---
title: TimeUnitConversion (v0.46)
description: API reference for qiskit.transpiler.passes.TimeUnitConversion in qiskit v0.46
source: https://eu-de.quantum.cloud.ibm.com/docs/en/api/qiskit/0.46/qiskit.transpiler.passes.TimeUnitConversion
---

# TimeUnitConversion

*class* `qiskit.transpiler.passes.TimeUnitConversion(*args, **kwargs)`

[GitHub](https://github.com/qiskit/qiskit/tree/stable/0.46/qiskit/transpiler/passes/scheduling/time_unit_conversion.py)

Bases: [`TransformationPass`](/docs/api/qiskit/0.46/qiskit.transpiler.TransformationPass "qiskit.transpiler.basepasses.TransformationPass")

Choose a time unit to be used in the following time-aware passes, and make all circuit time units consistent with that.

This pass will add a [`Instruction.duration`](/docs/api/qiskit/0.46/qiskit.circuit.Instruction#duration "qiskit.circuit.Instruction.duration") metadata to each op whose duration is known which will be used by subsequent scheduling passes for scheduling.

If `dt` (in seconds) is known to transpiler, the unit `'dt'` is chosen. Otherwise, the unit to be selected depends on what units are used in delays and instruction durations:

- `'s'`: if they are all in SI units.
- `'dt'`: if they are all in the unit `'dt'`.
- raise error: if they are a mix of SI units and `'dt'`.

TimeUnitAnalysis initializer.

**Parameters**

- **inst\_durations** ([*InstructionDurations*](/docs/api/qiskit/0.46/qiskit.transpiler.InstructionDurations "qiskit.transpiler.InstructionDurations")) – A dictionary of durations of instructions.
- **target** – The [`Target`](/docs/api/qiskit/0.46/qiskit.transpiler.Target "qiskit.transpiler.Target") representing the target backend, if both `inst_durations` and `target` are specified then this argument will take precedence and `inst_durations` will be ignored.

## 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*](https://docs.python.org/3/library/typing.html#typing.Any)) – Qiskit IR to optimize.
- **state** ([*PassManagerState*](/docs/api/qiskit/0.46/qiskit.passmanager.PassManagerState "qiskit.passmanager.compilation_status.PassManagerState")) – State associated with workflow execution by the pass manager itself.
- **callback** ([*Callable*](https://docs.python.org/3/library/collections.abc.html#collections.abc.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](https://docs.python.org/3/library/stdtypes.html#tuple)\[[*Any*](https://docs.python.org/3/library/typing.html#typing.Any), [qiskit.passmanager.compilation\_status.PassManagerState](/docs/api/qiskit/0.46/qiskit.passmanager.PassManagerState "qiskit.passmanager.compilation_status.PassManagerState")]

### name

`name()`

Name of the pass.

**Return type**

[str](https://docs.python.org/3/library/stdtypes.html#str)

### run

`run(dag)`

Run the TimeUnitAnalysis pass on dag.

**Parameters**

**dag** ([*DAGCircuit*](/docs/api/qiskit/0.46/qiskit.dagcircuit.DAGCircuit "qiskit.dagcircuit.DAGCircuit")) – DAG to be checked.

**Returns**

DAG with consistent timing and op nodes annotated with duration.

**Return type**

[DAGCircuit](/docs/api/qiskit/0.46/qiskit.dagcircuit.DAGCircuit "qiskit.dagcircuit.DAGCircuit")

**Raises**

[**TranspilerError**](/docs/api/qiskit/0.46/transpiler#qiskit.transpiler.TranspilerError "qiskit.transpiler.TranspilerError") – if the units are not unifiable

### update\_status

`update_status(state, run_state)`

Update workflow status.

**Parameters**

- **state** ([*PassManagerState*](/docs/api/qiskit/0.46/qiskit.passmanager.PassManagerState "qiskit.passmanager.compilation_status.PassManagerState")) – Pass manager state to update.
- **run\_state** (*RunState*) – Completion status of current task.

**Returns**

Updated pass manager state.

**Return type**

[*PassManagerState*](/docs/api/qiskit/0.46/qiskit.passmanager.PassManagerState "qiskit.passmanager.compilation_status.PassManagerState")