Unitary Solutions to the Yang-Baxter Equation in Dimension Four
  In this paper, we determine all unitary solutions to the Yang-Baxter equation in dimension four. Quantum computation motivates this study.   This set of solutions will assist in clarifying the relationship between quantum entanglement and topological entanglement.   We present a variety of facts about the Yang-Baxter equation for the reader unfamiliar with the equation. 
H. A. Dye