qiskit.chemistry.components.variational_forms.CHC¶

class CHC(num_qubits=None, reps=1, ladder=False, excitations=None, entanglement='full', initial_state=None)[source]¶

This trial wavefunction is the Compact Heuristic for Chemistry.

The trial wavefunction is as defined in Ollitrault Pauline J., Chemical science 11 (2020): 6842-6855. It aims at approximating the UCC Ansatz for a lower CNOT count.

Note

It is not particle number conserving and the accuracy of the approximation decreases with the number of excitations.

Parameters

num_qubits (Optional[int]) – number of qubits
reps (int) – number of replica of basic module
ladder (bool) – use ladder of CNOTs between to indices in the entangling block
excitations (Optional[List[List[int]]]) – indices corresponding to the excitations to include in the circuit
entanglement (Union[str, List[int]]) – physical connections between the qubits
initial_state (Optional[InitialState]) – an initial state object

__init__(num_qubits=None, reps=1, ladder=False, excitations=None, entanglement='full', initial_state=None)[source]¶

Parameters

num_qubits (Optional[int]) – number of qubits
reps (int) – number of replica of basic module
ladder (bool) – use ladder of CNOTs between to indices in the entangling block
excitations (Optional[List[List[int]]]) – indices corresponding to the excitations to include in the circuit
entanglement (Union[str, List[int]]) – physical connections between the qubits
initial_state (Optional[InitialState]) – an initial state object

Methods

`__init__`([num_qubits, reps, ladder, …])	type num_qubits `Optional`[`int`]
`construct_circuit`(parameters[, q])	Construct the variational form, given its parameters.
`get_entangler_map`(map_type, num_qubits[, offset])	returns entangler map
`validate_entangler_map`(entangler_map, num_qubits)	validate entangler map

Attributes

`num_parameters`	Number of parameters of the variational form.
`num_qubits`	Number of qubits of the variational form.
`parameter_bounds`	Parameter bounds.
`preferred_init_points`	Return preferred init points.
`setting`
`support_parameterized_circuit`	Whether or not the sub-class support parameterized circuit.

construct_circuit(parameters, q=None)[source]¶

Construct the variational form, given its parameters.

Parameters

parameters (Union[ndarray, List[Parameter], ParameterVector]) – circuit parameters
q (Optional[QuantumRegister]) – Quantum Register for the circuit.

Returns

a quantum circuit with given parameters

Return type

QuantumCircuit

Raises

ValueError – the number of parameters is incorrect.
ValueError – if num_qubits has not been set and is still None
ValueError – only supports single and double excitations at the moment.

static get_entangler_map(map_type, num_qubits, offset=0)¶: returns entangler map

property num_parameters¶

Number of parameters of the variational form.

Returns: An integer indicating the number of parameters.
Return type: int

property num_qubits¶

Number of qubits of the variational form.

Returns: An integer indicating the number of qubits.
Return type: int

property parameter_bounds¶

Parameter bounds.

Returns: A list of pairs indicating the bounds, as (lower, upper). None indicates an unbounded parameter in the corresponding direction. If None is returned, problem is fully unbounded.
Return type: list

property preferred_init_points¶

Return preferred init points.

If an initial state is provided then the variational form may provide back this set of parameters which when used on the variational form should result in the overall state being that defined by the initial state

property setting¶

property support_parameterized_circuit¶

Whether or not the sub-class support parameterized circuit.

Returns: indicate the sub-class support parameterized circuit
Return type: boolean

static validate_entangler_map(entangler_map, num_qubits)¶: validate entangler map