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|---|---|---|
| @@ -1,59 +1,46 @@ | ||
| --- | ||
| features: | ||
| - | | ||
| Version 2 of the primitives was introduced. The emphasis of this new version is on performing | ||
| vectorized calls to the primitive run methods, so that sweeps over parameter value sets and | ||
| observables can be efficiently specified and targetted against a single parametric circuit. | ||
| .. code: python | ||
| from qiskit.circuit import Parameter, QuantumCircuit | ||
| from qiskit.primitives import StatevectorEstimator | ||
| import numpy as np | ||
| circuit = QuantumCircuit(2) | ||
| circuit.h(0) | ||
| circuit.rz(Parameter("a"), 0 | ||
| circuit.h(0) | ||
| circuit.cx(0, 1) | ||
| # define three observables | ||
| observables = ["XX", "YY", "ZZ"] | ||
| # define a sweep over parameter values, where the second axis, in this example, is broadcasted | ||
| # against observables, and the third axis is over parameters in the circuit (just one) | ||
| params = np.linspace(-np.pi, np.pi, 100).reshape(100, 1, 1) | ||
| # estimate the expectation value for all 300 combinations of observables and parameter values, | ||
| # where the pub result will have shape (100, 3) | ||
| estimator = StatevectorEstimator([(circuit, observables, parameters)]) | ||
| The estimator has gained a ``precision`` argument in the run method that specifies the targetted | ||
| precision of the expectation value estimates. The sampler has moved ``shots`` out of the options | ||
| and into the arguments of the run method. The sampler has also been changed to return the outputs | ||
| (e.g. bitstrings) from every shot, rather than providing a Counts-like return. | ||
| Version 2 of the primitives was introduced via a new base class for both the sampler and the | ||
| estimator, along with new container types for their inputs and outputs. The emphasis of this new | ||
| version is on performing vectorized calls to the primitive ``run()`` methods, so that sweeps | ||
| over parameter value sets and observables can be efficiently specified. See | ||
| :class:`~.StatevectorSampler` and :class:`~.StatevectorEstimator` for reference implementations | ||
| of the V2 primitives. | ||
| Moreover, the estimator has gained a ``precision`` argument in the :meth:`~.BaseEstimatorV2.run` | ||
| method that specifies the targeted precision of the expectation value estimates. Analagously, | ||
| the sampler has moved ``shots`` out of the options and into the arguments of the | ||
| :meth:`~.BaseSamplerV2.run` method. The sampler has also been changed to return the outputs | ||
| (e.g. bitstrings) from every shot, rather than providing a :class:`~.Counts`-like return, and | ||
| also to store data from separate :class:`~.ClassicalRegister`\s . This enables derived classes | ||
| to implement sampler support for circuits with classical control flow. | ||
| New classes introduced as a part of the new version include | ||
| The primitive V2 base classes are: | ||
| * an abstract base class :class:`.BaseSamplerV2` with reference implementation :class:`.StatevectorSampler` and | ||
| * an abstract base class :class:`.BaseEstimatorV2` with reference implementation :class:`.StatevectorEstimator`, | ||
| * :class:`.BaseSamplerV2` | ||
| * :class:`.BaseEstimatorV2` | ||
| along with a collection of container types to help define the inputs and outputs: | ||
| The new container types which are used for inputs and outputs are: | ||
| * :class:`.SamplerPub`\: primitive unified bloc (PUB) of sampler inputs | ||
| * :class:`.EstimatorPub`\: Primitive unified bloc (PUB) of estimator inputs | ||
| * :class:`.BindingsArray`\: an array-valued collection of parameter value sets to bind against a circuit | ||
| * :class:`.BindingsArray`\: an array-valued collection of parameter value sets to bind against a | ||
| circuit | ||
| * :class:`.ObservablesArray`\: an array-valued collection of observables | ||
| * :class:`.PubResult`\: the data and metadata resulting from a single PUB's execution | ||
| * :class:`.DataBin`\: A namespace to hold data from a single PUB's execution | ||
| * :class:`.BitArray`\: an array-valued collection of bitstrings in a dense format | ||
| * :class:`.PrimitiveResult`: an iterable of :class:`.PubResult`\s along with metadata | ||
| Some of the above types have corresponding union types that define exactly which formats are natively compatible | ||
| with their associated class for automatic coersion: | ||
| Some of the above types have corresponding union types that define exactly which formats are | ||
| natively compatible with their associated class for automatic coersion: | ||
| * :class:`.EstimatorPubLike`\: accepts a circuit and an observables-like, and optionionally bindings-array-like | ||
| and shots | ||
| * :class:`.EstimatorPubLike`\: accepts a circuit and an observables-like, and optionionally | ||
| bindings-array-like and shots | ||
| * :class:`.SamplerPubLike`\: accepts a circuit and optionally bindingns-array-like and shots | ||
| * :class:`.ObservablesArrayLike`\: accepts :class:`.SparsePauliOp`, dictionaries, strings of Paulis, etc. | ||
| * :class:`.BindingsArrayLike`\: accepts NumPy arrays, lists of floats, dictionaries with parameter names, etc. | ||
| * :class:`.ObservablesArrayLike`\: accepts :class:`.SparsePauliOp`, dictionaries, strings of | ||
| Paulis, etc. | ||
| * :class:`.BindingsArrayLike`\: accepts NumPy arrays, lists of floats, dictionaries with | ||
| parameter names, etc. | ||