A robust system for Quantum Computation using Coherent Population Trap   states of neutral atoms
  A robust system for use of Quantum Computation using neutral atoms is presented in this communication. This scheme exploits a multilevel atomic system interacting with two lasers in such a way that it leads to formation of two Coherent Population Trap (CPT) states. The atomic population can be pumped alternatively between these two CPT states or any desired superposition of the two can also be formed. These two CPT states can then be mapped to two Qubits for Quantum Computation. Preparation of any desired state and formation of CNOT gates are explained below. A scheme for preparing 1-D lattice of mutually interacting spin systems, which mimic behaviour of magnetic spin systems is also shown. Atoms in CPT states do not interact with the lasers that prepare it and hence are free of perturbation. The states involved here are also made up of only ground states of bare atoms and hence are free of decoherence due to spontaneous emission. Thus, the configuration studied here is a good example of a very robust system. 
Ashok Vudayagiri