controlled NOT gate

His work in optical quantum computing has included the demonstration of the first optical quantum controlled NOT gate.

For instance, one can use the Controlled NOT gate and the Walsh-Hadamard gate to entangle two qubits.

One simple set of two-qubit universal quantum gates is the Hadamard gate (), the gate , and the controlled NOT gate.

However, a reversible version of the XOR gate-the controlled NOT gate (CNOT)-can be defined by preserving one of the inputs.

Examples of these logic gates which have been studied are the controlled NOT gate (also called CNOT gate), the Toffoli gate and the Fredkin gate.

In computing science, the controlled NOT gate (also C-NOT or CNOT) is a quantum gate that is an essential component in the construction of a quantum computer.

In addition to a regular controlled NOT gate, one could construct a function-controlled NOT gate, which accepts an arbitrary number n+1 of qubits as input, where n+1 is greater than or equal to 2 (a quantum register).

It is equivalent to check (where is addition modulo 2, which can also be viewed as a quantum XOR gate implemented as a Controlled NOT gate), if zero, then is constant, otherwise is not constant.