GateDirection
class qiskit.transpiler.passes.GateDirection(*args, **kwargs)
Bases: TransformationPass
Modify asymmetric gates to match the hardware coupling direction.
This pass supports replacements for the cx, cz, ecr, swap, rzx, rxx, ryy and rzz gates, using the following identities:
┌───┐┌───┐┌───┐
q_0: ──■── q_0: ┤ H ├┤ X ├┤ H ├
┌─┴─┐ = ├───┤└─┬─┘├───┤
q_1: ┤ X ├ q_1: ┤ H ├──■──┤ H ├
└───┘ └───┘ └───┘
global phase: 3π/2
┌──────┐ ┌───┐ ┌────┐┌─────┐┌──────┐┌───┐
q_0: ┤0 ├ q_0: ─┤ S ├─┤ √X ├┤ Sdg ├┤1 ├┤ H ├
│ ECR │ = ┌┴───┴┐├────┤└┬───┬┘│ Ecr │├───┤
q_1: ┤1 ├ q_1: ┤ Sdg ├┤ √X ├─┤ S ├─┤0 ├┤ H ├
└──────┘ └─────┘└────┘ └───┘ └──────┘└───┘
Note: This is done in terms of less-efficient S/SX/Sdg gates instead of the more natural
`RY(pi /2)` so we have a chance for basis translation to keep things in a discrete basis
during resynthesis, if that's what's being asked for.
┌──────┐ ┌───┐┌──────┐┌───┐
q_0: ┤0 ├ q_0: ┤ H ├┤1 ├┤ H ├
│ RZX │ = ├───┤│ RZX │├───┤
q_1: ┤1 ├ q_1: ┤ H ├┤0 ├┤ H ├
└──────┘ └───┘└──────┘└───┘
cz, swap, rxx, ryy and rzz directions are fixed by reversing their qargs order.This pass assumes that the positions of the qubits in the DAGCircuit.qubits attribute are the physical qubit indices. For example if dag.qubits[0] is qubit 0 in the CouplingMap or Target.
GateDirection pass.
Parameters
- coupling_map (CouplingMap) – Directed graph representing a coupling map.
- target (Target) – The backend target to use for this pass. If this is specified it will be used instead of the coupling map
Attributes
is_analysis_pass
Check if the pass is an analysis pass.
If the pass is an AnalysisPass, that means that the pass can analyze the DAG and write the results of that analysis in the property set. Modifications on the DAG are not allowed by this kind of pass.
is_transformation_pass
Check if the pass is a transformation pass.
If the pass is a TransformationPass, that means that the pass can manipulate the DAG, but cannot modify the property set (but it can be read).
Methods
execute
execute(passmanager_ir, state, callback=None)
Execute optimization task for input Qiskit IR.
Parameters
- passmanager_ir (Any) – Qiskit IR to optimize.
- state (PassManagerState) – State associated with workflow execution by the pass manager itself.
- callback (Callable | None) – A callback function which is caller per execution of optimization task.
Returns
Optimized Qiskit IR and state of the workflow.
Return type
tuple[Any, qiskit.passmanager.compilation_status.PassManagerState]
name
run
run(dag)
Run the GateDirection pass on dag.
Flips the cx nodes to match the directed coupling map. Modifies the input dag.
Parameters
dag (DAGCircuit) – DAG to map.
Returns
The rearranged dag for the coupling map
Return type
Raises
TranspilerError – If the circuit cannot be mapped just by flipping the cx nodes.
update_status
update_status(state, run_state)
Update workflow status.
Parameters
- state (PassManagerState) – Pass manager state to update.
- run_state (RunState) – Completion status of current task.
Returns
Updated pass manager state.
Return type