What is a quantum gate?
An operation that changes the amplitudes of one or more qubits, the quantum version of a logic gate.
A quantum program is a sequence of gates followed by measurements. Some gates act on one qubit, such as one that turns a plain 0 into an even blend of 0 and 1. Others act on two qubits at once, and those are the ones that create entanglement.
Every gate can be undone by another gate, which is not true of ordinary logic gates. An AND gate that outputs 0 doesn’t tell you which inputs it got.
In the lessonsSee it in a simulation
Related
- QubitThe basic unit of a quantum computer: it can be 0, 1, or a blend of both until it is measured.
- AmplitudeThe number a qubit holds for each possible result. Squaring it gives the chance of that result.
- InterferenceAmplitudes adding up or cancelling when they combine. Quantum algorithms use it to make wrong answers unlikely.
- EntanglementA link between qubits in which their measurement results are correlated in a way no prearranged plan could produce.