qiskit.chemistry.algorithms.VQEUVCCSDFactory

class VQEUVCCSDFactory(quantum_instance, optimizer=None, initial_point=None, expectation=None, include_custom=False)

A factory to construct a VQE minimum eigensolver with UVCCSD ansatz wavefunction.

Parameters

• quantum_instance (QuantumInstance) – The quantum instance used in the minimum eigensolver.

• optimizer (Optional[Optimizer]) – A classical optimizer.

• initial_point (Optional[ndarray]) – An optional initial point (i.e. initial parameter values) for the optimizer. If None then VQE will look to the variational form for a preferred point and if not will simply compute a random one.

• expectation (Optional[ExpectationBase]) – The Expectation converter for taking the average value of the Observable over the var_form state function. When None (the default) an ExpectationFactory is used to select an appropriate expectation based on the operator and backend. When using Aer qasm_simulator backend, with paulis, it is however much faster to leverage custom Aer function for the computation but, although VQE performs much faster with it, the outcome is ideal, with no shot noise, like using a state vector simulator. If you are just looking for the quickest performance when choosing Aer qasm_simulator and the lack of shot noise is not an issue then set include_custom parameter here to True (defaults to False).

• include_custom (bool) – When expectation parameter here is None setting this to True will allow the factory to include the custom Aer pauli expectation.

__init__(quantum_instance, optimizer=None, initial_point=None, expectation=None, include_custom=False)

Parameters

• quantum_instance (QuantumInstance) – The quantum instance used in the minimum eigensolver.

• optimizer (Optional[Optimizer]) – A classical optimizer.

• initial_point (Optional[ndarray]) – An optional initial point (i.e. initial parameter values) for the optimizer. If None then VQE will look to the variational form for a preferred point and if not will simply compute a random one.

• expectation (Optional[ExpectationBase]) – The Expectation converter for taking the average value of the Observable over the var_form state function. When None (the default) an ExpectationFactory is used to select an appropriate expectation based on the operator and backend. When using Aer qasm_simulator backend, with paulis, it is however much faster to leverage custom Aer function for the computation but, although VQE performs much faster with it, the outcome is ideal, with no shot noise, like using a state vector simulator. If you are just looking for the quickest performance when choosing Aer qasm_simulator and the lack of shot noise is not an issue then set include_custom parameter here to True (defaults to False).

• include_custom (bool) – When expectation parameter here is None setting this to True will allow the factory to include the custom Aer pauli expectation.

Methods

__init__(quantum_instance[, optimizer, …])	type quantum_instance QuantumInstance
get_solver(transformation)	Returns a VQE with a UVCCSD wavefunction ansatz, based on transformation.
supports_aux_operators()	Returns whether the eigensolver generated by this factory supports auxiliary operators.

Attributes

expectation	Getter of the expectation.
include_custom	Getter of the include_custom setting for the expectation setting.
initial_point	Getter of the initial point.
optimizer	Getter of the optimizer.
quantum_instance	Getter of the quantum instance.

property expectation

Getter of the expectation.

Return type

ExpectationBase

get_solver(transformation)

Returns a VQE with a UVCCSD wavefunction ansatz, based on transformation. This works only with a BosonicTransformation.

Parameters

transformation (BosonicTransformation) – a bosonic qubit operator transformation.

Return type

MinimumEigensolver

Returns

A VQE suitable to compute the ground state of the molecule transformed by transformation.

property include_custom

Getter of the include_custom setting for the expectation setting.

Return type

bool

property initial_point

Getter of the initial point.

Return type

ndarray

property optimizer

Getter of the optimizer.

Return type

Optimizer

property quantum_instance

Getter of the quantum instance.

Return type

QuantumInstance

supports_aux_operators()

Returns whether the eigensolver generated by this factory supports auxiliary operators.