--- title: Transpiler Pass Plugins (latest version) description: API reference for Transpiler Pass Plugins in the latest version of qiskit-fermions source: https://eu-de.quantum.cloud.ibm.com/docs/en/api/qiskit-fermions/transpiler-passes-plugins --- # Transpiler Pass Plugins The [`F2QSynthesis`](/docs/api/qiskit-fermions/transpiler-passes-f-2-q-synthesis#qiskit_fermions.transpiler.passes.F2QSynthesis "qiskit_fermions.transpiler.passes.F2QSynthesis") transpiler pass exposes a plugin interface (see [`F2QSynthesisPlugin`](/docs/api/qiskit-fermions/transpiler-passes-synthesis-f-2-q-synthesis-plugin#qiskit_fermions.transpiler.passes.synthesis.F2QSynthesisPlugin "qiskit_fermions.transpiler.passes.synthesis.F2QSynthesisPlugin")) through which implementations for mapping fermion-based instructions to qubit-based ones can be registered. The available plugins are managed by the [`F2QSynthesisPluginManager`](/docs/api/qiskit-fermions/transpiler-passes-synthesis-f-2-q-synthesis-plugin-manager#qiskit_fermions.transpiler.passes.synthesis.F2QSynthesisPluginManager "qiskit_fermions.transpiler.passes.synthesis.F2QSynthesisPluginManager"). Choosing the right combination of synthesis plugins is crucial and the [`F2QSynthesis`](/docs/api/qiskit-fermions/transpiler-passes-f-2-q-synthesis#qiskit_fermions.transpiler.passes.F2QSynthesis "qiskit_fermions.transpiler.passes.F2QSynthesis") transpilation pass does **not** have any default plugins defined! For this, refer to the transpiler [`presets`](/docs/api/qiskit-fermions/transpiler-presets#module-qiskit_fermions.transpiler.presets "qiskit_fermions.transpiler.presets"). | | | | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | [`F2QSynthesisPlugin`](/docs/api/qiskit-fermions/transpiler-passes-synthesis-f-2-q-synthesis-plugin#qiskit_fermions.transpiler.passes.synthesis.F2QSynthesisPlugin "qiskit_fermions.transpiler.passes.synthesis.F2QSynthesisPlugin")(\*args, \*\*kwargs) | The protocol for plugins to the [`F2QSynthesis`](/docs/api/qiskit-fermions/transpiler-passes-f-2-q-synthesis#qiskit_fermions.transpiler.passes.F2QSynthesis "qiskit_fermions.transpiler.passes.F2QSynthesis") transpiler pass. | | [`F2QSynthesisPluginManager`](/docs/api/qiskit-fermions/transpiler-passes-synthesis-f-2-q-synthesis-plugin-manager#qiskit_fermions.transpiler.passes.synthesis.F2QSynthesisPluginManager "qiskit_fermions.transpiler.passes.synthesis.F2QSynthesisPluginManager")() | A simple manager of the installed fermion-to-qubit synthesis plugins. | The plugins to use at runtime have to be registered in the [`F2QSynthesis.methods`](/docs/api/qiskit-fermions/transpiler-passes-f-2-q-synthesis#qiskit_fermions.transpiler.passes.F2QSynthesis.methods "qiskit_fermions.transpiler.passes.F2QSynthesis.methods") attribute. This can be done easily through the `config` argument of [`F2QSynthesis`](/docs/api/qiskit-fermions/transpiler-passes-f-2-q-synthesis#qiskit_fermions.transpiler.passes.F2QSynthesis "qiskit_fermions.transpiler.passes.F2QSynthesis") which specifies the plugins to use from the [`F2QSynthesisPluginManager`](/docs/api/qiskit-fermions/transpiler-passes-synthesis-f-2-q-synthesis-plugin-manager#qiskit_fermions.transpiler.passes.synthesis.F2QSynthesisPluginManager "qiskit_fermions.transpiler.passes.synthesis.F2QSynthesisPluginManager") or it can be done manually by writing into [`F2QSynthesis.methods`](/docs/api/qiskit-fermions/transpiler-passes-f-2-q-synthesis#qiskit_fermions.transpiler.passes.F2QSynthesis.methods "qiskit_fermions.transpiler.passes.F2QSynthesis.methods") directly. The table below lists the builtin synthesis plugins, organized by the [`FermionicGate`](/docs/api/qiskit-fermions/circuit-fermionic-gate#qiskit_fermions.circuit.FermionicGate "qiskit_fermions.circuit.FermionicGate") that they act upon: | Circuit instruction name | Plugin method name | Reference | | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | [`Evolution`](/docs/api/qiskit-fermions/circuit-library-evolution#qiskit_fermions.circuit.library.Evolution "qiskit_fermions.circuit.library.Evolution") | `MapperFn` | [`MapperFnEvolutionSynthesis`](/docs/api/qiskit-fermions/transpiler-passes-synthesis-mapper-fn-evolution-synthesis#qiskit_fermions.transpiler.passes.synthesis.MapperFnEvolutionSynthesis "qiskit_fermions.transpiler.passes.synthesis.MapperFnEvolutionSynthesis") | | [`InitializeModes`](/docs/api/qiskit-fermions/circuit-library-initialize-modes#qiskit_fermions.circuit.library.InitializeModes "qiskit_fermions.circuit.library.InitializeModes") | `TrivialOccupation` | [`TrivialOccupationInitializeModesSynthesis`](/docs/api/qiskit-fermions/transpiler-passes-synthesis-trivial-occupation-initialize-modes-synthesis#qiskit_fermions.transpiler.passes.synthesis.TrivialOccupationInitializeModesSynthesis "qiskit_fermions.transpiler.passes.synthesis.TrivialOccupationInitializeModesSynthesis") | | [`OrbitalRotation`](/docs/api/qiskit-fermions/circuit-library-orbital-rotation#qiskit_fermions.circuit.library.OrbitalRotation "qiskit_fermions.circuit.library.OrbitalRotation") | `GivensDecomposition` | [`GivensDecompositionOrbitalRotationSynthesis`](/docs/api/qiskit-fermions/transpiler-passes-synthesis-givens-decomposition-orbital-rotation-synthesis#qiskit_fermions.transpiler.passes.synthesis.GivensDecompositionOrbitalRotationSynthesis "qiskit_fermions.transpiler.passes.synthesis.GivensDecompositionOrbitalRotationSynthesis") | | [`PrepareSlaterDeterminant`](/docs/api/qiskit-fermions/circuit-library-prepare-slater-determinant#qiskit_fermions.circuit.library.PrepareSlaterDeterminant "qiskit_fermions.circuit.library.PrepareSlaterDeterminant") | `GivensDecompositionSlater` | [`GivensDecompositionSlaterDeterminantSynthesis`](/docs/api/qiskit-fermions/transpiler-passes-synthesis-givens-decomposition-slater-determinant-synthesis#qiskit_fermions.transpiler.passes.synthesis.GivensDecompositionSlaterDeterminantSynthesis "qiskit_fermions.transpiler.passes.synthesis.GivensDecompositionSlaterDeterminantSynthesis") | | | | | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | [`GivensDecompositionOrbitalRotationSynthesis`](/docs/api/qiskit-fermions/transpiler-passes-synthesis-givens-decomposition-orbital-rotation-synthesis#qiskit_fermions.transpiler.passes.synthesis.GivensDecompositionOrbitalRotationSynthesis "qiskit_fermions.transpiler.passes.synthesis.GivensDecompositionOrbitalRotationSynthesis")() | A [`F2QSynthesisPlugin`](/docs/api/qiskit-fermions/transpiler-passes-synthesis-f-2-q-synthesis-plugin#qiskit_fermions.transpiler.passes.synthesis.F2QSynthesisPlugin "qiskit_fermions.transpiler.passes.synthesis.F2QSynthesisPlugin") for transpiling [`OrbitalRotation`](/docs/api/qiskit-fermions/circuit-library-orbital-rotation#qiskit_fermions.circuit.library.OrbitalRotation "qiskit_fermions.circuit.library.OrbitalRotation") into Givens rotations. | | [`GivensDecompositionSlaterDeterminantSynthesis`](/docs/api/qiskit-fermions/transpiler-passes-synthesis-givens-decomposition-slater-determinant-synthesis#qiskit_fermions.transpiler.passes.synthesis.GivensDecompositionSlaterDeterminantSynthesis "qiskit_fermions.transpiler.passes.synthesis.GivensDecompositionSlaterDeterminantSynthesis")(\*) | A [`F2QSynthesisPlugin`](/docs/api/qiskit-fermions/transpiler-passes-synthesis-f-2-q-synthesis-plugin#qiskit_fermions.transpiler.passes.synthesis.F2QSynthesisPlugin "qiskit_fermions.transpiler.passes.synthesis.F2QSynthesisPlugin") for transpiling [`PrepareSlaterDeterminant`](/docs/api/qiskit-fermions/circuit-library-prepare-slater-determinant#qiskit_fermions.circuit.library.PrepareSlaterDeterminant "qiskit_fermions.circuit.library.PrepareSlaterDeterminant"). | | [`MapperFnEvolutionSynthesis`](/docs/api/qiskit-fermions/transpiler-passes-synthesis-mapper-fn-evolution-synthesis#qiskit_fermions.transpiler.passes.synthesis.MapperFnEvolutionSynthesis "qiskit_fermions.transpiler.passes.synthesis.MapperFnEvolutionSynthesis")(mapper\_fn\[, ...]) | A [`F2QSynthesisPlugin`](/docs/api/qiskit-fermions/transpiler-passes-synthesis-f-2-q-synthesis-plugin#qiskit_fermions.transpiler.passes.synthesis.F2QSynthesisPlugin "qiskit_fermions.transpiler.passes.synthesis.F2QSynthesisPlugin") for transpiling [`Evolution`](/docs/api/qiskit-fermions/circuit-library-evolution#qiskit_fermions.circuit.library.Evolution "qiskit_fermions.circuit.library.Evolution") under a custom mapping. | | [`TrivialOccupationInitializeModesSynthesis`](/docs/api/qiskit-fermions/transpiler-passes-synthesis-trivial-occupation-initialize-modes-synthesis#qiskit_fermions.transpiler.passes.synthesis.TrivialOccupationInitializeModesSynthesis "qiskit_fermions.transpiler.passes.synthesis.TrivialOccupationInitializeModesSynthesis")() | A [`F2QSynthesisPlugin`](/docs/api/qiskit-fermions/transpiler-passes-synthesis-f-2-q-synthesis-plugin#qiskit_fermions.transpiler.passes.synthesis.F2QSynthesisPlugin "qiskit_fermions.transpiler.passes.synthesis.F2QSynthesisPlugin") for transpiling [`InitializeModes`](/docs/api/qiskit-fermions/circuit-library-initialize-modes#qiskit_fermions.circuit.library.InitializeModes "qiskit_fermions.circuit.library.InitializeModes") with trivial occupation. |