qiskit/releasenotes/notes/1.3/cphase-rzz-equivalence-e8af...

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---
features_circuits:
- |
The standard equivalence library (:data:`.SessionEquivalenceLibrary`) now has rules that can
directly convert between Qiskit's standard-library 2q continuous Ising-type interactions (e.g.
:class:`.CPhaseGate`, :class:`.RZZGate`, :class:`.RZXGate`, and so on) using local equivalence
relations. Previously, several of these conversions would go via a 2-CX form, which resulted
in less efficient circuit generation.
.. note::
In general, the :class:`.BasisTranslator` is not guaranteed to find the "best" equivalence
relation for a given :class:`.Target`, but will always find an equivalence if one exists. We
rely on more expensive resynthesis and gate-optimization passes in the transpiler to improve
the output. These passes are currently not as effective for basis sets with a continuously
parametrized two-qubit interaction as they are for discrete super-controlled two-qubit
interactions.