Generalized Quantum Control-Not Gate in Two-Spin Ising System
  The physical implementation of the quantum Control-Not gate for a two-spin system is investigated numerically. The concept of a generalized quantum Control-Not gate, with arbitrary phase shift, is introduced. It is shown that a resonant $\pi$-pulse provides a simple example of a generalized quantum Control-Not gate. 
Gennady P. Berman, Gary D. Doolen, Gustavo V. L\'opez, V.I.   Tsifrinovich