Editing Quantum logic gate (section)

==== Classical control ====
{{Further|Deferred measurement principle}}
[[File:Example for classic controlled quantum gate.png|thumb|upright=0.8|'''Example:''' The qubit <math>\phi</math> is [[#Measurement|measured]], and the result of this measurement is a [[Boolean data type|Boolean]] value, which is consumed by the classical computer. If <math>\phi</math> measures to 1, then the classical computer tells the quantum computer to apply the U gate on <math>\psi</math>.<br>In circuit diagrams, single lines are [[qubit]]s, and doubled lines are [[bit]]s.]] Gates can also be controlled by classical logic. A quantum computer is controlled by a [[classical computing|classical computer]], and behaves like a [[coprocessor]] that receives instructions from the classical computer about what gates to execute on which qubits.{{r|Oemer|pages=42–43}}<ref name="cryo-controller"/> Classical control is simply the inclusion, or omission, of gates in the instruction sequence for the quantum computer.{{r|Nielsen-Chuang|pages=26–28}}{{r|Williams|pages=87–88}}

{{anchor|Phase shift|Phase shift gates|Phase shift gate|Phase gate}}