52 lines
3.1 KiB
Plaintext
52 lines
3.1 KiB
Plaintext
---
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title: Sech (latest version)
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description: API reference for qiskit.pulse.library.Sech in the latest version of qiskit
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in_page_toc_min_heading_level: 1
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python_api_type: function
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python_api_name: qiskit.pulse.library.Sech
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---
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<span id="qiskit-pulse-library-sech" />
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# qiskit.pulse.library.Sech
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<Function id="qiskit.pulse.library.Sech" isDedicatedPage={true} github="https://github.com/Qiskit/qiskit/tree/stable/1.2/qiskit/pulse/library/symbolic_pulses.py#L1824-L1897" signature="qiskit.pulse.library.Sech(duration, amp, sigma, angle=0.0, name=None, zero_ends=True, limit_amplitude=None)">
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An unnormalized sech pulse.
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The sech function is centered around the halfway point of the pulse, and the envelope of the pulse is given by:
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$$
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f(x) = \text{A}\text{sech}\left(
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\frac{x-\mu}{\text{sigma}}\right) , 0 <= x < duration
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$$
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where $\text{A} = \text{amp} \times\exp\left(i\times\text{angle}\right)$, and $\mu=\text{duration}/2$.
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If zero\_ends is set to True, the output y is modified: .. math:
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```python
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y\left(x\right) \mapsto \text{A}\frac{y-y^{*}}{\text{A}-y^{*}},
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```
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where $y^{*}$ is the value of $y$ at the endpoints (at $x=-1 and :math:`x=\text{duration}+1$). This shifts the endpoints value to zero, while also rescaling to preserve the amplitude at :math:text\{duration}/2\`\`.
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**Parameters**
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* **duration** ([*int*](https://docs.python.org/3/library/functions.html#int "(in Python v3.13)") *| ParameterValueType*) – Pulse length in terms of the sampling period dt.
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* **amp** ([*float*](https://docs.python.org/3/library/functions.html#float "(in Python v3.13)") *|*[*ParameterExpression*](qiskit.circuit.ParameterExpression "qiskit.circuit.ParameterExpression")) – The magnitude of the amplitude of the pulse (the value at the midpoint duration/2).
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* **sigma** ([*float*](https://docs.python.org/3/library/functions.html#float "(in Python v3.13)") *|*[*ParameterExpression*](qiskit.circuit.ParameterExpression "qiskit.circuit.ParameterExpression")) – A measure of how wide or narrow the sech peak is in terms of dt; described mathematically in the class docstring.
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* **angle** ([*float*](https://docs.python.org/3/library/functions.html#float "(in Python v3.13)") *|*[*ParameterExpression*](qiskit.circuit.ParameterExpression "qiskit.circuit.ParameterExpression") *| None*) – The angle in radians of the complex phase factor uniformly scaling the pulse. Default value 0.
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* **name** ([*str*](https://docs.python.org/3/library/stdtypes.html#str "(in Python v3.13)") *| None*) – Display name for this pulse envelope.
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* **zero\_ends** ([*bool*](https://docs.python.org/3/library/functions.html#bool "(in Python v3.13)") *| None*) – If True, zeros the ends at x = -1, x = duration + 1, but rescales to preserve amp. Default value True.
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* **limit\_amplitude** ([*bool*](https://docs.python.org/3/library/functions.html#bool "(in Python v3.13)") *| None*) – If `True`, then limit the amplitude of the waveform to 1. The default is `True` and the amplitude is constrained to 1.
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**Returns**
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ScalableSymbolicPulse instance.
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**Return type**
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ScalableSymbolicPulse
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</Function>
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