Simulated quantum process tomography of quantum gates with Rydberg   superatoms
  We have numerically simulated quantum tomography of single-qubit and two-qubit quantum gates with qubits represented by mesoscopic ensembles containing random numbers of atoms. Such ensembles of strongly interacting atoms in the regime of Rydberg blockade are known as Rydberg superatoms. The Stimulated Raman Adiabatic Passage (STIRAP) in the regime of Rydberg blockade is used for deterministic Rydberg excitation in the ensemble, required for storage of quantum information in the collective state of the atomic ensemble and implementation of two-qubit gates. The optimized shapes of the STIRAP pulses are used to achieve high fidelity of the population transfer. Our simulations confirm validity and high fidelity of single-qubit and two-qubit gates with Rydberg superatoms. 
I.I. Beterov, M. Saffman, E.A. Yakshina, D.B. Tretyakov, V.M. Entin,   G.N. Hamzina and I.I. Ryabtsev
quant-ph