> The state of a qubit contains all of its information. This state is frequently expressed as a vector on the Bloch sphere. This state can be changed by applying linear transformations or quantum gates to them. These unitary transformations are described as rotations on the Bloch Sphere. While classical gates correspond to the familiar operations of Boolean logic, quantum gates are physical unitary operators.
Cirq > Operators and Observables: https://quantumai.google/cirq/build/operators
qiskit-terra/qiskit/circuit/operation.py Interface: https://github.com/Qiskit/qiskit-terra/blob/main/qiskit/circ...
tequila/src/tequila/circuit/gates.py: https://github.com/tequilahub/tequila/blob/master/src/tequil...
Pauli matrices > Quantum information: https://en.wikipedia.org/wiki/Pauli_matrices#Quantum_informa...
From Quantum_information#Quantum_information_processing https://en.wikipedia.org/wiki/Quantum_information#Quantum_in... :
> The state of a qubit contains all of its information. This state is frequently expressed as a vector on the Bloch sphere. This state can be changed by applying linear transformations or quantum gates to them. These unitary transformations are described as rotations on the Bloch Sphere. While classical gates correspond to the familiar operations of Boolean logic, quantum gates are physical unitary operators.