Deeply subrecoil two-dimensional Raman cooling

We report the implementation of a two-dimensional Raman cooling scheme using sequential excitations along the orthogonal axes. Using square pulses, we have cooled a cloud of ultracold cesium atoms down to an rms velocity spread of 0.39(5) recoil velocities, corresponding to an effective transverse temperature of $30\mathrm{nK}$ $\left(0.15T_{\mathrm{rec}}\right)$. This technique can be useful to improve cold-atom atomic clocks and is particularly relevant for clocks in microgravity.