for atom interferometry. The continuous87Rb cold atomic beam is produced by a new compact two-dimensional magneto-optical trap. And it is based on the 2D+MOT design but a much smaller size and a higher flux compared to our original LVIS system. The on-line detecting system developed over a combination of time-of-flight and fluorescence methods is used to optimize the beam parameters. The dependence of the beam flux on detuning and power are investigated in detail respectively, for cooling and pushing laser. The re-pumping laser power influence is also considered. With aError! Reference source not found.10 G/cm magnetic gradient, 3ΓError! Reference source not found. red detuning from resonance for cooling laser and 5ΓError! Reference source not found. red detuning for pushing laser, the obtained cold atomic beam has a high flux of 4.7×109atoms/s Error! Reference source not found. Error! Reference source not found. It has a narrow longitudinal velocity distribution with mean velocity 10 m/s and full width at half maximum (FWHM)Error! Reference source not found.2 m/sError! Reference source not found. The two-photo stimulated Raman transitions both in Doppler-free and Doppler-sensitive modes are first proceeded, and stable Raman-Ramsey fringes are achieved with twon/2 Error! Reference source not found. Raman pulses.