Preset Passmanagers

qiskit.transpiler.preset_passmanagers.level_0_pass_manager(pass_manager_config)

Level 0 pass manager: no explicit optimization other than mapping to backend.

This pass manager applies the user-given initial layout. If none is given, a trivial layout consisting of mapping the i-th virtual qubit to the i-th physical qubit is used. Any unused physical qubit is allocated as ancilla space.

The pass manager then unrolls the circuit to the desired basis, and transforms the circuit to match the coupling map.

Parameters

pass_manager_config (PassManagerConfig) – configuration of the pass manager.

Returns

a level 0 pass manager.

Raises

TranspilerError – if the passmanager config is invalid.

Return type

StagedPassManager

qiskit.transpiler.preset_passmanagers.level_1_pass_manager(pass_manager_config)

Level 1 pass manager: light optimization by simple adjacent gate collapsing.

This pass manager applies the user-given initial layout. If none is given, and a trivial layout (i-th virtual -> i-th physical) makes the circuit fit the coupling map, that is used. Otherwise, the circuit is mapped to the most densely connected coupling subgraph, and swaps are inserted to map. Any unused physical qubit is allocated as ancilla space. The pass manager then unrolls the circuit to the desired basis, and transforms the circuit to match the coupling map. Finally, optimizations in the form of adjacent gate collapse and redundant reset removal are performed.

Parameters

pass_manager_config (PassManagerConfig) – configuration of the pass manager.

Returns

a level 1 pass manager.

Raises

TranspilerError – if the passmanager config is invalid.

Return type

StagedPassManager

qiskit.transpiler.preset_passmanagers.level_2_pass_manager(pass_manager_config)

Level 2 pass manager: medium optimization by initial layout selection and gate cancellation using commutativity rules.

This pass manager applies the user-given initial layout. If none is given, a search for a perfect layout (i.e. one that satisfies all 2-qubit interactions) is conducted. If no such layout is found, qubits are laid out on the most densely connected subset which also exhibits the best gate fidelities.

The pass manager then transforms the circuit to match the coupling constraints. It is then unrolled to the basis, and any flipped cx directions are fixed. Finally, optimizations in the form of commutative gate cancellation and redundant reset removal are performed.

Parameters

pass_manager_config (PassManagerConfig) – configuration of the pass manager.

Returns

a level 2 pass manager.

Raises

TranspilerError – if the passmanager config is invalid.

Return type

StagedPassManager

qiskit.transpiler.preset_passmanagers.level_3_pass_manager(pass_manager_config)

Level 3 pass manager: heavy optimization by noise adaptive qubit mapping and gate cancellation using commutativity rules and unitary synthesis.

This pass manager applies the user-given initial layout. If none is given, a search for a perfect layout (i.e. one that satisfies all 2-qubit interactions) is conducted. If no such layout is found, and device calibration information is available, the circuit is mapped to the qubits with best readouts and to CX gates with highest fidelity.

The pass manager then transforms the circuit to match the coupling constraints. It is then unrolled to the basis, and any flipped cx directions are fixed. Finally, optimizations in the form of commutative gate cancellation, resynthesis of two-qubit unitary blocks, and redundant reset removal are performed.

Parameters

pass_manager_config (PassManagerConfig) – configuration of the pass manager.

Returns

a level 3 pass manager.

Raises

TranspilerError – if the passmanager config is invalid.

Return type

StagedPassManager

qiskit.transpiler.preset_passmanagers.generate_control_flow_options_check(layout_method=None, routing_method=None, translation_method=None, optimization_method=None, scheduling_method=None, basis_gates=(), target=None)

Generate a pass manager that, when run on a DAG that contains control flow, fails with an error message explaining the invalid options, and what could be used instead.

Returns

a pass manager that populates the contains_x properties for each of the control-flow operations, and raises an error if any of the given options do not support control flow, but a circuit with control flow is given.

Return type

PassManager

qiskit.transpiler.preset_passmanagers.generate_error_on_control_flow(message)

Get a pass manager that always raises an error if control flow is present in a given circuit.

qiskit.transpiler.preset_passmanagers.generate_unroll_3q(target, basis_gates=None, approximation_degree=None, unitary_synthesis_method='default', unitary_synthesis_plugin_config=None, hls_config=None, qubits_initially_zero=True)

Generate an unroll >3q PassManager

Parameters

• target (Target) – the Target object representing the backend
• basis_gates (list) – A list of str gate names that represent the basis gates on the backend target
• approximation_degree (Optional[float]) – The heuristic approximation degree to use. Can be between 0 and 1.
• unitary_synthesis_method (str) – The unitary synthesis method to use. You can see a list of installed plugins with unitary_synthesis_plugin_names().
• unitary_synthesis_plugin_config (dict) – The optional dictionary plugin configuration, this is plugin specific refer to the specified plugin’s documentation for how to use.
• hls_config (HLSConfig) – An optional configuration class to use for HighLevelSynthesis pass. Specifies how to synthesize various high-level objects.
• qubits_initially_zero (bool) – Indicates whether the input circuit is zero-initialized.

Returns

The unroll 3q or more pass manager

Return type

PassManager

qiskit.transpiler.preset_passmanagers.generate_embed_passmanager(coupling_map)

Generate a layout embedding PassManager

This is used to generate a PassManager object that can be used to expand and apply an initial layout to a circuit

Parameters

coupling_map (Union[CouplingMap, Target) – The coupling map for the backend to embed the circuit to.

Returns

The embedding passmanager that assumes the layout property

set has been set in earlier stages

Return type

PassManager

qiskit.transpiler.preset_passmanagers.generate_routing_passmanager(routing_pass, target, coupling_map=None, vf2_call_limit=None, backend_properties=None, seed_transpiler=None, check_trivial=False, use_barrier_before_measurement=True, vf2_max_trials=None)

Generate a routing PassManager

Parameters

• routing_pass (TransformationPass) – The pass which will perform the routing
• target (Target) – the Target object representing the backend
• coupling_map (CouplingMap) – The coupling map of the backend to route for
• vf2_call_limit (int) – The internal call limit for the vf2 post layout pass. If this is None or 0 the vf2 post layout will not be run.
• backend_properties (BackendProperties) – Properties of a backend to synthesize for (e.g. gate fidelities).
• seed_transpiler (int) – Sets random seed for the stochastic parts of the transpiler.
• check_trivial (bool) – If set to true this will condition running the VF2PostLayout pass after routing on whether a trivial layout was tried and was found to not be perfect. This is only needed if the constructed pass manager runs TrivialLayout as a first layout attempt and uses it if it’s a perfect layout (as is the case with preset pass manager level 1).
• use_barrier_before_measurement (bool) – If true (the default) the BarrierBeforeFinalMeasurements transpiler pass will be run prior to the specified pass in the routing_pass argument.
• vf2_max_trials (int) – The maximum number of trials to run VF2 when evaluating the vf2 post layout pass. If this is None or 0 the vf2 post layout will not be run.

Returns

The routing pass manager

Return type

PassManager

qiskit.transpiler.preset_passmanagers.generate_pre_op_passmanager(target=None, coupling_map=None, remove_reset_in_zero=False)

Generate a pre-optimization loop PassManager

This pass manager will check to ensure that directionality from the coupling map is respected

Parameters

• target (Target) – the Target object representing the backend
• coupling_map (CouplingMap) – The coupling map to use
• remove_reset_in_zero (bool) – If True include the remove reset in zero pass in the generated PassManager

Returns

The pass manager

Return type

PassManager

qiskit.transpiler.preset_passmanagers.generate_translation_passmanager(target, basis_gates=None, method='translator', approximation_degree=None, coupling_map=None, backend_props=None, unitary_synthesis_method='default', unitary_synthesis_plugin_config=None, hls_config=None, qubits_initially_zero=True)

Generate a basis translation PassManager

Parameters

• target (Target) – the Target object representing the backend
• basis_gates (list) – A list of str gate names that represent the basis gates on the backend target
• method (str) – The basis translation method to use
• approximation_degree (Optional[float]) – The heuristic approximation degree to use. Can be between 0 and 1.
• coupling_map (CouplingMap) – the coupling map of the backend in case synthesis is done on a physical circuit. The directionality of the coupling_map will be taken into account if pulse_optimize is True/None and natural_direction is True/None.
• unitary_synthesis_plugin_config (dict) – The optional dictionary plugin configuration, this is plugin specific refer to the specified plugin’s documentation for how to use.
• backend_props (BackendProperties) – Properties of a backend to synthesize for (e.g. gate fidelities).
• unitary_synthesis_method (str) – The unitary synthesis method to use. You can see a list of installed plugins with unitary_synthesis_plugin_names().
• hls_config (HLSConfig) – An optional configuration class to use for HighLevelSynthesis pass. Specifies how to synthesize various high-level objects.
• qubits_initially_zero (bool) – Indicates whether the input circuit is zero-initialized.

Returns

The basis translation pass manager

Return type

PassManager

Raises

TranspilerError – If the method kwarg is not a valid value

qiskit.transpiler.preset_passmanagers.generate_scheduling(instruction_durations, scheduling_method, timing_constraints, inst_map, target=None)

Generate a post optimization scheduling PassManager

Parameters

• instruction_durations (dict) – The dictionary of instruction durations
• scheduling_method (str) – The scheduling method to use, can either be 'asap'/'as_soon_as_possible' or 'alap'/'as_late_as_possible'
• timing_constraints (TimingConstraints) – Hardware time alignment restrictions.
• inst_map (InstructionScheduleMap) – DEPRECATED. Mapping object that maps gate to schedule.
• target (Target) – The Target object representing the backend

Returns

The scheduling pass manager

Return type

PassManager

Raises

TranspilerError – If the scheduling_method kwarg is not a valid value