193 lines
9.6 KiB
Plaintext
193 lines
9.6 KiB
Plaintext
---
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title: DynamicalDecoupling (v1.2)
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description: API reference for qiskit.transpiler.passes.DynamicalDecoupling in qiskit v1.2
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in_page_toc_min_heading_level: 1
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python_api_type: class
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python_api_name: qiskit.transpiler.passes.DynamicalDecoupling
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---
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# DynamicalDecoupling
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<Class id="qiskit.transpiler.passes.DynamicalDecoupling" isDedicatedPage={true} github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/transpiler/passes/scheduling/dynamical_decoupling.py#L30-L307" signature="qiskit.transpiler.passes.DynamicalDecoupling(*args, **kwargs)" modifiers="class">
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Bases: [`TransformationPass`](qiskit.transpiler.TransformationPass "qiskit.transpiler.basepasses.TransformationPass")
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Dynamical decoupling insertion pass.
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This pass works on a scheduled, physical circuit. It scans the circuit for idle periods of time (i.e. those containing delay instructions) and inserts a DD sequence of gates in those spots. These gates amount to the identity, so do not alter the logical action of the circuit, but have the effect of mitigating decoherence in those idle periods.
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As a special case, the pass allows a length-1 sequence (e.g. \[XGate()]). In this case the DD insertion happens only when the gate inverse can be absorbed into a neighboring gate in the circuit (so we would still be replacing Delay with something that is equivalent to the identity). This can be used, for instance, as a Hahn echo.
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This pass ensures that the inserted sequence preserves the circuit exactly (including global phase).
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```python
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import numpy as np
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from qiskit.circuit import QuantumCircuit
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from qiskit.circuit.library import XGate
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from qiskit.transpiler import PassManager, InstructionDurations
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from qiskit.transpiler.passes import ALAPSchedule, DynamicalDecoupling
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from qiskit.visualization import timeline_drawer
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# Because the legacy passes do not propagate the scheduling information correctly, it is
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# necessary to run a no-op "re-schedule" before the output circuits can be drawn.
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def draw(circuit):
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from qiskit import transpile
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scheduled = transpile(
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circuit,
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optimization_level=0,
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instruction_durations=InstructionDurations(),
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scheduling_method="alap",
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)
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return timeline_drawer(scheduled)
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circ = QuantumCircuit(4)
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circ.h(0)
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circ.cx(0, 1)
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circ.cx(1, 2)
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circ.cx(2, 3)
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circ.measure_all()
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durations = InstructionDurations(
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[("h", 0, 50), ("cx", [0, 1], 700), ("reset", None, 10),
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("cx", [1, 2], 200), ("cx", [2, 3], 300),
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("x", None, 50), ("measure", None, 1000)]
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)
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# balanced X-X sequence on all qubits
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dd_sequence = [XGate(), XGate()]
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pm = PassManager([ALAPSchedule(durations),
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DynamicalDecoupling(durations, dd_sequence)])
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circ_dd = pm.run(circ)
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draw(circ_dd)
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# Uhrig sequence on qubit 0
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n = 8
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dd_sequence = [XGate()] * n
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def uhrig_pulse_location(k):
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return np.sin(np.pi * (k + 1) / (2 * n + 2)) ** 2
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spacing = []
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for k in range(n):
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spacing.append(uhrig_pulse_location(k) - sum(spacing))
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spacing.append(1 - sum(spacing))
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pm = PassManager(
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[
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ALAPSchedule(durations),
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DynamicalDecoupling(durations, dd_sequence, qubits=[0], spacing=spacing),
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]
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)
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circ_dd = pm.run(circ)
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draw(circ_dd)
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```
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Dynamical decoupling initializer.
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<Admonition title="Deprecated since version 1.1.0" type="danger">
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The class `qiskit.transpiler.passes.scheduling.dynamical_decoupling.DynamicalDecoupling` is deprecated as of qiskit 1.1.0. It will be removed no earlier than 3 months after the release date. Instead, use [`PadDynamicalDecoupling`](qiskit.transpiler.passes.PadDynamicalDecoupling "qiskit.transpiler.passes.PadDynamicalDecoupling"), which performs the same function but requires scheduling and alignment analysis passes to run prior to it.
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</Admonition>
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**Parameters**
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* **durations** ([*InstructionDurations*](qiskit.transpiler.InstructionDurations "qiskit.transpiler.InstructionDurations")) – Durations of instructions to be used in scheduling.
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* **dd\_sequence** ([*list*](https://docs.python.org/3/library/stdtypes.html#list "(in Python v3.13)")*\[*[*Gate*](qiskit.circuit.Gate "qiskit.circuit.Gate")*]*) – sequence of gates to apply in idle spots.
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* **qubits** ([*list*](https://docs.python.org/3/library/stdtypes.html#list "(in Python v3.13)")*\[*[*int*](https://docs.python.org/3/library/functions.html#int "(in Python v3.13)")*]*) – physical qubits on which to apply DD. If None, all qubits will undergo DD (when possible).
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* **spacing** ([*list*](https://docs.python.org/3/library/stdtypes.html#list "(in Python v3.13)")*\[*[*float*](https://docs.python.org/3/library/functions.html#float "(in Python v3.13)")*]*) – a list of spacings between the DD gates. The available slack will be divided according to this. The list length must be one more than the length of dd\_sequence, and the elements must sum to 1. If None, a balanced spacing will be used \[d/2, d, d, …, d, d, d/2].
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* **skip\_reset\_qubits** ([*bool*](https://docs.python.org/3/library/functions.html#bool "(in Python v3.13)")) – if True, does not insert DD on idle periods that immediately follow initialized/reset qubits (as qubits in the ground state are less susceptible to decoherence).
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* **target** ([*Target*](qiskit.transpiler.Target "qiskit.transpiler.Target")) – The [`Target`](qiskit.transpiler.Target "qiskit.transpiler.Target") representing the target backend, if both `durations` and this are specified then this argument will take precedence and `durations` will be ignored.
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## Attributes
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### is\_analysis\_pass
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<Attribute id="qiskit.transpiler.passes.DynamicalDecoupling.is_analysis_pass">
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Check if the pass is an analysis pass.
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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.
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</Attribute>
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### is\_transformation\_pass
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<Attribute id="qiskit.transpiler.passes.DynamicalDecoupling.is_transformation_pass">
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Check if the pass is a transformation pass.
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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).
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</Attribute>
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## Methods
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### execute
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<Function id="qiskit.transpiler.passes.DynamicalDecoupling.execute" github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/transpiler/basepasses.py#L189-L211" signature="execute(passmanager_ir, state, callback=None)">
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Execute optimization task for input Qiskit IR.
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**Parameters**
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* **passmanager\_ir** ([*Any*](https://docs.python.org/3/library/typing.html#typing.Any "(in Python v3.13)")) – Qiskit IR to optimize.
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* **state** ([*PassManagerState*](qiskit.passmanager.PassManagerState "qiskit.passmanager.compilation_status.PassManagerState")) – State associated with workflow execution by the pass manager itself.
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* **callback** ([*Callable*](https://docs.python.org/3/library/collections.abc.html#collections.abc.Callable "(in Python v3.13)") *| None*) – A callback function which is caller per execution of optimization task.
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**Returns**
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Optimized Qiskit IR and state of the workflow.
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**Return type**
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[tuple](https://docs.python.org/3/library/stdtypes.html#tuple "(in Python v3.13)")\[[*Any*](https://docs.python.org/3/library/typing.html#typing.Any "(in Python v3.13)"), [qiskit.passmanager.compilation\_status.PassManagerState](qiskit.passmanager.PassManagerState "qiskit.passmanager.compilation_status.PassManagerState")]
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</Function>
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### name
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<Function id="qiskit.transpiler.passes.DynamicalDecoupling.name" github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/passmanager/base_tasks.py#L68-L70" signature="name()">
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Name of the pass.
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**Return type**
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[str](https://docs.python.org/3/library/stdtypes.html#str "(in Python v3.13)")
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</Function>
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### run
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<Function id="qiskit.transpiler.passes.DynamicalDecoupling.run" github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/transpiler/passes/scheduling/dynamical_decoupling.py#L153-L281" signature="run(dag)">
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Run the DynamicalDecoupling pass on dag.
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**Parameters**
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**dag** ([*DAGCircuit*](qiskit.dagcircuit.DAGCircuit "qiskit.dagcircuit.DAGCircuit")) – a scheduled DAG.
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**Returns**
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**equivalent circuit with delays interrupted by DD,**
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where possible.
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**Return type**
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[DAGCircuit](qiskit.dagcircuit.DAGCircuit "qiskit.dagcircuit.DAGCircuit")
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**Raises**
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[**TranspilerError**](transpiler#qiskit.transpiler.TranspilerError "qiskit.transpiler.TranspilerError") – if the circuit is not mapped on physical qubits.
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</Function>
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### update\_status
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<Function id="qiskit.transpiler.passes.DynamicalDecoupling.update_status" github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/transpiler/basepasses.py#L213-L221" signature="update_status(state, run_state)">
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Update workflow status.
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**Parameters**
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* **state** ([*PassManagerState*](qiskit.passmanager.PassManagerState "qiskit.passmanager.compilation_status.PassManagerState")) – Pass manager state to update.
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* **run\_state** (*RunState*) – Completion status of current task.
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**Returns**
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Updated pass manager state.
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**Return type**
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[*PassManagerState*](qiskit.passmanager.PassManagerState "qiskit.passmanager.compilation_status.PassManagerState")
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</Function>
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</Class>
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