Abstract By harnessing optical memories based on electromagnetically induced transparency in warm vapors of gaseous alkali metals and cold atomic clouds, this article presents new methods for motion sensing. The proposed scheme for velocimetry can substantially increase the sensitivity of some recent works based on the light-dragging effect in a moving medium, and on the other hand, our proposal, when realized using cold atoms, opens new research questions with regard to limits of light storage in cold atomic clouds. Ultimately, a detailed experimental setup is presented for the realization of the velocimetry scheme using stopped light, which includes considerations for the choice of the medium, laser configuration and control. By investigating the limits of optical memories in motion sensing applications, this research opens up new avenues for employing optical memories beyond applications in quantum information science.
We present an elegant application of matter-wave interferometry to the velocimetry of cold atoms whereby, in analogy to Fourier transform spectroscopy, the one-dimensional velocity distribution is manifest in the frequency domain of the interferometer output. By using stimulated Raman transitions between hyperfine ground states to perform a three-pulse interferometer sequence, we have measured the velocity distributions of clouds of freely expanding
85Rb atoms with temperatures of 34 and $18\phantom{\rule{4pt}{0ex}}\ensuremath{\mu}\mathrm{K}$. Quadrature measurement of the interferometer output as a function of the temporal asymmetry yields velocity distributions with excellent fidelity. Our technique, which is particularly suited to ultracold samples, compares favorably with conventional Doppler and time-of-flight techniques, and it reveals artefacts in standard Raman Doppler methods. The technique is related to, and provides a conceptual foundation of, interferometric matter-wave accelerometry, gravimetry, and rotation sensing.