Objective function(s)

class MaximizeStateFidelity(target, ansatz, settings)

Bases: object

Simplest possible objective function for use with AQC-Tensor.

Its definition is given by Eq. (7) in arXiv:2301.08609v6:

Minimizing this function is equivalent to maximizing the pure-state fidelity between the state prepared by the ansatz circuit at the current parameter point, $V(\vec\theta) |0\rangle$, and the target state, $| \psi_\mathrm{target} \rangle$.

When called with an ndarray of parameters, this object will return (objective_value, gradient) as a tuple[float, numpy.ndarray].

Initialize the objective function.

Parameters

• ansatz (QuantumCircuit) – Parametrized ansatz circuit.
• target (TensorNetworkState) – Target state in tensor-network representation.
• settings (TensorNetworkSimulationSettings) – Tensor network simulation settings.

loss_function

target

class OneMinusFidelity(target, ansatz, settings)

Bases: MaximizeStateFidelity

DEPRECATED objective function, equivalent to MaximizeStateFidelity.

Initialize the objective function.

The OneMinusFidelity class is DEPRECATED since v0.2. Please migrate to MaximizeStateFidelity as soon as possible.

Parameters

• ansatz (QuantumCircuit) – Parametrized ansatz circuit.
• target (TensorNetworkState) – Target state in tensor-network representation.
• settings (TensorNetworkSimulationSettings) – Tensor network simulation settings.

__call__

loss_function

target