squlearn.encoding_circuit.QiskitEncodingCircuit

class squlearn.encoding_circuit.QiskitEncodingCircuit(qiskit_circuit: BlueprintCircuit | Callable | QuantumCircuit, mode: str = 'auto', decompose: bool = False, feature_label: str = 'x', parameter_label: str = 'θp', **kwargs)

Wrapper to create sQUlearn encoding circuits from the Qiskit circuit library.

Example: create a encoding circuit from Qiskit TwoLocal map

from squlearn.encoding_circuit import QiskitEncodingCircuit
from qiskit.circuit.library import TwoLocal
local = TwoLocal(3, 'ry', 'cx', 'linear', reps=2, insert_barriers=True)
QiskitEncodingCircuit(local).draw("mpl")

An alternative call can be made by passing the circuit library function and its arguments:

from squlearn.encoding_circuit import QiskitEncodingCircuit
from qiskit.circuit.library import ZZFeatureMap
QiskitEncodingCircuit(ZZFeatureMap,feature_dimension=4).draw("mpl")

Parameters:

• qiskit_circuit (Union[BlueprintCircuit, Callable,QuantumCircuit]) – A Qiskit circuit or a Qiskit circuit library function

• mode (str) – Option for considering the circuit parameters as features or trainable parameters. Can be features or parameters or auto. With auto, the mode is automatically determined depending on the parameter name. (default: auto)

• decompose (bool) – If True, the decompose method is called on the inputted circuit object. (default: True)

• feature_label (str) – The label of the parameters that are considered as features. (default: x)

• parameter_label (str) – The label of the parameters that are considered as trainable parameters. (default: θp)

• **kwargs – Arguments for the Qiskit circuit library function if it is passed as a callable

compose(x, concatenate_features=True, concatenate_parameters=False)

Composition of encoding circuits with options for handling features and parameters

Number of qubits and features have to be equal in both encoding circuits! The special function and properties of the both encoding circuits are lost by this composition.

Parameters:

• self (EncodingCircuitBase) – right / first encoding circuit

• x (EncodingCircuitBase) – left / second encoding circuit

Returns:

Returns the composed encoding circuit as special class ComposedEncodingCircuit

draw(output: str = None, feature_label: str = 'x', parameter_label: str = 'p', decompose: bool = False, **kwargs) → None

Draws the encoding circuit circuit using the QuantumCircuit.draw() function.

Parameters:

• feature_label (str) – Label for the feature vector (default:”x”).

• parameter_label (str) – Label for the parameter vector (default:”p”).

• decompose (bool) – If True, the circuit is decomposed before printing (default: False).

• kwargs – Additional arguments from Qiskit’s QuantumCircuit.draw() function.

Returns:

Returns the circuit in qiskit QuantumCircuit.draw() format

generate_initial_parameters(seed: int | None = None) → ndarray

Generates random parameters for the encoding circuit

Parameters:

seed (Union[int,None]) – Seed for the random number generator (default: None)

Returns:

The randomly generated parameters

get_circuit(features: ParameterVector | ndarray, parameters: ParameterVector | ndarray) → QuantumCircuit

Returns the circuit of the Qiskit Encoding Circuit

Parameters:

• features (Union[ParameterVector,np.ndarray]) – Input vector of the features from which the gate inputs are obtained.

• param_vec (Union[ParameterVector,np.ndarray]) – Input vector of the parameters from which the gate inputs are obtained.

Returns:

The circuit of the Qiskit Encoding Circuit with the assigned parameters.

get_params(deep: bool = True) → dict

Returns hyper-parameters and their values of the Qiskit encoding circuit

No hyper-parameters are available for the Qiskit encoding circuit!

Parameters:

deep (bool) – If True, also the parameters for contained objects are returned (default=True).

Returns:

Dictionary with hyper-parameters and values.

inverse()

Returns the inverse of the encoding circuit.

Returns:

The inverse of the encoding circuit

set_params(**params) → EncodingCircuitBase

Sets value of the encoding circuit hyper-parameters.

Parameters:

params – Hyper-parameters and their values, e.g. num_qubits=2.