255 lines
11 KiB
Plaintext
255 lines
11 KiB
Plaintext
---
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title: T1Fitter
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description: API reference for qiskit.ignis.characterization.T1Fitter
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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.ignis.characterization.T1Fitter
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---
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# qiskit.ignis.characterization.T1Fitter
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<Class id="qiskit.ignis.characterization.T1Fitter" isDedicatedPage={true} github="https://github.com/qiskit-community/qiskit-ignis/tree/stable/0.6/qiskit/ignis/characterization/coherence/fitters.py" signature="T1Fitter(backend_result, xdata, qubits, fit_p0, fit_bounds, time_unit='micro-seconds')" modifiers="class">
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Estimate T1, based on experiments outcomes,
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The experiments were created by t1\_circuits, and executed on the device.
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The probabilities of measuring 1 is assumed to be of the form
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$$
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f(t) = A\mathrm{e}^{-t/T_1}+B,
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$$
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for unknown parameters A, B, and T1.
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**Parameters**
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* **backend\_result** (`Result`) – result of execution of t1\_circuits on the backend.
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* **xdata** (`Union`\[`List`\[`float`], `array`]) – delay times of the T1 circuits.
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* **qubits** (`List`\[`int`]) – indices of the qubits whose T1‘s are to be measured.
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* **fit\_p0** (`List`\[`float`]) – initial values to the fit parameters, where the order is $(A, T_1, B)$.
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* **fit\_bounds** (`Tuple`\[`List`\[`float`], `List`\[`float`]]) – bounds on the parameters to fit. The first tuple is the lower bounds, in the order $(A, T_1, B)$. The second tuple is the upper bounds.
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* **time\_unit** (`str`) – unit of delay times in xdata.
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### \_\_init\_\_
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<Function id="qiskit.ignis.characterization.T1Fitter.__init__" signature="__init__(backend_result, xdata, qubits, fit_p0, fit_bounds, time_unit='micro-seconds')">
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Initialize self. See help(type(self)) for accurate signature.
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</Function>
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## Methods
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| --------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------- |
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| [`__init__`](#qiskit.ignis.characterization.T1Fitter.__init__ "qiskit.ignis.characterization.T1Fitter.__init__")(backend\_result, xdata, qubits, …) | Initialize self. |
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| [`add_data`](#qiskit.ignis.characterization.T1Fitter.add_data "qiskit.ignis.characterization.T1Fitter.add_data")(results\[, recalc, refit]) | Add new execution results to previous execution results |
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| [`fit_data`](#qiskit.ignis.characterization.T1Fitter.fit_data "qiskit.ignis.characterization.T1Fitter.fit_data")(\[qid, p0, bounds, series]) | Fit the curve. |
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| [`plot`](#qiskit.ignis.characterization.T1Fitter.plot "qiskit.ignis.characterization.T1Fitter.plot")(qind\[, series, ax, show\_plot]) | Plot coherence data. |
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| [`time`](#qiskit.ignis.characterization.T1Fitter.time "qiskit.ignis.characterization.T1Fitter.time")(\[qid, series]) | Return the characteristic time for the given qubit and series |
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| [`time_err`](#qiskit.ignis.characterization.T1Fitter.time_err "qiskit.ignis.characterization.T1Fitter.time_err")(\[qid, series]) | Return the error of characteristic time for the given qubit and series |
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## Attributes
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| ------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------- |
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| [`backend_result`](#qiskit.ignis.characterization.T1Fitter.backend_result "qiskit.ignis.characterization.T1Fitter.backend_result") | Return the execution results |
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| [`description`](#qiskit.ignis.characterization.T1Fitter.description "qiskit.ignis.characterization.T1Fitter.description") | Return the fitter’s purpose, e.g. |
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| [`fit_fun`](#qiskit.ignis.characterization.T1Fitter.fit_fun "qiskit.ignis.characterization.T1Fitter.fit_fun") | Return the function used in the fit, e.g. |
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| [`measured_qubits`](#qiskit.ignis.characterization.T1Fitter.measured_qubits "qiskit.ignis.characterization.T1Fitter.measured_qubits") | Return the indices of the qubits to be characterized |
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| [`params`](#qiskit.ignis.characterization.T1Fitter.params "qiskit.ignis.characterization.T1Fitter.params") | Return the fit function parameters that were calculated by curve\_fit |
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| [`params_err`](#qiskit.ignis.characterization.T1Fitter.params_err "qiskit.ignis.characterization.T1Fitter.params_err") | Return the error of the fit function parameters |
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| [`series`](#qiskit.ignis.characterization.T1Fitter.series "qiskit.ignis.characterization.T1Fitter.series") | Return the list of series for the data |
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| [`xdata`](#qiskit.ignis.characterization.T1Fitter.xdata "qiskit.ignis.characterization.T1Fitter.xdata") | Return the data points on the x-axis, the independenet parameter which is fit against |
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| [`ydata`](#qiskit.ignis.characterization.T1Fitter.ydata "qiskit.ignis.characterization.T1Fitter.ydata") | Return the data points on the y-axis |
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### add\_data
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<Function id="qiskit.ignis.characterization.T1Fitter.add_data" signature="add_data(results, recalc=True, refit=True)">
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Add new execution results to previous execution results
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**Parameters**
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* **results** (`Union`\[`Result`, `List`\[`Result`]]) – new execution results
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* **recalc** (`bool`) – whether tp recalculate the data
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* **refit** (`bool`) – whether to refit the data
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</Function>
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### backend\_result
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<Attribute id="qiskit.ignis.characterization.T1Fitter.backend_result">
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Return the execution results
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**Return type**
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`Union`\[`Result`, `List`\[`Result`]]
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</Attribute>
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### description
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<Attribute id="qiskit.ignis.characterization.T1Fitter.description">
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Return the fitter’s purpose, e.g. ‘T1’
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**Return type**
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`str`
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</Attribute>
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### fit\_data
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<Function id="qiskit.ignis.characterization.T1Fitter.fit_data" signature="fit_data(qid=- 1, p0=None, bounds=None, series=None)">
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Fit the curve.
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Compute self.\_params and self.\_params\_err
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**Parameters**
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* **qid** (`int`) – qubit for fitting. If -1 fit for all the qubits
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* **p0** (`Optional`\[`List`\[`float`]]) – initial guess, equivalent to p0 in scipy.optimize
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* **bounds** (`Optional`\[`Tuple`\[`List`\[`float`], `List`\[`float`]]]) – bounds, equivalent to bounds in scipy.optimize
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* **series** (`Optional`\[`str`]) – series to fit (if None fit all)
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</Function>
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### fit\_fun
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<Attribute id="qiskit.ignis.characterization.T1Fitter.fit_fun">
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Return the function used in the fit, e.g. BaseFitter.\_exp\_fit\_fun
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**Return type**
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`Callable`
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</Attribute>
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### measured\_qubits
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<Attribute id="qiskit.ignis.characterization.T1Fitter.measured_qubits">
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Return the indices of the qubits to be characterized
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**Return type**
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`List`\[`int`]
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</Attribute>
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### params
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<Attribute id="qiskit.ignis.characterization.T1Fitter.params">
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Return the fit function parameters that were calculated by curve\_fit
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**Return type**
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`List`\[`float`]
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</Attribute>
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### params\_err
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<Attribute id="qiskit.ignis.characterization.T1Fitter.params_err">
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Return the error of the fit function parameters
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**Return type**
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`List`\[`float`]
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</Attribute>
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### plot
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<Function id="qiskit.ignis.characterization.T1Fitter.plot" signature="plot(qind, series='0', ax=None, show_plot=False)">
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Plot coherence data.
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**Parameters**
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* **qind** – qubit index to plot
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* **series** – which series to plot (if list then plot multiple)
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* **ax** – plot axes
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* **show\_plot** – whether to call plt.show()
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**Returns**
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The axes object
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**Return type**
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Axes
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**Raises**
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**ImportError** – if matplotlib is not installed
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</Function>
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### series
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<Attribute id="qiskit.ignis.characterization.T1Fitter.series">
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Return the list of series for the data
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**Return type**
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`Optional`\[`List`\[`str`]]
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</Attribute>
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### time
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<Function id="qiskit.ignis.characterization.T1Fitter.time" signature="time(qid=- 1, series='0')">
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Return the characteristic time for the given qubit and series
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**Parameters**
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* **qid** (`int`) – the qubit index (or all qubits if -1)
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* **series** (`str`) – the series to get
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**Return type**
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`Union`\[`float`, `List`\[`float`]]
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**Returns**
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The characteristic time of the qubit, or all qubits
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</Function>
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### time\_err
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<Function id="qiskit.ignis.characterization.T1Fitter.time_err" signature="time_err(qid=- 1, series='0')">
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Return the error of characteristic time for the given qubit and series
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**Parameters**
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* **qid** (`int`) – the qubit index (or all qubits if -1)
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* **series** (`str`) – the series to get
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**Return type**
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`Union`\[`float`, `List`\[`float`]]
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**Returns**
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The error of the characteristic time of the qubit, or all qubits
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</Function>
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### xdata
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<Attribute id="qiskit.ignis.characterization.T1Fitter.xdata">
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Return the data points on the x-axis, the independenet parameter which is fit against
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**Return type**
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`Union`\[`List`\[`float`], `array`]
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</Attribute>
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### ydata
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<Attribute id="qiskit.ignis.characterization.T1Fitter.ydata">
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Return the data points on the y-axis
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The data points are returning in the form of a list of dictionaries:
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> * **ydata\[i]\[‘mean’] is a list, where item**
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>
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> no. j is the probability of success of qubit i for a circuit that lasts xdata\[j].
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>
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> * **ydata\[i]\[‘std’] is a list, where ydata\[‘std’]\[j] is the**
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>
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> standard deviation of the success of qubit i.
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**Return type**
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`List`\[`Dict`]
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</Attribute>
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</Class>
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