Quantum circuit diagram of a controlled-Z (CZ) / controlled-sign (CSIGN) / controlled-phase (CPHASE) / controlled-phaseflip (CFP) gate. The gate matrix is (100001000010000−1){\displaystyle \left({\begin{array}{cc}1&amp;0&amp;0&amp;0\\0&amp;1&amp;0&amp;0\\0&amp;0&amp;1&amp;0\\0&amp;0&amp;0&amp;-1\\\end{array}}\right)} in the basis {|00⟩,|01⟩,|10⟩,|11⟩}{\displaystyle \{|00\rangle ,|01\rangle ,|10\rangle ,|11\rangle \}}.
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