StabilizerTable
class StabilizerTable(data, phase=None)
Bases: qiskit.quantum_info.operators.symplectic.pauli_table.PauliTable
, qiskit.quantum_info.operators.mixins.adjoint.AdjointMixin
Symplectic representation of a list Stabilizer matrices.
Symplectic Representation
The symplectic representation of a single-qubit Stabilizer matrix is a pair of boolean values and a boolean phase p such that the Stabilizer matrix is given by . The correspondence between labels, symplectic representation, stabilizer matrices, and Pauli matrices for the single-qubit case is shown in the following table.
Label | Phase | Symplectic | Matrix | Pauli |
---|---|---|---|---|
"+I" | 0 | |||
"-I" | 1 | |||
"X" | 0 | |||
"-X" | 1 | |||
"Y" | 0 | |||
"-Y" | 1 | |||
"Z" | 0 | |||
"-Z" | 1 |
Internally this is stored as a length N boolean phase vector and a PauliTable
boolean matrix:
where each row is a block vector with , is the symplectic representation of an N-qubit Pauli. This representation is based on reference [1].
StabilizerTable’s can be created from a list of labels using from_labels()
, and converted to a list of labels or a list of matrices using to_labels()
and to_matrix()
respectively.
Group Product
The product of the stabilizer elements is defined with respect to the matrix multiplication of the matrices in Table 1. In terms of stabilizes labels the dot product group structure is
A.B | I | X | Y | Z |
---|---|---|---|---|
I | I | X | Y | Z |
X | X | I | -Z | Y |
Y | Y | Z | -I | -X |
Z | Z | -Y | X | I |
The dot()
method will return the output for row.dot(col) = row.col
, while the compose()
will return row.compose(col) = col.row
from the above table.
Note that while this dot product is different to the matrix product of the PauliTable
, it does not change the commutation structure of elements. Hence commutes:()
will be the same for the same labels.
Qubit Ordering
The qubits are ordered in the table such the least significant qubit [x_{i, 0}, z_{i, 0}] is the first element of each of the vector blocks. This is the opposite order to position in string labels or matrix tensor products where the least significant qubit is the right-most string character. For example Pauli "ZX"
has "X"
on qubit-0 and "Z"
on qubit 1, and would have symplectic vectors , .
Data Access
Subsets of rows can be accessed using the list access []
operator and will return a table view of part of the StabilizerTable. The underlying phase vector and Pauli array can be directly accessed using the phase
and array
properties respectively. The sub-arrays for only the X or Z blocks can be accessed using the X
and Z
properties respectively.
The Pauli part of the Stabilizer table can be viewed and accessed as a PauliTable
object using the pauli
property. Note that this doesn’t copy the underlying array so any changes made to the Pauli table will also change the stabilizer table.
Iteration
Rows in the Stabilizer 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.
References
- S. Aaronson, D. Gottesman, Improved Simulation of Stabilizer Circuits, Phys. Rev. A 70, 052328 (2004). arXiv:quant-ph/0406196
Initialize the StabilizerTable.
Parameters
- data (array or str or PauliTable) – input PauliTable data.
- phase (array or bool or None) – optional phase vector for input data (Default: None).
Raises
QiskitError – if input array or phase vector has an invalid shape.
Additional Information:
The input array is not copied so multiple Pauli and Stabilizer tables can share the same underlying array.
Methods
adjoint
StabilizerTable.adjoint()
Return the adjoint of the Operator.
anticommutes_with_all
StabilizerTable.anticommutes_with_all(other)
Return indexes of rows that commute other.
If other is a multi-row Pauli table the returned vector indexes rows of the current PauliTable that anti-commute with all Pauli’s in other. If no rows satisfy the condition the returned array will be empty.
Parameters
other (PauliTable) – a single Pauli or multi-row PauliTable.
Returns
index array of the anti-commuting rows.
Return type
array
argsort
StabilizerTable.argsort(weight=False)
Return indices for sorting the rows of the PauliTable.
The default sort method is lexicographic sorting of Paulis by qubit number. By using the weight kwarg the output can additionally be sorted by the number of non-identity terms in the Stabilizer, where the set of all Pauli’s of a given weight are still ordered lexicographically.
This does not sort based on phase values. It will preserve the original order of rows with the same Pauli’s but different phases.
Parameters
weight (bool) – optionally sort by weight if True (Default: False).
Returns
the indices for sorting the table.
Return type
array
commutes
StabilizerTable.commutes(pauli)
Return list of commutation properties for each row with a Pauli.
The returned vector is the same length as the size of the table and contains True for rows that commute with the Pauli, and False for the rows that anti-commute.
Parameters
pauli (PauliTable) – a single Pauli row.
Returns
The boolean vector of which rows commute or anti-commute.
Return type
array
Raises
QiskitError – if input is not a single Pauli row.
commutes_with_all
StabilizerTable.commutes_with_all(other)
Return indexes of rows that commute other.
If other is a multi-row Pauli table the returned vector indexes rows of the current PauliTable that commute with all Pauli’s in other. If no rows satisfy the condition the returned array will be empty.
Parameters
other (PauliTable) – a single Pauli or multi-row PauliTable.
Returns
index array of the commuting rows.
Return type
array
compose
StabilizerTable.compose(other, qargs=None, front=False)
Return the compose output product of two tables.
This returns the combination of the compose product of all stabilizers in the current table with all stabilizers in the other table.
The individual stabilizer compose product is given by
A.compose(B) | I | X | Y | Z |
---|
| I | I | X | Y | Z | | X | X | I | Z | -Y | | Y | Y | -Z | -I | X | | Z | Z | Y | -X | I |
If front=True the composition will be given by the dot()
method.
Example
from qiskit.quantum_info.operators import StabilizerTable
current = StabilizerTable.from_labels(['+I', '-X'])
other = StabilizerTable.from_labels(['+X', '-Z'])
print(current.compose(other))
StabilizerTable: ['+X', '-Z', '-I', '-Y']
Parameters
- other (StabilizerTable) – another StabilizerTable.
- qargs (None or list) – qubits to apply compose product on (Default: None).
- front (bool) – If True use dot composition method (default: False).
Returns
the compose outer product table.
Return type
Raises
QiskitError – if other cannot be converted to a StabilizerTable.
conjugate
StabilizerTable.conjugate()
Not implemented.
copy
StabilizerTable.copy()
Return a copy of the StabilizerTable.
delete
StabilizerTable.delete(ind, qubit=False)
Return a copy with Stabilizer rows deleted from table.
When deleting qubit columns, qubit-0 is the right-most (largest index) column, and qubit-(N-1) is the left-most (0 index) column of the underlying X
and Z
arrays.
Parameters
- ind (int or list) – index(es) to delete.
- qubit (bool) – if True delete qubit columns, otherwise delete Stabilizer rows (Default: False).
Returns
the resulting table with the entries removed.
Return type
Raises
QiskitError – if ind is out of bounds for the array size or number of qubits.
dot
StabilizerTable.dot(other, qargs=None)
Return the dot output product of two tables.
This returns the combination of the compose product of all stabilizers in the current table with all stabilizers in the other table.
The individual stabilizer dot product is given by
A.dot(B) | I | X | Y | Z |
---|
| I | I | X | Y | Z | | X | X | I | -Z | Y | | Y | Y | Z | -I | -X | | Z | Z | -Y | X | I |
Example
from qiskit.quantum_info.operators import StabilizerTable
current = StabilizerTable.from_labels(['+I', '-X'])
other = StabilizerTable.from_labels(['+X', '-Z'])
print(current.dot(other))
StabilizerTable: ['+X', '-Z', '-I', '+Y']
Parameters
- other (StabilizerTable) – another StabilizerTable.
- qargs (None or list) – qubits to apply dot product on (Default: None).
Returns
the dot outer product table.
Return type
Raises
QiskitError – if other cannot be converted to a StabilizerTable.
expand
StabilizerTable.expand(other)
Return the expand output product of two tables.
This returns the combination of the tensor product of all stabilizers in the other table with all stabilizers in the current table. The current tables qubits will be the least-significant in the returned table. This is the opposite tensor order to tensor()
.
Example
from qiskit.quantum_info.operators import StabilizerTable
current = StabilizerTable.from_labels(['+I', '-X'])
other = StabilizerTable.from_labels(['-Y', '+Z'])
print(current.expand(other))
StabilizerTable: ['-YI', '+YX', '+ZI', '-ZX']
Parameters
other (StabilizerTable) – another StabilizerTable.
Returns
the expand outer product table.
Return type
Raises
QiskitError – if other cannot be converted to a StabilizerTable.
from_labels
classmethod StabilizerTable.from_labels(labels)
Construct a StabilizerTable from a list of Pauli stabilizer strings.
Pauli Stabilizer string labels are Pauli strings with an optional "+"
or "-"
character. If there is no +/-sign a + phase is used by default.
Label | Phase | Symplectic | Matrix | Pauli |
---|
| "+I"
| 0 | | | |
| "-I"
| 1 | | | |
| "X"
| 0 | | | |
| "-X"
| 1 | | | |
| "Y"
| 0 | | | |
| "-Y"
| 1 | | | |
| "Z"
| 0 | | | |
| "-Z"
| 1 | | | |
Parameters
labels (list) – Pauli stabilizer string label(es).
Returns
the constructed StabilizerTable.
Return type
Raises
QiskitError – If the input list is empty or contains invalid Pauli stabilizer strings.
input_dims
StabilizerTable.input_dims(qargs=None)
Return tuple of input dimension for specified subsystems.
insert
StabilizerTable.insert(ind, value, qubit=False)
Insert stabilizers’s into the table.
When inserting qubit columns, qubit-0 is the right-most (largest index) column, and qubit-(N-1) is the left-most (0 index) column of the underlying X
and Z
arrays.
Parameters
- ind (int) – index to insert at.
- value (StabilizerTable) – values to insert.
- qubit (bool) – if True delete qubit columns, otherwise delete Pauli rows (Default: False).
Returns
the resulting table with the entries inserted.
Return type
Raises
QiskitError – if the insertion index is invalid.
label_iter
StabilizerTable.label_iter()
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.
Returns
label iterator object for the StabilizerTable.
Return type
LabelIterator
matrix_iter
StabilizerTable.matrix_iter(sparse=False)
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.
Parameters
sparse (bool) – optionally return sparse CSR matrices if True, otherwise return Numpy array matrices (Default: False)
Returns
matrix iterator object for the StabilizerTable.
Return type
MatrixIterator
output_dims
StabilizerTable.output_dims(qargs=None)
Return tuple of output dimension for specified subsystems.
power
StabilizerTable.power(n)
Return the compose of a operator with itself n times.
Parameters
n (int) – the number of times to compose with self (n>0).
Returns
the n-times composed operator.
Return type
Raises
QiskitError – if the input and output dimensions of the operator are not equal, or the power is not a positive integer.
reshape
StabilizerTable.reshape(input_dims=None, output_dims=None, num_qubits=None)
Return a shallow copy with reshaped input and output subsystem dimensions.
Parameters
- 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].
Returns
returns self with reshaped input and output dimensions.
Return type
BaseOperator
Raises
QiskitError – if combined size of all subsystem input dimension or subsystem output dimensions is not constant.
sort
StabilizerTable.sort(weight=False)
Sort 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 Pauli’s of a given weight are still ordered lexicographically.
This does not sort based on phase values. It will preserve the original order of rows with the same Pauli’s but different phases.
Consider sorting all a random ordering of all 2-qubit Paulis
from numpy.random import shuffle
from qiskit.quantum_info.operators import StabilizerTable
# 2-qubit labels
labels = ['+II', '+IX', '+IY', '+IZ', '+XI', '+XX', '+XY', '+XZ',
'+YI', '+YX', '+YY', '+YZ', '+ZI', '+ZX', '+ZY', '+ZZ',
'-II', '-IX', '-IY', '-IZ', '-XI', '-XX', '-XY', '-XZ',
'-YI', '-YX', '-YY', '-YZ', '-ZI', '-ZX', '-ZY', '-ZZ']
# Shuffle Labels
shuffle(labels)
st = StabilizerTable.from_labels(labels)
print('Initial Ordering')
print(st)
# Lexicographic Ordering
srt = st.sort()
print('Lexicographically sorted')
print(srt)
# Weight Ordering
srt = st.sort(weight=True)
print('Weight sorted')
print(srt)
Initial Ordering
StabilizerTable: ['-ZY', '-YY', '+ZX', '+II', '-IX', '-ZZ', '+YX', '+XI', '+YY', '-XY', '+IZ', '-ZI', '+XZ', '-YZ', '+ZY', '-XX', '+YI', '-II', '+IY', '-YX', '-XZ', '+IX', '-IY', '+ZZ', '-XI', '-IZ', '-YI', '+XX', '+XY', '-ZX', '+YZ', '+ZI']
Lexicographically sorted
StabilizerTable: ['+II', '-II', '-IX', '+IX', '+IY', '-IY', '+IZ', '-IZ', '+XI', '-XI', '-XX', '+XX', '-XY', '+XY', '+XZ', '-XZ', '+YI', '-YI', '+YX', '-YX', '-YY', '+YY', '-YZ', '+YZ', '-ZI', '+ZI', '+ZX', '-ZX', '-ZY', '+ZY', '-ZZ', '+ZZ']
Weight sorted
StabilizerTable: ['+II', '-II', '-IX', '+IX', '+IY', '-IY', '+IZ', '-IZ', '+XI', '-XI', '+YI', '-YI', '-ZI', '+ZI', '-XX', '+XX', '-XY', '+XY', '+XZ', '-XZ', '+YX', '-YX', '-YY', '+YY', '-YZ', '+YZ', '+ZX', '-ZX', '-ZY', '+ZY', '-ZZ', '+ZZ']
Parameters
weight (bool) – optionally sort by weight if True (Default: False).
Returns
a sorted copy of the original table.
Return type
tensor
StabilizerTable.tensor(other)
Return the tensor output product of two tables.
This returns the combination of the tensor product of all stabilizers in the current table with all stabilizers in the other table. The other tables qubits will be the least-significant in the returned table. This is the opposite tensor order to tensor()
.
Example
from qiskit.quantum_info.operators import StabilizerTable
current = StabilizerTable.from_labels(['+I', '-X'])
other = StabilizerTable.from_labels(['-Y', '+Z'])
print(current.tensor(other))
StabilizerTable: ['-IY', '+IZ', '+XY', '-XZ']
Parameters
other (StabilizerTable) – another StabilizerTable.
Returns
the tensor outer product table.
Return type
Raises
QiskitError – if other cannot be converted to a StabilizerTable.
to_labels
StabilizerTable.to_labels(array=False)
Convert a StabilizerTable to a list Pauli stabilizer string labels.
For large StabilizerTables converting using the array=True
kwarg will be more efficient since it allocates memory for the full Numpy array of labels in advance.
Label | Phase | Symplectic | Matrix | Pauli |
---|
| "+I"
| 0 | | | |
| "-I"
| 1 | | | |
| "X"
| 0 | | | |
| "-X"
| 1 | | | |
| "Y"
| 0 | | | |
| "-Y"
| 1 | | | |
| "Z"
| 0 | | | |
| "-Z"
| 1 | | | |
Parameters
array (bool) – return a Numpy array if True, otherwise return a list (Default: False).
Returns
The rows of the StabilizerTable in label form.
Return type
list or array
to_matrix
StabilizerTable.to_matrix(sparse=False, array=False)
Convert to a list or array of Stabilizer matrices.
For large StabilizerTables converting using the array=True
kwarg will be more efficient since it allocates memory for the full rank-3 Numpy array of matrices in advance.
Label | Phase | Symplectic | Matrix | Pauli |
---|
| "+I"
| 0 | | | |
| "-I"
| 1 | | | |
| "X"
| 0 | | | |
| "-X"
| 1 | | | |
| "Y"
| 0 | | | |
| "-Y"
| 1 | | | |
| "Z"
| 0 | | | |
| "-Z"
| 1 | | | |
Parameters
- 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).
Returns
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.
Return type
list
transpose
StabilizerTable.transpose()
Not implemented.
unique
StabilizerTable.unique(return_index=False, return_counts=False)
Return unique stabilizers from the table.
Example
from qiskit.quantum_info.operators import StabilizerTable
st = StabilizerTable.from_labels(['+X', '+I', '-I', '-X', '+X', '-X', '+I'])
unique = st.unique()
print(unique)
StabilizerTable: ['+X', '+I', '-I', '-X']
Parameters
- 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.
Returns
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.
Return type
Attributes
X
The X block of the array
.
Z
The Z block of the array
.
array
The underlying boolean array.
dim
Return tuple (input_shape, output_shape).
num_qubits
Return the number of qubits if a N-qubit operator or None otherwise.
pauli
Return PauliTable
phase
Return phase vector
qargs
Return the qargs for the operator.
settings
Return settings.
Return type
Dict
shape
The full shape of the array()
size
The number of Pauli rows in the table.