Experimental realization of double Bragg diffraction: robust   beamsplitters, mirrors, and interferometers for Bose-Einstein condensates
  We present the experimental implementation of double Bragg diffraction of Bose-Einstein condensates (BECs) as proposed in [E. Giese, A. Roura, G. Tackmann, E. M. Rasel, and W. P. Schleich, Phys. Rev. A \textbf{88}, 053608 (2013)]. We excite Rabi oscillations between the three coupled momentum states $\left| 0 \hbar k \right\rangle$ and $\left| \pm 2 \hbar k \right\rangle$. By selecting appropriate interaction times we generate highly efficient beamsplitters and mirrors for Bose-Einstein condensates. In addition, we demonstrate higher-order double Bragg diffraction and display beamsplitters with up to $ \pm 6 \hbar k$ momentum transfer. We compare double Bragg diffraction to several other experimental realizations of beamsplitters. Finally, we show that double Bragg diffraction is well suited for matter wave interferometry by realizing a Ramsey-type interferometer in a quasi one-dimensional waveguide. 
Johannes K\"uber, F. Schmaltz, Gerhard Birkl
cond-mat.quant-gas quant-ph