Computing Library › Quantum Logic Gates
Quantum Logic Gates
SWAP Gate
The SWAP gate exchanges the states of two qubits — essential for routing information across hardware where qubits aren't all connected.
Matrix
Unitary matrix
1000001001000001
Circuit symbol
Action on basis states
| input | output |
|---|---|
| |01⟩ | |10⟩ |
| |10⟩ | |01⟩ |
How it works
SWAP = three CNOTs. On hardware with limited connectivity, chains of SWAPs move a logical qubit next to its partner before a two-qubit gate — the dominant overhead the transpiler tries to minimize.
In code (Qiskit)
python
qc = QuantumCircuit(2)
qc.swap(0, 1)two-qubitCliffordrouting