Computing Library › Quantum Logic Gates
Quantum Logic Gates
√X Gate (SX)
The √X gate is the square root of NOT — apply it twice and you get a bit flip. It is a native gate on much of today's superconducting hardware.
Matrix
Unitary matrix
(1+i)/2(1−i)/2(1−i)/2(1+i)/2
Circuit symbol
Action on basis states
| input | output |
|---|---|
| |0⟩ | half-flip toward |1⟩ |
How it works
SX = √X performs a π/2 rotation about x. Because it is a hardware-native basis gate on many superconducting processors, transpilers decompose arbitrary single-qubit gates into SX and Rz.
In code (Qiskit)
python
qc = QuantumCircuit(1)
qc.sx(0)single-qubitnativerotation