qiskit.aqua.operators.legacy.WeightedPauliOperator¶

class WeightedPauliOperator(paulis, basis=None, z2_symmetries=None, atol=1e-12, name=None)[Quellcode]¶

Weighted Pauli Operator

Parameter

paulis (List[List[Union[complex, Pauli]]]) – the list of weighted Paulis, where a weighted pauli is composed of a length-2 list and the first item is the weight and the second item is the Pauli object.
basis (Optional[List[Tuple[object, List[int]]]]) – the grouping basis, each element is a tuple composed of the basis and the indices to paulis which belong to that group. e.g., if tpb basis is used, the object will be a pauli. By default, the group is equal to non-grouping, each pauli is its own basis.
z2_symmetries (Optional[Z2Symmetries]) – recording the z2 symmetries info
atol (float) – the threshold used in truncating paulis
name (Optional[str]) – the name of operator.

__init__(paulis, basis=None, z2_symmetries=None, atol=1e-12, name=None)[Quellcode]¶

Parameter

paulis (List[List[Union[complex, Pauli]]]) – the list of weighted Paulis, where a weighted pauli is composed of a length-2 list and the first item is the weight and the second item is the Pauli object.
basis (Optional[List[Tuple[object, List[int]]]]) – the grouping basis, each element is a tuple composed of the basis and the indices to paulis which belong to that group. e.g., if tpb basis is used, the object will be a pauli. By default, the group is equal to non-grouping, each pauli is its own basis.
z2_symmetries (Optional[Z2Symmetries]) – recording the z2 symmetries info
atol (float) – the threshold used in truncating paulis
name (Optional[str]) – the name of operator.

Methods

`__init__`(paulis[, basis, z2_symmetries, …])	type paulis `List`[`List`[`Union`[`complex`, `Pauli`]]]
`add`(other[, copy])	Perform self + other.
`anticommute_with`(other)	Anti commutes with
`chop`([threshold, copy])	Eliminate the real and imagine part of weight in each pauli by threshold.
`commute_with`(other)	Commutes with
`construct_evaluation_circuit`(wave_function, …)	Construct the circuits for evaluation, which calculating the expectation <psi\|H\|psi>.
`copy`()	Get a copy of self
`evaluate_with_result`(result, statevector_mode)	This method can be only used with the circuits generated by the `construct_evaluation_circuit()` method with the same circuit_name_prefix name since the circuit names are tied to some meanings.
`evaluate_with_statevector`(quantum_state)	param quantum_state a quantum state.
`evaluation_instruction`(statevector_mode[, …])	param statevector_mode will it be run on statevector simulator or not
`evolve`([state_in, evo_time, …])	Carry out the eoh evolution for the operator under supplied specifications.
`evolve_instruction`([evo_time, …])	Carry out the eoh evolution for the operator under supplied specifications.
`from_dict`(dictionary[, before_04])	Load paulis from a dictionary to construct an Operator.
`from_file`(file_name[, before_04])	Load paulis in a file to construct an Operator.
`from_list`(paulis[, weights, name])	Create a WeightedPauliOperator via a pair of list.
`is_empty`()	Check Operator is empty or not.
`multiply`(other)	Perform self * other, and the phases are tracked.
`print_details`()	Print out the operator in details.
`reorder_paulis`()	Reorder the paulis based on the basis and return the reordered paulis.
`rounding`(decimals[, copy])	Rounding the weight.
`simplify`([copy])	Merge the paulis whose bases are identical and the pauli with zero coefficient would be removed.
`sub`(other[, copy])	Perform self - other.
`to_dict`()	Save operator to a dict in pauli representation.
`to_file`(file_name)	Save operator to a file in pauli representation.
`to_opflow`([reverse_endianness])	to op flow

Attributes

`atol`	get atol
`basis`	returns basis
`name`	returns name
`num_qubits`	Number of qubits required for the operator.
`paulis`	get paulis
`z2_symmetries`	returns z2 symmetries

add(other, copy=False)[Quellcode]¶

Perform self + other.

Parameter

other (WeightedPauliOperator) – to-be-combined operator
copy (bool) – working on a copy or self, if False, the results are written back to self.

Rückgabe

operator

Rückgabetyp

WeightedPauliOperator

anticommute_with(other)[Quellcode]¶: Anti commutes with

property atol¶: get atol

property basis¶: returns basis

chop(threshold=None, copy=False)[Quellcode]¶

Eliminate the real and imagine part of weight in each pauli by threshold. If pauli’s weight is less then threshold in both real and imaginary parts, the pauli is removed.

Bemerkung

If weight is real-only, the imaginary part is skipped.

Parameter

threshold (float) – the threshold is used to remove the paulis
copy (bool) – chop on a copy or self

Rückgabe

if copy is True, the original operator is unchanged; otherwise,: the operator is mutated.

Rückgabetyp

WeightedPauliOperator

commute_with(other)[Quellcode]¶: Commutes with

construct_evaluation_circuit(wave_function, statevector_mode, qr=None, cr=None, use_simulator_snapshot_mode=False, circuit_name_prefix='')[Quellcode]¶

Construct the circuits for evaluation, which calculating the expectation <psi|H|psi>.

At statevector mode: to simplify the computation, we do not build the whole circuit for <psi|H|psi>, instead of that we construct an individual circuit <psi|, and a bundle circuit for H|psi>

Parameter

wave_function (QuantumCircuit) – the quantum circuit.
statevector_mode (bool) – indicate which type of simulator are going to use.
qr (QuantumRegister, optional) – the quantum register associated with the input_circuit
cr (ClassicalRegister, optional) – the classical register associated with the input_circuit
use_simulator_snapshot_mode (bool, optional) – if aer_provider is used, we can do faster evaluation for pauli mode on statevector simulation
circuit_name_prefix (str, optional) – a prefix of circuit name

Rückgabe

a list of quantum circuits and each circuit with a unique name:: circuit_name_prefix + Pauli string

Rückgabetyp

list[QuantumCircuit]

Verursacht

AquaError – if Operator is empty
AquaError – if quantum register is not provided explicitly and cannot find quantum register with q as the name
AquaError – The provided qr is not in the wave_function

copy()[Quellcode]¶: Get a copy of self

evaluate_with_result(result, statevector_mode, use_simulator_snapshot_mode=False, circuit_name_prefix='')[Quellcode]¶

This method can be only used with the circuits generated by the construct_evaluation_circuit() method with the same circuit_name_prefix name since the circuit names are tied to some meanings.

Calculate the evaluated value with the measurement results.

Parameter

result (qiskit.Result) – the result from the backend.
statevector_mode (bool) – indicate which type of simulator are used.
use_simulator_snapshot_mode (bool) – if aer_provider is used, we can do faster evaluation for pauli mode on statevector simulation
circuit_name_prefix (str) – a prefix of circuit name

Rückgabe

the mean value float: the standard deviation

Rückgabetyp

float

Verursacht

AquaError – if Operator is empty

evaluate_with_statevector(quantum_state)[Quellcode]¶

Parameter: quantum_state (numpy.ndarray) – a quantum state.
Rückgabe: the mean value float: the standard deviation
Rückgabetyp: float
Verursacht: AquaError – if Operator is empty

evaluation_instruction(statevector_mode, use_simulator_snapshot_mode=False)[Quellcode]¶

Parameter

statevector_mode (bool) – will it be run on statevector simulator or not
use_simulator_snapshot_mode (bool) – will it use qiskit aer simulator operator mode

Rückgabe

Pauli-instruction pair.

Rückgabetyp

dict

Verursacht

AquaError – if Operator is empty
MissingOptionalLibraryError – qiskit-aer not installed

evolve(state_in=None, evo_time=0, num_time_slices=1, quantum_registers=None, expansion_mode='trotter', expansion_order=1)[Quellcode]¶

Carry out the eoh evolution for the operator under supplied specifications.

Parameter

state_in (QuantumCircuit) – a circuit describes the input state
evo_time (Union(complex, float, Parameter, ParameterExpression)) – The evolution time
num_time_slices (int) – The number of time slices for the expansion
quantum_registers (QuantumRegister) – The QuantumRegister to build the QuantumCircuit off of
expansion_mode (str) – The mode under which the expansion is to be done. Currently support ‚trotter‘, which follows the expansion as discussed in http://science.sciencemag.org/content/273/5278/1073, and ‚suzuki‘, which corresponds to the discussion in https://arxiv.org/pdf/quant-ph/0508139.pdf
expansion_order (int) – The order for suzuki expansion

Rückgabe

The constructed circuit.

Rückgabetyp

QuantumCircuit

Verursacht

AquaError – quantum_registers must be in the provided state_in circuit
AquaError – if operator is empty

evolve_instruction(evo_time=0, num_time_slices=1, expansion_mode='trotter', expansion_order=1)[Quellcode]¶

Carry out the eoh evolution for the operator under supplied specifications.

Parameter

evo_time (Union(complex, float, Parameter, ParameterExpression)) – The evolution time
num_time_slices (int) – The number of time slices for the expansion
expansion_mode (str) – The mode under which the expansion is to be done. Currently support ‚trotter‘, which follows the expansion as discussed in http://science.sciencemag.org/content/273/5278/1073, and ‚suzuki‘, which corresponds to the discussion in https://arxiv.org/pdf/quant-ph/0508139.pdf
expansion_order (int) – The order for suzuki expansion

Rückgabe

The constructed QuantumCircuit.

Rückgabetyp

QuantumCircuit

Verursacht

ValueError – Number of time slices should be a non-negative integer
NotImplementedError – expansion mode not supported
AquaError – if operator is empty

classmethod from_dict(dictionary, before_04=False)[Quellcode]¶

Load paulis from a dictionary to construct an Operator. The dictionary must comprise the key ‚paulis‘ having a value which is an array of pauli dicts. Each dict in this array must be represented by label and coeff (real and imag) such as in the following example:

{'paulis':
    [
        {'label': 'IIII',
         'coeff': {'real': -0.33562957575267038, 'imag': 0.0}},
        {'label': 'ZIII',
         'coeff': {'real': 0.28220597164664896, 'imag': 0.0}},
         ...
    ]
 }

Parameter

dictionary (dict) – dictionary, which contains a list of Paulis and coefficients.
before_04 (bool) – support the format before Aqua 0.4.

Rückgabe

the operator created from the input dictionary.

Rückgabetyp

WeightedPauliOperator

Verursacht

AquaError – Invalid dictionary

classmethod from_file(file_name, before_04=False)[Quellcode]¶

Load paulis in a file to construct an Operator.

Parameter

file_name (str) – path to the file, which contains a list of Paulis and coefficients.
before_04 (bool) – support the format before Aqua 0.4.

Rückgabe

the loaded operator.

Rückgabetyp

WeightedPauliOperator

classmethod from_list(paulis, weights=None, name=None)[Quellcode]¶

Create a WeightedPauliOperator via a pair of list.

Parameter

paulis (list[Pauli]) – the list of Paulis
weights (list[complex], optional) – the list of weights, if it is None, all weights are 1.
name (str, optional) – name of the operator.

Rückgabe

operator

Rückgabetyp

WeightedPauliOperator

Verursacht

ValueError – The length of weights and paulis must be the same

is_empty()[Quellcode]¶

Check Operator is empty or not.

Rückgabe: True if empty, False otherwise
Rückgabetyp: bool

multiply(other)[Quellcode]¶

Perform self * other, and the phases are tracked.

Parameter: other (WeightedPauliOperator) – an operator
Rückgabe: the multiplied operator
Rückgabetyp: WeightedPauliOperator

property name¶: returns name

property num_qubits¶

Number of qubits required for the operator.

Rückgabe: number of qubits
Rückgabetyp: int

property paulis¶: get paulis

print_details()[Quellcode]¶

Print out the operator in details.

Rückgabe: a formatted string describes the operator.
Rückgabetyp: str

reorder_paulis()[Quellcode]¶

Reorder the paulis based on the basis and return the reordered paulis.

Rückgabetyp: List[List[Union[complex, Pauli]]]
Rückgabe: the ordered paulis based on the basis.

rounding(decimals, copy=False)[Quellcode]¶

Rounding the weight.

Parameter

decimals (int) – rounding the weight to the decimals.
copy (bool) – chop on a copy or self

Rückgabe

operator

Rückgabetyp

WeightedPauliOperator

simplify(copy=False)[Quellcode]¶

Merge the paulis whose bases are identical and the pauli with zero coefficient would be removed.

Bemerkung

This behavior of this method is slightly changed, it will remove the paulis whose weights are zero.

Parameter: copy (bool) – simplify on a copy or self
Rückgabe: the simplified operator
Rückgabetyp: WeightedPauliOperator

sub(other, copy=False)[Quellcode]¶

Perform self - other.

Parameter

other (WeightedPauliOperator) – to-be-combined operator
copy (bool) – working on a copy or self, if False, the results are written back to self.

Rückgabe

operator

Rückgabetyp

WeightedPauliOperator

to_dict()[Quellcode]¶

Save operator to a dict in pauli representation.

Rückgabe: a dictionary contains an operator with pauli representation.
Rückgabetyp: dict

to_file(file_name)[Quellcode]¶

Save operator to a file in pauli representation.

Parameter: file_name (str) – path to the file

to_opflow(reverse_endianness=False)[Quellcode]¶: to op flow

property z2_symmetries¶: returns z2 symmetries