Free rotation around the axes with Rx, Ry, and Rz
While all the phase gates rotate around the z axis to change the phase of the qubit, the rotation gates perform rotations around the respective axes of the Bloch sphere. Rx and Ry rotate the qubit 
angle at the phase angle (
) 0 and 
, and Rz rotates around Z, with the special case of 
and 
, corresponding to the S and T gates.
The R-gates are not their own inverses
As the R-gates perform free rotations around the X, Y, or Z axes, they are not reversible. Adding two of these gates in a row does not negate them. For a quick reminder, see the A quick introduction to quantum gates recipe in Chapter 2, Quantum Computing and Qubits with Python.
Mathematically, the R gates can be expressed as unitary matrixes:
The sample script is available at: https://github.com/PacktPublishing/Quantum-Computing-in-Practice-with-Qiskit-and-IBM-Quantum-Experience/blob...
