2. The existence of Level III depends on one crucial assumption: that the time evolution of the wave function is unitary. 第三个层次的存在，和一个重要的假设有关：波函数随时间的演化是么正的。
3. We introduce some important matrices and their applications in quantum computation and quantum information, including density matrix, unitary matrix, etc. 介绍了量子计算与量子信息中的一些重要的矩阵及其应用，包括密度矩阵、酉矩阵等。
英英解释
adj.
1. relating to or characterized by or aiming toward unity
2. of or pertaining to or involving the use of units
3. characterized by or constituting a form of government in which power is held by one central authorit
4. having the indivisible character of a unit
