In situ measurement of the dynamic structure factor in ultracold quantum   gases
  We propose an experimental setup to efficiently measure the dynamic structure factor of ultracold quantum gases. Our method uses the interaction of the trapped atomic system with two different cavity modes, which are driven by external laser fields. By measuring the output fields of the cavity the dynamic structure factor of the atomic system can be determined. Contrary to previous approaches the atomic system is not destroyed during the measurement process. 
Hendrik Weimer, Hans Peter B\"uchler
cond-mat.quant-gas quant-ph