Enhancements to DRAG calibration

doc/source/protocols/drag/drag.rst

@@ -0,0 +1,94 @@
+DRAG experiments
+================
+
+In this section we show how to run Ramsey experiments using Qibocal
+
+.. _drag:
+
+
+DRAG :cite:p:`Motzoi_2009, Gambetta_2011`: pulses can be used to lower both phase and leakage errors,
+it consists in adding a quadrature component to the pulse which is proportional
+to the time derivative of the phase component. Given a pulse with a phase component :math:`\Omega_x`
+the quadrature component :math:`\Omega_y` is evaluated as
+
+.. math::
+
+    \Omega_y (t) = \beta \frac{d\Omega_x}{dt} ,
+
+where :math:`\beta` is a scaling parameter.
+
+Qibocal provides two separate protocols to extract :math:`\beta`.
+
+
+Method 1
+--------
+
+:math:`\beta` can be extracted by playing the pulse sequence composed by
+:math:`[R_X(\pi) - R_X(-\pi)]^N` for different values of :math:`\beta` as shown in  :cite:p:`Sheldon_2016`.
+The post-processing consists in measuring the probability of :math:`\ket{0}` for every :math:`\beta`
+and fitting the curve with a cosine. The correct :math:`\beta` value is the one which maximizes
+the curve.
+
+Parameters
+^^^^^^^^^^
+
+.. autoclass:: qibocal.protocols.drag.DragTuningParameters
+  :noindex:
+
+Example
+^^^^^^^
+
+.. code-block:: yaml
+
+      - id: drag tuning
+        operation: drag_tuning
+        parameters:
+            beta_start: -1
+            beta_end: 1
+            beta_step: 0.1
+            nflips: 5
+            unrolling: true
+
+
+Running this protocol you should get something like this:
+
+.. image:: drag_tuning.png
+
+
+Method 2
+--------
+
+The second method consists in playing two different sequences
+:math:`R_Y(\pi) R_X(\pi/2)` and :math:`R_X(\pi) R_Y(\pi/2)` which are two
+of the AllXY pulses which exhibit opposite sign of phase error as highlighted
+in :cite:p:`reed2013entanglementquantumerrorcorrection`.
+The post-processing consists in measuring the probability of :math:`\ket{1}` for every :math:`\beta`
+and performing a linear fit for both sequences. The correct :math:`\beta` value is the one where the two lines
+cross.
+
+Parameters
+^^^^^^^^^^
+
+.. autoclass:: qibocal.protocols.drag_simple.DragTuningSimpleParameters
+  :noindex:
+
+Example
+^^^^^^^
+
+.. code-block:: yaml
+
+      - id: drag simple
+        operation: drag_simple
+        parameters:
+            beta_start: -1
+            beta_end: 1
+            beta_step: 0.1
+            unrolling: true
+
+.. image:: drag_simple.png
+
+
+Requirements
+^^^^^^^^^^^^
+
+- :ref:`single-shot`

doc/source/protocols/index.rst

@@ -28,6 +28,7 @@ In this section we introduce the basics of all protocols supported by ``qibocal`
     dispersive_shift
     allxy
     flipping
+    drag/drag
     readout_mitigation_matrix
     readout_optimization
     standard_rb

doc/source/refs.bib

@@ -190,3 +190,53 @@ @article{Nielsen_2002
    author={Nielsen, Michael A},
    year={2002},
    month=oct, pages={249–252} }
+
+@article{Motzoi_2009,
+   title={Simple Pulses for Elimination of Leakage in Weakly Nonlinear Qubits},
+   volume={103},
+   ISSN={1079-7114},
+   url={http://dx.doi.org/10.1103/PhysRevLett.103.110501},
+   DOI={10.1103/physrevlett.103.110501},
+   number={11},
+   journal={Physical Review Letters},
+   publisher={American Physical Society (APS)},
+   author={Motzoi, F. and Gambetta, J. M. and Rebentrost, P. and Wilhelm, F. K.},
+   year={2009},
+   month=sep }
+
+
+@article{Gambetta_2011,
+   title={Analytic control methods for high-fidelity unitary operations in a weakly nonlinear oscillator},
+   volume={83},
+   ISSN={1094-1622},
+   url={http://dx.doi.org/10.1103/PhysRevA.83.012308},
+   DOI={10.1103/physreva.83.012308},
+   number={1},
+   journal={Physical Review A},
+   publisher={American Physical Society (APS)},
+   author={Gambetta, J. M. and Motzoi, F. and Merkel, S. T. and Wilhelm, F. K.},
+   year={2011},
+   month=jan }
+
+@article{Sheldon_2016,
+   title={Characterizing errors on qubit operations via iterative randomized benchmarking},
+   volume={93},
+   ISSN={2469-9934},
+   url={http://dx.doi.org/10.1103/PhysRevA.93.012301},
+   DOI={10.1103/physreva.93.012301},
+   number={1},
+   journal={Physical Review A},
+   publisher={American Physical Society (APS)},
+   author={Sheldon, Sarah and Bishop, Lev S. and Magesan, Easwar and Filipp, Stefan and Chow, Jerry M. and Gambetta, Jay M.},
+   year={2016},
+   month=jan }
+
+@misc{reed2013entanglementquantumerrorcorrection,
+      title={Entanglement and Quantum Error Correction with Superconducting Qubits},
+      author={Matthew Reed},
+      year={2013},
+      eprint={1311.6759},
+      archivePrefix={arXiv},
+      primaryClass={quant-ph},
+      url={https://arxiv.org/abs/1311.6759},
+}

src/qibocal/protocols/__init__.py

@@ -11,6 +11,7 @@
 from .dispersive_shift import dispersive_shift
 from .dispersive_shift_qutrit import dispersive_shift_qutrit
 from .drag import drag_tuning
+from .drag_simple import drag_simple
 from .flipping import flipping
 from .flux_dependence.qubit_crosstalk import qubit_crosstalk
 from .flux_dependence.qubit_flux_dependence import qubit_flux
@@ -104,4 +105,5 @@
     "standard_rb_2q_inter",
     "optimize_two_qubit_gate",
     "ramsey_zz",
+    "drag_simple",
 ]

src/qibocal/protocols/drag.py

@@ -39,6 +39,8 @@ class DragTuningParameters(Parameters):
     unrolling: bool = False
     """If ``True`` it uses sequence unrolling to deploy multiple sequences in a single instrument call.
     Defaults to ``False``."""
+    nflips: int = 1
+    """Repetitions of (Xpi - Xmpi)."""
 
 
 @dataclass
@@ -97,11 +99,17 @@ def _acquisition(
             )
             drag_negative = replace(drag, relative_phase=np.pi)
 
-            # TODO: here we can add pairs of this in a for loop
-            sequence.append((qd_channel, drag))
-            sequence.append((qd_channel, drag_negative))
+            for _ in range(params.nflips):
+                sequence.append((qd_channel, drag))
+                sequence.append((qd_channel, drag_negative))
             sequence.append(
-                (ro_channel, Delay(duration=drag.duration + drag_negative.duration))
+                (
+                    ro_channel,
+                    Delay(
+                        duration=params.nflips
+                        * (drag.duration + drag_negative.duration)
+                    ),
+                )
             )
             sequence.append((ro_channel, ro_pulse))