qml.grouping.pauli_word_to_string

pauli_word_to_string(pauli_word, wire_map=None)

Convert a Pauli word from a tensor to a string.

Given a Pauli in observable form, convert it into string of characters from ['I', 'X', 'Y', 'Z']. This representation is required for functions such as PauliRot.

Parameters

• pauli_word (Observable) – an observable, either a Tensor instance or single-qubit observable representing a Pauli group element.

• wire_map (dict[Union[str, int], int]) – dictionary containing all wire labels used in the Pauli word as keys, and unique integer labels as their values

Returns

The string representation of the observable in terms of 'I', 'X', 'Y', and/or 'Z'.

Return type

str

Raises

TypeError – if the input observable is not a proper Pauli word.

Example

>>> wire_map = {'a' : 0, 'b' : 1, 'c' : 2}
>>> pauli_word = qml.PauliX('a') @ qml.PauliY('c')
>>> pauli_word_to_string(pauli_word, wire_map=wire_map)
'XIY'