PauliList#

class qiskit.quantum_info.PauliList(data)[código fonte]#

Bases: BasePauli, LinearMixin, GroupMixin

List of N-qubit Pauli operators.

This class is an efficient representation of a list of Pauli operators. It supports 1D numpy array indexing returning a Pauli for integer indexes or a PauliList for slice or list indices.

Initialization

A PauliList object can be initialized in several ways.

PauliList(list[str])
where strings are same representation with Pauli.

PauliList(Pauli) and PauliList(list[Pauli])
where Pauli is Pauli.

PauliList.from_symplectic(z, x, phase)
where z and x are 2 dimensional boolean numpy.ndarrays and phase is an integer in [0, 1, 2, 3].

For example,

import numpy as np

from qiskit.quantum_info import Pauli, PauliList

# 1. init from list[str]
pauli_list = PauliList(["II", "+ZI", "-iYY"])
print("1. ", pauli_list)

pauli1 = Pauli("iXI")
pauli2 = Pauli("iZZ")

# 2. init from Pauli
print("2. ", PauliList(pauli1))

# 3. init from list[Pauli]
print("3. ", PauliList([pauli1, pauli2]))

# 4. init from np.ndarray
z = np.array([[True, True], [False, False]])
x = np.array([[False, True], [True, False]])
phase = np.array([0, 1])
pauli_list = PauliList.from_symplectic(z, x, phase)
print("4. ", pauli_list)

 ['II', 'ZI', '-iYY']
 ['iXI']
 ['iXI', 'iZZ']
 ['YZ', '-iIX']

Data Access

The individual Paulis can be accessed and updated using the [] operator which accepts integer, lists, or slices for selecting subsets of PauliList. If integer is given, it returns Pauli not PauliList.

pauli_list = PauliList(["XX", "ZZ", "IZ"])
print("Integer: ", repr(pauli_list[1]))
print("List: ", repr(pauli_list[[0, 2]]))
print("Slice: ", repr(pauli_list[0:2]))

Integer:  Pauli('ZZ')
List:  PauliList(['XX', 'IZ'])
Slice:  PauliList(['XX', 'ZZ'])

Iteration

Rows in the Pauli table can be iterated over like a list. Iteration can also be done using the label or matrix representation of each row using the label_iter() and matrix_iter() methods.

Initialize the PauliList.

Parâmetros:: data (Pauli or list) – input data for Paulis. If input is a list each item in the list must be a Pauli object or Pauli str.
Levanta:: QiskitError – if input array is invalid shape.

Additional Information:: The input array is not copied so multiple Pauli tables can share the same underlying array.

Attributes

dim#: Return tuple (input_shape, output_shape).

num_qubits#: Return the number of qubits if a N-qubit operator or None otherwise.

phase#: Return the phase exponent of the PauliList.

qargs#: Return the qargs for the operator.

settings#: Return settings.

shape#: The full shape of the array()

size#: The number of Pauli rows in the table.

x#: The x array for the symplectic representation.

z#: The z array for the symplectic representation.

Methods

adjoint()[código fonte]#: Return the adjoint of each Pauli in the list.

anticommutes(other, qargs=None)[código fonte]#

Return True if other Pauli that anticommutes with other.

Parâmetros:

other (PauliList) – another PauliList operator.
qargs (list) – qubits to apply dot product on (default: None).

Retorno:

True if Paulis anticommute, False if they commute.

Tipo de retorno:

bool

anticommutes_with_all(other)[código fonte]#

Return indexes of rows that commute other.

If other is a multi-row Pauli list the returned vector indexes rows of the current PauliList that anti-commute with all Paulis in other. If no rows satisfy the condition the returned array will be empty.

Parâmetros:: other (PauliList) – a single Pauli or multi-row PauliList.
Retorno:: index array of the anti-commuting rows.
Tipo de retorno:: array

argsort(weight=False, phase=False)[código fonte]#

Return indices for sorting the rows of the table.

The default sort method is lexicographic sorting by qubit number. By using the weight kwarg the output can additionally be sorted by the number of non-identity terms in the Pauli, where the set of all Paulis of a given weight are still ordered lexicographically.

Parâmetros:

weight (bool) – Optionally sort by weight if True (Default: False).
phase (bool) – Optionally sort by phase before weight or order (Default: False).

Retorno:

the indices for sorting the table.

Tipo de retorno:

array

commutes(other, qargs=None)[código fonte]#

Return True for each Pauli that commutes with other.

Parâmetros:

other (PauliList) – another PauliList operator.
qargs (list) – qubits to apply dot product on (default: None).

Retorno:

True if Paulis commute, False if they anti-commute.

Tipo de retorno:

bool

commutes_with_all(other)[código fonte]#

Return indexes of rows that commute other.

If other is a multi-row Pauli list the returned vector indexes rows of the current PauliList that commute with all Paulis in other. If no rows satisfy the condition the returned array will be empty.

Parâmetros:: other (PauliList) – a single Pauli or multi-row PauliList.
Retorno:: index array of the commuting rows.
Tipo de retorno:: array

compose(other, qargs=None, front=False, inplace=False)[código fonte]#

Return the composition self∘other for each Pauli in the list.

Parâmetros:

other (PauliList) – another PauliList.
qargs (None or list) – qubits to apply dot product on (Default: None).
front (bool) – If True use dot composition method [default: False].
inplace (bool) – If True update in-place (default: False).

Retorno:

the list of composed Paulis.

Tipo de retorno:

PauliList

Levanta:

QiskitError – if other cannot be converted to a PauliList, does not have either 1 or the same number of Paulis as the current list, or has the wrong number of qubits for the specified qargs.

conjugate()[código fonte]#: Return the conjugate of each Pauli in the list.

copy()#: Make a deep copy of current operator.

delete(ind, qubit=False)[código fonte]#

Return a copy with Pauli rows deleted from table.

When deleting qubits the qubit index is the same as the column index of the underlying X and Z arrays.

Parâmetros:

ind (int or list) – index(es) to delete.
qubit (bool) – if True delete qubit columns, otherwise delete Pauli rows (Default: False).

Retorno:

the resulting table with the entries removed.

Tipo de retorno:

PauliList

Levanta:

QiskitError – if ind is out of bounds for the array size or number of qubits.

dot(other, qargs=None, inplace=False)[código fonte]#

Return the composition other∘self for each Pauli in the list.

Parâmetros:

other (PauliList) – another PauliList.
qargs (None or list) – qubits to apply dot product on (Default: None).
inplace (bool) – If True update in-place (default: False).

Retorno:

the list of composed Paulis.

Tipo de retorno:

PauliList

Levanta:

QiskitError – if other cannot be converted to a PauliList, does not have either 1 or the same number of Paulis as the current list, or has the wrong number of qubits for the specified qargs.

equiv(other)[código fonte]#

Entrywise comparison of Pauli equivalence up to global phase.

Parâmetros:

other (PauliList or Pauli) – a comparison object.

Retorno:

An array of True or False for entrywise equivalence: of the current table.

Tipo de retorno:

np.ndarray

evolve(other, qargs=None, frame='h')[código fonte]#

Performs either Heisenberg (default) or Schrödinger picture evolution of the Pauli by a Clifford and returns the evolved Pauli.

Schrödinger picture evolution can be chosen by passing parameter frame='s'. This option yields a faster calculation.

Heisenberg picture evolves the Pauli as \(P^\prime = C^\dagger.P.C\).

Schrödinger picture evolves the Pauli as \(P^\prime = C.P.C^\dagger\).

Parâmetros:

other (Pauli or Clifford or QuantumCircuit) – The Clifford operator to evolve by.
qargs (list) – a list of qubits to apply the Clifford to.
frame (string) – 'h' for Heisenberg (default) or 's' for Schrödinger framework.

Retorno:

the Pauli \(C^\dagger.P.C\) (Heisenberg picture) or the Pauli \(C.P.C^\dagger\) (Schrödinger picture).

Tipo de retorno:

PauliList

Levanta:

QiskitError – if the Clifford number of qubits and qargs don’t match.

expand(other)[código fonte]#

Return the expand product of each Pauli in the list.

Parâmetros:: other (PauliList) – another PauliList.
Retorno:: the list of tensor product Paulis.
Tipo de retorno:: PauliList
Levanta:: QiskitError – if other cannot be converted to a PauliList, does not have either 1 or the same number of Paulis as the current list.

classmethod from_symplectic(z, x, phase=0)[código fonte]#

Construct a PauliList from a symplectic data.

Parâmetros:

z (np.ndarray) – 2D boolean Numpy array.
x (np.ndarray) – 2D boolean Numpy array.
phase (np.ndarray or None) – Optional, 1D integer array from Z_4.

Retorno:

the constructed PauliList.

Tipo de retorno:

PauliList

group_commuting(qubit_wise=False)[código fonte]#

Partition a PauliList into sets of commuting Pauli strings.

Parâmetros:

qubit_wise (bool) –

whether the commutation rule is applied to the whole operator, or on a per-qubit basis. For example:

>>> from qiskit.quantum_info import PauliList
>>> op = PauliList(["XX", "YY", "IZ", "ZZ"])
>>> op.group_commuting()
[PauliList(['XX', 'YY']), PauliList(['IZ', 'ZZ'])]
>>> op.group_commuting(qubit_wise=True)
[PauliList(['XX']), PauliList(['YY']), PauliList(['IZ', 'ZZ'])]

Retorno:

List of PauliLists where each PauliList contains commuting Pauli operators.

Tipo de retorno:

list[PauliList]

group_qubit_wise_commuting()[código fonte]#

Partition a PauliList into sets of mutually qubit-wise commuting Pauli strings.

Retorno:: List of PauliLists where each PauliList contains commutable Pauli operators.
Tipo de retorno:: list[PauliList]

input_dims(qargs=None)#: Return tuple of input dimension for specified subsystems.

insert(ind, value, qubit=False)[código fonte]#

Insert Paulis into the table.

When inserting qubits the qubit index is the same as the column index of the underlying X and Z arrays.

Parâmetros:

ind (int) – index to insert at.
value (PauliList) – values to insert.
qubit (bool) – if True insert qubit columns, otherwise insert Pauli rows (Default: False).

Retorno:

the resulting table with the entries inserted.

Tipo de retorno:

PauliList

Levanta:

QiskitError – if the insertion index is invalid.

inverse()[código fonte]#: Return the inverse of each Pauli in the list.

label_iter()[código fonte]#

Return a label representation iterator.

This is a lazy iterator that converts each row into the string label only as it is used. To convert the entire table to labels use the to_labels() method.

Retorno:: label iterator object for the PauliList.
Tipo de retorno:: LabelIterator

matrix_iter(sparse=False)[código fonte]#

Return a matrix representation iterator.

This is a lazy iterator that converts each row into the Pauli matrix representation only as it is used. To convert the entire table to matrices use the to_matrix() method.

Parâmetros:: sparse (bool) – optionally return sparse CSR matrices if True, otherwise return Numpy array matrices (Default: False)
Retorno:: matrix iterator object for the PauliList.
Tipo de retorno:: MatrixIterator

output_dims(qargs=None)#: Return tuple of output dimension for specified subsystems.

power(n)#

Return the compose of a operator with itself n times.

Parâmetros:: n (int) – the number of times to compose with self (n>0).
Retorno:: the n-times composed operator.
Tipo de retorno:: Pauli
Levanta:: QiskitError – if the input and output dimensions of the operator are not equal, or the power is not a positive integer.

reshape(input_dims=None, output_dims=None, num_qubits=None)#

Return a shallow copy with reshaped input and output subsystem dimensions.

Parâmetros:

input_dims (None or tuple) – new subsystem input dimensions. If None the original input dims will be preserved [Default: None].
output_dims (None or tuple) – new subsystem output dimensions. If None the original output dims will be preserved [Default: None].
num_qubits (None or int) – reshape to an N-qubit operator [Default: None].

Retorno:

returns self with reshaped input and output dimensions.

Tipo de retorno:

BaseOperator

Levanta:

QiskitError – if combined size of all subsystem input dimension or subsystem output dimensions is not constant.

sort(weight=False, phase=False)[código fonte]#

Sort the rows of the table.

Example

Consider sorting all a random ordering of all 2-qubit Paulis

from numpy.random import shuffle
from qiskit.quantum_info.operators import PauliList

# 2-qubit labels
labels = ['II', 'IX', 'IY', 'IZ', 'XI', 'XX', 'XY', 'XZ',
          'YI', 'YX', 'YY', 'YZ', 'ZI', 'ZX', 'ZY', 'ZZ']
# Shuffle Labels
shuffle(labels)
pt = PauliList(labels)
print('Initial Ordering')
print(pt)

# Lexicographic Ordering
srt = pt.sort()
print('Lexicographically sorted')
print(srt)

# Weight Ordering
srt = pt.sort(weight=True)
print('Weight sorted')
print(srt)

Initial Ordering
['YX', 'ZZ', 'XZ', 'YI', 'YZ', 'II', 'XX', 'XI', 'XY', 'YY', 'IX', 'IZ',
 'ZY', 'ZI', 'ZX', 'IY']
Lexicographically sorted
['II', 'IX', 'IY', 'IZ', 'XI', 'XX', 'XY', 'XZ', 'YI', 'YX', 'YY', 'YZ',
 'ZI', 'ZX', 'ZY', 'ZZ']
Weight sorted
['II', 'IX', 'IY', 'IZ', 'XI', 'YI', 'ZI', 'XX', 'XY', 'XZ', 'YX', 'YY',
 'YZ', 'ZX', 'ZY', 'ZZ']

Parâmetros:

weight (bool) – optionally sort by weight if True (Default: False).
phase (bool) – Optionally sort by phase before weight or order (Default: False).

Retorno:

a sorted copy of the original table.

Tipo de retorno:

PauliList

tensor(other)[código fonte]#

Return the tensor product with each Pauli in the list.

Parâmetros:: other (PauliList) – another PauliList.
Retorno:: the list of tensor product Paulis.
Tipo de retorno:: PauliList
Levanta:: QiskitError – if other cannot be converted to a PauliList, does not have either 1 or the same number of Paulis as the current list.

to_labels(array=False)[código fonte]#

Convert a PauliList to a list Pauli string labels.

For large PauliLists converting using the array=True kwarg will be more efficient since it allocates memory for the full Numpy array of labels in advance.

Table 3 Pauli Representations#
Label	Symplectic	Matrix
`"I"`	\([0, 0]\)	\(\begin{bmatrix} 1 & 0 \\ 0 & 1 \end{bmatrix}\)
`"X"`	\([1, 0]\)	\(\begin{bmatrix} 0 & 1 \\ 1 & 0 \end{bmatrix}\)
`"Y"`	\([1, 1]\)	\(\begin{bmatrix} 0 & -i \\ i & 0 \end{bmatrix}\)
`"Z"`	\([0, 1]\)	\(\begin{bmatrix} 1 & 0 \\ 0 & -1 \end{bmatrix}\)

Parâmetros:: array (bool) – return a Numpy array if True, otherwise return a list (Default: False).
Retorno:: The rows of the PauliList in label form.
Tipo de retorno:: list or array

to_matrix(sparse=False, array=False)[código fonte]#

Convert to a list or array of Pauli matrices.

For large PauliLists converting using the array=True kwarg will be more efficient since it allocates memory a full rank-3 Numpy array of matrices in advance.

Table 4 Pauli Representations#
Label	Symplectic	Matrix
`"I"`	\([0, 0]\)	\(\begin{bmatrix} 1 & 0 \\ 0 & 1 \end{bmatrix}\)
`"X"`	\([1, 0]\)	\(\begin{bmatrix} 0 & 1 \\ 1 & 0 \end{bmatrix}\)
`"Y"`	\([1, 1]\)	\(\begin{bmatrix} 0 & -i \\ i & 0 \end{bmatrix}\)
`"Z"`	\([0, 1]\)	\(\begin{bmatrix} 1 & 0 \\ 0 & -1 \end{bmatrix}\)

Parâmetros:

sparse (bool) – if True return sparse CSR matrices, otherwise return dense Numpy arrays (Default: False).
array (bool) – return as rank-3 numpy array if True, otherwise return a list of Numpy arrays (Default: False).

Retorno:

A list of dense Pauli matrices if array=False` and ``sparse=False`. list: A list of sparse Pauli matrices if ``array=False and sparse=True. array: A dense rank-3 array of Pauli matrices if array=True.

Tipo de retorno:

list

transpose()[código fonte]#: Return the transpose of each Pauli in the list.

unique(return_index=False, return_counts=False)[código fonte]#

Return unique Paulis from the table.

Example

from qiskit.quantum_info.operators import PauliList

pt = PauliList(['X', 'Y', '-X', 'I', 'I', 'Z', 'X', 'iZ'])
unique = pt.unique()
print(unique)

['X', 'Y', '-X', 'I', 'Z', 'iZ']

Parâmetros:

return_index (bool) – If True, also return the indices that result in the unique array. (Default: False)
return_counts (bool) – If True, also return the number of times each unique item appears in the table.

Retorno:

unique: the table of the unique rows.
unique_indices: np.ndarray, optional: The indices of the first occurrences of the unique values in the original array. Only provided if return_index is True.
unique_counts: np.array, optional: The number of times each of the unique values comes up in the original array. Only provided if return_counts is True.

Tipo de retorno:

PauliList