Quantum gates in QuTiP are unitary operators (or approximately unitary after time evolution). QuTiP provides built-in gates and methods to construct custom gates.

from qutip import *
 
# Pauli gates
X = sigmax()
Y = sigmay()
Z = sigmaz()
 
# Hadamard
H = hadamard_transform()
 
# Phase gates
S = phasegate(np.pi/2)
T = phasegate(np.pi/4)
 
# Rotations
Rx = rx(np.pi/4)   # Rotate π/4 around x
Ry = ry(np.pi/2)   # Rotate π/2 around y
Rz = rz(np.pi/3)   # Rotate π/3 around z

# CNOT (control on qubit 0, target on qubit 1)
CNOT = cnot(2, 0, 1)  # 2 total qubits
 
# Swap
SWAP = swap(2, 0, 1)
 
# Controlled Z
CZ = cz(2, 0, 1)
 
# iSWAP
iSWAP = iswap(2, 0, 1)

Construct unitary gates by time-evolving under a Hamiltonian:

H = 0.5 * sigmaz() + 0.1 * sigmax()
U = (-1j * H * t).expm()  # Matrix exponential: e^{-iHt}
 
# Verify unitarity
print((U.dag() * U).full())  # Should be identity

QuTiP's gate library covers standard quantum computing. Use tensor() to build multi-qubit unitaries.