Repeat-until-success cubic phase gate for universal continuous-variable   quantum computation
  In order to achieve universal quantum computation using continuous variables, one needs to jump out of the set of Gaussian operations and have a non-Gaussian element, such as the cubic phase gate. However, such a gate is currently very difficult to implement in practice. Here we introduce an experimentally viable 'repeat-until-success' approach to generating the cubic phase gate, which is achieved using sequential photon subtractions and Gaussian operations. We find that our scheme offers benefits in terms of the expected time until success, although we require a primitive quantum memory. 
Kevin Marshall, Raphael Pooser, George Siopsis, Christian Weedbrook
quant-ph