BasePauli Class

[dsvandet]

These notes are related to the BasePauli class from the quantum_info module of qiskit-terra

These notes are in regards to satisfying the following requirement:

• Requirement: An class that represents a Pauli operator

TODO: Link to location of the above requirement
TODO: Unit testing

See general discussion on Pauli operators in he PauliList discussion

Location of Code

Currently these changes are staged at dsvandet/qiskit-terra/tree/paulilist_representations.

Current Modifications to BasePauli Class

The BasePauli class has been modified in the following manner:

• PauliRep has been added as a new base class. PauliRep handles the representations and conversions of representations/formats/syntaxes etc. See PauliRep Class
• Moved and extended the following methods _to_label, _to_matrix, _from_array, _phase_from_label to PauliRep class.
• Improved commutes performance by simply returning np.logical_not(np.sum((x1&other._z)^(z1&other._x),axis=1) % 2) after x1 and z1 are set. Since is is a direct description of the symplectic product it is still readable and faster at the same time.