feat: Adding documentation for CPMG

doc/source/protocols/cpmg/cpmg.rst

@@ -0,0 +1,50 @@
+CPMG sequence
+=============
+
+In this section we show how to run the dynamical decoupling sequence CPMG.
+
+The CPMG sequence consists in applying N equally spaced :math:`\pi` pulses
+within two :math:`\pi` pulses. By increasing the number of :math:`\pi` pulses :math:`T_2`
+should increase until reaching the :math:`2 T_1` limit.
+
+
+The fit is again a dumped exponential of the following form:
+
+.. math::
+
+    p_e(t) = A + B  e^{ - t / T_2}
+
+
+Parameters
+^^^^^^^^^^
+
+.. autoclass:: qibocal.protocols.coherence.cpmg.CpmgParameters
+  :noindex:
+
+Example
+^^^^^^^
+
+A possible runcard to launch a CPMG experiment could be the following:
+
+.. code-block:: yaml
+
+    - id: CPMG
+      operation: cpmg
+      parameters:
+        delay_between_pulses_end: 100000
+        delay_between_pulses_start: 4
+        delay_between_pulses_step: 1000
+        n: 10
+        nshots: 1000
+
+The expected output is the following:
+
+.. image:: cpmg.png
+
+:math:`T_2` is determined by fitting the output signal using
+the formula presented above.
+
+Requirements
+^^^^^^^^^^^^
+
+- :ref:`single-shot`

doc/source/protocols/index.rst

@@ -22,6 +22,7 @@ In this section we introduce the basics of all protocols supported by ``qibocal`
     t1/t1
     t2/t2
     t2_echo/t2_echo
+    cpmg/cpmg
     flux/single
     flux/crosstalk
     singleshot

src/qibocal/protocols/coherence/cpmg.py

@@ -151,7 +151,7 @@ def _plot(data: CpmgData, target: QubitId, fit: CpmgResults = None):
         fitting_report = table_html(
             table_dict(
                 target,
-                ["T2 Spin Echo [ns]", "chi2 reduced"],
+                ["T2", "chi2 reduced"],
                 [fit.t2_spin_echo[target], fit.chi2[target]],
                 display_error=True,
             )