qiskit.aqua.operators.legacy.MatrixOperator

class MatrixOperator(matrix, basis=None, z2_symmetries=None, atol=1e-12, name=None)

Operators relevant for quantum applications

Note

For grouped paulis representation, all operations will always convert it to paulis and then convert it back. (It might be a performance issue.)

Parameters

• matrix (numpy.ndarray or scipy.sparse.csr_matrix) – a 2-D sparse matrix represents operator (using CSR format internally)

• basis (list[tuple(object, [int])], optional) – the grouping basis, each element is a tuple composed of the basis and the indices to paulis which are belonged 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 (Z2Symmetries) – represent the Z2 symmetries

• atol (float) – atol

• name (str) – name

__init__(matrix, basis=None, z2_symmetries=None, atol=1e-12, name=None)

Parameters

• matrix (numpy.ndarray or scipy.sparse.csr_matrix) – a 2-D sparse matrix represents operator (using CSR format internally)

• basis (list[tuple(object, [int])], optional) – the grouping basis, each element is a tuple composed of the basis and the indices to paulis which are belonged 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 (Z2Symmetries) – represent the Z2 symmetries

• atol (float) – atol

• name (str) – name

Methods

__init__(matrix[, basis, z2_symmetries, …])	param matrix a 2-D sparse matrix represents operator (using CSR format internally)
add(other[, copy])
chop([threshold, copy])	Eliminate the real and imagine part of coeff in each pauli by threshold.
construct_evaluation_circuit(wave_function)	Construct the circuits for evaluation.
copy()	Get a copy of self.
evaluate_with_result(result[, …])	Use the executed result with operator to get the evaluated value.
evaluate_with_statevector(quantum_state)	param quantum_state quantum state
evolve(state_in[, evo_time, …])	Carry out the eoh evolution for the operator under supplied specifications.
is_empty()	Check Operator is empty or not.
print_details()	returns a formatted operator.
sub(other[, copy])
to_opflow()	to op flow

Attributes

atol	return atol
basis	returns basis
dense_matrix	Getter of matrix in dense matrix form.
dia_matrix	diagonal matrix
matrix	Getter of matrix.
name	returns name
num_qubits	number of qubits required for the operator.
z2_symmetries	returns z2 symmetries

add(other, copy=False)

property atol

return atol

property basis

returns basis

chop(threshold=None, copy=False)

Eliminate the real and imagine part of coeff in each pauli by threshold. If pauli’s coeff is less then threshold in both real and imagine parts, the pauli is removed. To align the internal representations, all available representations are chopped. The chopped result is stored back to original property. Note: if coeff is real-only, the imag part is skipped.

Parameters

• threshold (float) – threshold chops the paulis

• copy (bool) – copy or self

Returns

self or copy

Return type

MatrixOperator

construct_evaluation_circuit(wave_function, statevector_mode=True, use_simulator_snapshot_mode=None, circuit_name_prefix='')

Construct the circuits for evaluation.

Parameters

• wave_function (QuantumCircuit) – the quantum circuit.

• statevector_mode (bool) – mode

• use_simulator_snapshot_mode (bool) – uses simulator operator mode

• circuit_name_prefix (str, optional) – a prefix of circuit name

Returns

the circuits for computing the expectation of the operator over

the wavefunction evaluation.

Return type

list[QuantumCircuit]

copy()

Get a copy of self.

property dense_matrix

Getter of matrix in dense matrix form.

property dia_matrix

diagonal matrix

evaluate_with_result(result, statevector_mode=True, use_simulator_snapshot_mode=None, circuit_name_prefix='')

Use the executed result with operator to get the evaluated value.

Parameters

• result (qiskit.Result) – the result from the backend

• statevector_mode (bool) – mode

• use_simulator_snapshot_mode (bool) – uses simulator operator mode

• circuit_name_prefix (str, optional) – a prefix of circuit name

Returns

the mean value float: the standard deviation

Return type

float

Raises

AquaError – if Operator is empty

evaluate_with_statevector(quantum_state)

Parameters

quantum_state (numpy.ndarray) – quantum state

Returns

the mean value float: the standard deviation

Return type

float

Raises

AquaError – if Operator is empty

evolve(state_in, evo_time=0, num_time_slices=0, expansion_mode='trotter', expansion_order=1)

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

Parameters

• state_in (Union(list,numpy.array)) – A vector representing the initial state for the evolution

• evo_time (Union(complex, float)) – 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

Returns

Return the matrix vector multiplication result.

Return type

numpy.array

Raises

• ValueError – Invalid arguments

• AquaError – if Operator is empty

is_empty()

Check Operator is empty or not.

Returns

is empty?

Return type

bool

property matrix

Getter of matrix.

property name

returns name

property num_qubits

number of qubits required for the operator.

Returns

number of qubits

Return type

int

print_details()

Returns

a formatted operator.

Return type

str

sub(other, copy=False)

to_opflow()

to op flow

property z2_symmetries

returns z2 symmetries