A Novel, Robust Quantum Detection Scheme
  Protocols used in quantum information and precision spectroscopy rely on efficient internal quantum state discrimination. With a single ion in a linear Paul trap, we implement a novel detection method which utilizes correlations between two detection events with an intermediate spin-flip. The technique is experimentally characterized as more robust against fluctuations in detection laser power compared to conventionally implemented methods. Furthermore, systematic detection errors which limit the Rabi oscillation contrast in conventional methods are overcome. 
Boerge Hemmerling and Florian Gebert and Yong Wan and Piet O. Schmidt
quant-ph