Continuous-Variable Quantum Computing in Optical Time-Frequency Modes   using Quantum Memories
  We develop a scheme for time-frequency encoded continuous-variable cluster-state quantum computing using quantum memories. In particular, we propose a method to produce, manipulate and measure 2D cluster states in a single spatial mode by exploiting the intrinsic time-frequency selectivity of Raman quantum memories. Time-frequency encoding enables the scheme to be extremely compact, requiring a number of memories that is a linear function of only the number of different frequencies in which the computational state is encoded, independent of its temporal duration. We therefore show that quantum memories can be a powerful component for scalable photonic quantum information processing architectures. 
Peter C. Humphreys, W. Steven Kolthammer, Joshua Nunn, Marco Barbieri,   Animesh Datta, Ian A. Walmsley
quant-ph