qiskit.aqua.operators.converters.CircuitSampler¶

class CircuitSampler(backend, statevector=None, param_qobj=False, attach_results=False)[ソース]¶

The CircuitSampler traverses an Operator and converts any CircuitStateFns into approximations of the state function by a DictStateFn or VectorStateFn using a quantum backend. Note that in order to approximate the value of the CircuitStateFn, it must 1) send state function through a depolarizing channel, which will destroy all phase information and 2) replace the sampled frequencies with square roots of the frequency, rather than the raw probability of sampling (which would be the equivalent of sampling the square of the state function, per the Born rule.

The CircuitSampler aggressively caches transpiled circuits to handle re-parameterization of the same circuit efficiently. If you are converting multiple different Operators, you are better off using a different CircuitSampler for each Operator to avoid cache thrashing.

パラメータ

backend (Union[Backend, BaseBackend, QuantumInstance]) – The quantum backend or QuantumInstance to use to sample the circuits.
statevector (Optional[bool]) – If backend is a statevector backend, whether to replace the CircuitStateFns with DictStateFns (from the counts) or VectorStateFns (from the statevector). None will set this argument automatically based on the backend.
attach_results (bool) – Whether to attach the data from the backend Results object for a given CircuitStateFn` to an execution_results field added the converted DictStateFn or VectorStateFn.
param_qobj (bool) – Whether to use Aer’s parameterized Qobj capability to avoid re-assembling the circuits.

例外

ValueError – Set statevector or param_qobj True when not supported by backend.

__init__(backend, statevector=None, param_qobj=False, attach_results=False)[ソース]¶

パラメータ

backend (Union[Backend, BaseBackend, QuantumInstance]) – The quantum backend or QuantumInstance to use to sample the circuits.
statevector (Optional[bool]) – If backend is a statevector backend, whether to replace the CircuitStateFns with DictStateFns (from the counts) or VectorStateFns (from the statevector). None will set this argument automatically based on the backend.
attach_results (bool) – Whether to attach the data from the backend Results object for a given CircuitStateFn` to an execution_results field added the converted DictStateFn or VectorStateFn.
param_qobj (bool) – Whether to use Aer’s parameterized Qobj capability to avoid re-assembling the circuits.

例外

ValueError – Set statevector or param_qobj True when not supported by backend.

Methods

`__init__`(backend[, statevector, param_qobj, …])	type backend `Union`[`Backend`, `BaseBackend`, `QuantumInstance`]
`convert`(operator[, params])	Converts the Operator to one in which the CircuitStateFns are replaced by DictStateFns or VectorStateFns.
`sample_circuits`([circuit_sfns, param_bindings])	Samples the CircuitStateFns and returns a dict associating their `id()` values to their replacement DictStateFn or VectorStateFn.
`set_backend`(backend, **kwargs)	Sets backend with configuration.

Attributes

`backend`	Returns the backend.
`quantum_instance`	Returns the quantum instance.

property backend¶

Returns the backend.

戻り値の型: Union[Backend, BaseBackend]
戻り値: The backend used by the CircuitSampler

convert(operator, params=None)[ソース]¶

Converts the Operator to one in which the CircuitStateFns are replaced by DictStateFns or VectorStateFns. Extracts the CircuitStateFns out of the Operator, caches them, calls sample_circuits below to get their converted replacements, and replaces the CircuitStateFns in operator with the replacement StateFns.

パラメータ

operator (OperatorBase) – The Operator to convert
params (Optional[Dict[Parameter, Union[float, List[float], List[List[float]]]]]) – A dictionary mapping parameters to either single binding values or lists of binding values.

戻り値の型

OperatorBase

戻り値

The converted Operator with CircuitStateFns replaced by DictStateFns or VectorStateFns.

例外

AquaError – if extracted circuits are empty.

property quantum_instance¶

Returns the quantum instance.

戻り値の型: QuantumInstance
戻り値: The QuantumInstance used by the CircuitSampler

sample_circuits(circuit_sfns=None, param_bindings=None)[ソース]¶

Samples the CircuitStateFns and returns a dict associating their id() values to their replacement DictStateFn or VectorStateFn. If param_bindings is provided, the CircuitStateFns are broken into their parameterizations, and a list of StateFns is returned in the dict for each circuit id(). Note that param_bindings is provided here in a different format than in convert, and lists of parameters within the dict is not supported, and only binding dicts which are valid to be passed into Terra can be included in this list.

パラメータ

circuit_sfns (Optional[List[CircuitStateFn]]) – The list of CircuitStateFns to sample.
param_bindings (Optional[List[Dict[Parameter, List[float]]]]) – The parameterizations to bind to each CircuitStateFn.

戻り値の型

Dict[int, Union[StateFn, List[StateFn]]]

戻り値

The dictionary mapping ids of the CircuitStateFns to their replacement StateFns.

例外

AquaError – if extracted circuits are empty.

set_backend(backend, **kwargs)[ソース]¶

Sets backend with configuration.

例外: ValueError – statevector or param_qobj are True when not supported by backend.
戻り値の型: None