Not sure of what model you have in mind, but simultaneous doesn't seem appropriate: there is definitely a notion of sequence of operations. For example, applyi

Not sure of what model you have in mind, but simultaneous doesn't seem appropriate: there is definitely a notion of sequence of operations. For example, applying the X operator followed by the Y operator on a quantum state |ѱ> can be written as: YX|ѱ> (You don't need to know what X and Y are for the purpose of this example, but think matrix multiplication, X "touching" the state before Y.) RE books, this is a good one: http://www.michaelnielsen.org/qcqi/QINFO-book-nielsen-and-chuang-toc-and-chapter1-nov00.pdf http://www.michaelnielsen.org/qcqi/QINFO-book-nielsen-and-ch...