Mechanics of Atom Clouds

Edward K. Yeargers

The electronic transition energies from the electron clouds are the same as predicted by the Bohr model. The hydrogen atom, most probable radius of the first quantum mechanical electron cloud is identical to the radius of the first Bohr orbit. The quantum mechanical description goes much further, however. Not only does it predict a series of increasingly larger spherical electron clouds, but other electron cloud series as well. Because of their three dimensional shapes, these electron clouds sometimes are said to describe space states. The analogy to planetary orbits ends when we grasp the fact that quantum mechanical electron clouds are three-dimensional, where a Bohr orbit would be a circle lying entirely in a plane. Quantum mechanics also predicts the ionization energy of the hydrogen atom.

Kanxing Weng, Qi Wang, J. G. Bian +10 more

The initial state of atom clouds significantly influences the performance of cold-atom inertial sensors, particularly for atom gravity gradiometers (AGGs), where the consistency of the initial state of two atom clouds greatly affects measurement performance. By analyzing the mechanism of polarization gradient cooling (PGC), we investigate its effect on the initial velocity consistency of atomic clouds. In the course of this study, we compare different PGC models and identify a model that has the least influence on initial velocity consistency. Based on this model, the velocity difference between the two atom clouds is modulated by various experimental parameters, such as the laser power attenuation time, which ranges from 1 to 6 s with the laser detuning of −88 MHz. The results indicate that the gravity gradient increases by approximately 66.13 E (1 E = 10 −9 s −2 ) for each millimeter per second increase in the velocity difference between the two atomic clouds. The study finds that this velocity difference introduces gravity gradient measurement errors through the two-photon light shift effect. This observation is in excellent agreement with our theoretical calculations. Our study elucidates the mechanism by which the initial velocity difference of atom clouds calibrates instrument measurement errors in AGGs and provides a reference for further enhancing the measurement accuracy of such sensors.

Mateo Kruljac, Danijel Buhin, Domagoj Kovačić +3 more

We investigate the frequency-comb-induced radiation pressure force acting on a cloud of cold 87 R b 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 the 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 multispecies cooling and self-ordering, multimode quantum memories, and quantum computing.

Ernst Grimsehl, Rudolf Tomaschek, L. A. Woodward