squlearn.util.qulacs.QulacsCircuit

class squlearn.util.qulacs.QulacsCircuit(circuit: QuantumCircuit, observable: None | SparsePauliOp | List[SparsePauliOp] | str = None)

Class for converting a Qiskit circuit to a Qulacs circuit.

Parameters:

• circuit (QiskitQuantumCircuit) – Qiskit circuit to convert to Qulacs

• observable (Union[None, SparsePauliOp, List[SparsePauliOp]]) – Observable to be measured, if None, no observable is defined.

Attributes:

num_qubits

Number of qubits in the circuit

Type:

int

circuit_parameter_names

List of circuit parameter names

Type:

list

observable_parameter_names

List of observable parameter names

Type:

list

argument_names

List of all circuit and observable parameters names

Type:

list

hash

Hashable object of the circuit and observable for caching

Type:

str

Methods:

build_observable_instructions(observables: List[SparsePauliOp] | SparsePauliOp)

Function to build the instructions for the Qulacs observable from the Qiskit observable.

This functions converts the Qiskit SparsePauli and parameter expressions to Qulacs compatible Pauli words and functions.

Parameters:

observable (Union[List[SparsePauliOp], SparsePauliOp]) – Qiskit observable to convert to Qulacs

Returns:

Tuple with lists of Qulacs observable parameter functions, Qulacs Pauli words, Qulacs observable parameters and Qulacs observable parameter dimensions

get_circuit_func(gradient_param: None | ParameterVectorElement | List[ParameterVectorElement] = None) → callable

Returns the function for the creating the qulacs circuit and its gradients.

Parameters:

gradient_param (Union[None, ParameterVectorElement, List[ParameterVectorElement]]) – Parameters to calculate the gradient for

get_observable_func()

Returns a function for creating the qulacs observable depending on the parameters.

get_observables_for_gradient(gradient_parameters: None | ParameterVectorElement | List[ParameterVectorElement] = None) → callable

Returns the Qulacs observable function for the observable depending on parameters.

Parameters:

gradient_parameters (Union[None, ParameterVectorElement, List[ParameterVectorElement]]) – Parameters to calculate the gradient for

Returns:

Function that returns the Qulacs observable for the given parameters

Return type:

callable

get_outer_jacobian_circuit(gradient_parameters: None | ParameterVectorElement | List[ParameterVectorElement] = None) → callable

Returns the outer jacobian needed for the chain rule in circuit derivatives.

Qulacs does not support multiple parameters and parameter expressions, so we need to calculate a transformation which also includes the gradient of the parameter expression.

Parameters:

gradient_parameters (Union[None, ParameterVectorElement, List[ParameterVectorElement]]) – Parameters to calculate the gradient for

Returns:

Function that calculates the outer jacobian for given parameters values

Return type:

callable

get_outer_jacobian_observables(gradient_parameters: None | ParameterVectorElement | List[ParameterVectorElement] = None) → callable

Returns the outer jacobian needed for the chain rule in circuit derivatives.

Qulacs does not support multiple parameters and parameter expressions, so we need to calculate a transformation which also includes the gradient of the parameter expression.

Parameters:

gradient_parameters (Union[None, ParameterVectorElement, List[ParameterVectorElement]]) – Parameters to calculate the gradient for

Returns:

Function that calculates the outer jacobian for the observable parameters

Return type:

callable