188 lines
6.5 KiB
Plaintext
188 lines
6.5 KiB
Plaintext
---
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title: Constant (v0.31)
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description: API reference for qiskit.pulse.Constant in qiskit v0.31
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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.pulse.Constant
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---
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# Constant
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<Class id="qiskit.pulse.Constant" isDedicatedPage={true} github="https://github.com/qiskit/qiskit/tree/stable/0.18/qiskit/pulse/library/parametric_pulses.py" signature="Constant(duration, amp, name=None)" modifiers="class">
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Bases: `qiskit.pulse.library.parametric_pulses.ParametricPulse`
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A simple constant pulse, with an amplitude value and a duration:
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$$
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f(x) = amp , 0 <= x < duration
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f(x) = 0 , elsewhere
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$$
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Initialize the constant-valued pulse.
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**Parameters**
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* **duration** (`Union`\[`int`, `ParameterExpression`]) – Pulse length in terms of the the sampling period dt.
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* **amp** (`Union`\[`complex`, `ParameterExpression`]) – The amplitude of the constant square pulse.
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* **name** (`Optional`\[`str`]) – Display name for this pulse envelope.
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## Methods
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<span id="qiskit-pulse-constant-assign" />
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### assign
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<Function id="qiskit.pulse.Constant.assign" signature="Constant.assign(parameter, value)">
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Assign one parameter to a value, which can either be numeric or another parameter expression.
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**Return type**
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`ParametricPulse`
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</Function>
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<span id="qiskit-pulse-constant-assign-parameters" />
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### assign\_parameters
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<Function id="qiskit.pulse.Constant.assign_parameters" signature="Constant.assign_parameters(value_dict)">
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Return a new ParametricPulse with parameters assigned.
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**Parameters**
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**value\_dict** (`Dict`\[`ParameterExpression`, `Union`\[`ParameterExpression`, `float`]]) – A mapping from Parameters to either numeric values or another Parameter expression.
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**Return type**
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`ParametricPulse`
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**Returns**
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New pulse with updated parameters.
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</Function>
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<span id="qiskit-pulse-constant-draw" />
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### draw
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<Function id="qiskit.pulse.Constant.draw" signature="Constant.draw(dt=None, style=None, filename=None, interp_method=None, scale=None, interactive=None, draw_title=None, backend=None, time_range=None, time_unit='dt', show_waveform_info=True, plotter='mpl2d', axis=None)">
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Plot the interpolated envelope of pulse.
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**Parameters**
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* **style** (`Optional`\[`Dict`\[`str`, `Any`]]) – Stylesheet options. This can be dictionary or preset stylesheet classes. See :py:class:\~\`qiskit.visualization.pulse\_v2.stylesheets.IQXStandard\`, :py:class:\~\`qiskit.visualization.pulse\_v2.stylesheets.IQXSimple\`, and :py:class:\~\`qiskit.visualization.pulse\_v2.stylesheets.IQXDebugging\` for details of preset stylesheets.
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* **backend** (*Optional\[*[*BaseBackend*](qiskit.providers.BaseBackend "qiskit.providers.BaseBackend")*]*) – Backend object to play the input pulse program. If provided, the plotter may use to make the visualization hardware aware.
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* **time\_range** (`Optional`\[`Tuple`\[`int`, `int`]]) – Set horizontal axis limit. Tuple `(tmin, tmax)`.
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* **time\_unit** (`str`) – The unit of specified time range either `dt` or `ns`. The unit of `ns` is available only when `backend` object is provided.
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* **show\_waveform\_info** (`bool`) – Show waveform annotations, i.e. name, of waveforms. Set `True` to show additional information about waveforms.
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* **plotter** (`str`) –
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Name of plotter API to generate an output image. One of following APIs should be specified:
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```python
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mpl2d: Matplotlib API for 2D image generation.
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Matplotlib API to generate 2D image. Charts are placed along y axis with
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vertical offset. This API takes matplotlib.axes.Axes as `axis` input.
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```
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axis and style kwargs may depend on the plotter.
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* **axis** (`Optional`\[`Any`]) – Arbitrary object passed to the plotter. If this object is provided, the plotters use a given `axis` instead of internally initializing a figure object. This object format depends on the plotter. See plotter argument for details.
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* **dt** (`Optional`\[`Any`]) – Deprecated. This argument is used by the legacy pulse drawer.
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* **filename** (`Optional`\[`Any`]) – Deprecated. This argument is used by the legacy pulse drawer. To save output image, you can call .savefig method with returned Matplotlib Figure object.
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* **interp\_method** (`Optional`\[`Any`]) – Deprecated. This argument is used by the legacy pulse drawer.
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* **scale** (`Optional`\[`Any`]) – Deprecated. This argument is used by the legacy pulse drawer.
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* **interactive** (`Optional`\[`Any`]) – Deprecated. This argument is used by the legacy pulse drawer.
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* **draw\_title** (`Optional`\[`Any`]) – Deprecated. This argument is used by the legacy pulse drawer.
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**Returns**
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Visualization output data. The returned data type depends on the `plotter`. If matplotlib family is specified, this will be a `matplotlib.pyplot.Figure` data.
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</Function>
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<span id="qiskit-pulse-constant-get-waveform" />
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### get\_waveform
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<Function id="qiskit.pulse.Constant.get_waveform" signature="Constant.get_waveform()">
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Return a Waveform with samples filled according to the formula that the pulse represents and the parameter values it contains.
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**Return type**
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`Waveform`
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</Function>
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<span id="qiskit-pulse-constant-is-parameterized" />
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### is\_parameterized
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<Function id="qiskit.pulse.Constant.is_parameterized" signature="Constant.is_parameterized()">
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Return True iff the instruction is parameterized.
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**Return type**
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`bool`
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</Function>
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<span id="qiskit-pulse-constant-validate-parameters" />
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### validate\_parameters
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<Function id="qiskit.pulse.Constant.validate_parameters" signature="Constant.validate_parameters()">
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Validate parameters.
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**Raises**
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[**PulseError**](qiskit.pulse.PulseError "qiskit.pulse.PulseError") – If the parameters passed are not valid.
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**Return type**
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`None`
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</Function>
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## Attributes
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### amp
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<Attribute id="qiskit.pulse.Constant.amp">
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The constant value amplitude.
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**Return type**
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`Union`\[`complex`, `ParameterExpression`]
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</Attribute>
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### id
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<Attribute id="qiskit.pulse.Constant.id">
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Unique identifier for this pulse.
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**Return type**
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`int`
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</Attribute>
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### limit\_amplitude
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<Attribute id="qiskit.pulse.Constant.limit_amplitude" attributeValue="True" />
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### parameters
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<Attribute id="qiskit.pulse.Constant.parameters">
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**Return type**
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`Dict`\[`str`, `Any`]
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</Attribute>
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</Class>
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