Controlled NOT gate

In computing science, the controlled NOT gate (also C-NOT or CNOT) is a quantum logic gate that is an essential component in the construction of a gate-based quantum computer. It can be used to entangle and disentangle EPR states. Any quantum circuit can be simulated to an arbitrary degree of accuracy using a combination of CNOT gates and single qubit rotations. In computing science, the controlled NOT gate (also C-NOT or CNOT) is a quantum logic gate that is an essential component in the construction of a gate-based quantum computer. It can be used to entangle and disentangle EPR states. Any quantum circuit can be simulated to an arbitrary degree of accuracy using a combination of CNOT gates and single qubit rotations. The CNOT gate operates on a quantum register consisting of 2 qubits. The CNOT gate flips the second qubit (the target qubit) if and only if the first qubit (the control qubit) is | 1 ⟩ {displaystyle |1 angle } . If one allows only { | 0 ⟩ , | 1 ⟩ } {displaystyle {|0 angle ,|1 angle }} as input values for both qubits, the TARGET output of the CNOT gate corresponds to the result of a classical XOR gate. Fixing CONTROL as | 1 ⟩ {displaystyle |1 angle } , the TARGET output of the CNOT gate yields the result of a classical NOT gate. More generally, the inputs are allowed to be a linear superposition of { | 0 ⟩ , | 1 ⟩ } {displaystyle {|0 angle ,|1 angle }} . The CNOT gate transforms the quantum state: a | 00 ⟩ + b | 01 ⟩ + c | 10 ⟩ + d | 11 ⟩ {displaystyle a|00 angle +b|01 angle +c|10 angle +d|11 angle }