Merge pull request #1014 from qiboteam/coupler_chevron_improvements

coupler_chevron improvements

Author: hay-k

src/qibocal/protocols/couplers/coupler_chevron.py

@@ -1,10 +1,7 @@
-from dataclasses import dataclass
-from typing import Optional
-
 import numpy as np
 from qibolab import AcquisitionType, AveragingMode, ExecutionParameters
 from qibolab.platform import Platform
-from qibolab.pulses import PulseSequence
+from qibolab.pulses import PulseSequence, PulseType
 from qibolab.qubits import QubitPairId
 from qibolab.sweeper import Parameter, Sweeper, SweeperType
 
@@ -18,25 +15,8 @@
 from ..two_qubit_interaction.utils import order_pair
 
 
-@dataclass
-class ChevronCouplersParameters(ChevronParameters):
-
-    native_gate: Optional[str] = "CZ"
-    """Native gate to implement, CZ or iSWAP."""
-
-    """ChevronCouplers protocol parameters.
-
-    Amplitude and duration are referred to the coupler pulse.
-    """
-
-
-@dataclass
-class ChevronCouplersData(ChevronData):
-    """Data structure for chevron couplers protocol."""
-
-
-def _aquisition(
-    params: ChevronCouplersParameters,
+def _acquisition(
+    params: ChevronParameters,
     platform: Platform,
     targets: list[QubitPairId],
 ) -> ChevronData:
@@ -50,7 +30,7 @@ def _aquisition(
         targets (list): List of pairs to use sequentially.
 
     Returns:
-        ChevronCouplersData: Acquisition data.
+        ChevronData: Acquisition data.
     """
     # define the parameter to sweep and its range:
     delta_amplitude_range = np.arange(
@@ -62,29 +42,27 @@ def _aquisition(
         params.duration_min, params.duration_max, params.duration_step
     )
 
-    # create a DataUnits object to store the results,
     data = ChevronData()
-    # sort high and low frequency qubit
     for pair in targets:
         sequence = PulseSequence()
 
         ordered_pair = order_pair(pair, platform)
 
-        # initialize in system in 11(CZ) or 10(iSWAP) state
-        if params.native_gate == "CZ":
+        # initialize system to state 11(CZ) or 10(iSWAP)
+        if params.native == "CZ":
             initialize_lowfreq = platform.create_RX_pulse(ordered_pair[0], start=0)
             sequence.add(initialize_lowfreq)
 
         initialize_highfreq = platform.create_RX_pulse(ordered_pair[1], start=0)
 
         sequence.add(initialize_highfreq)
 
-        if params.native_gate == "CZ":
+        if params.native == "CZ":
             native_gate, _ = platform.create_CZ_pulse_sequence(
                 (ordered_pair[1], ordered_pair[0]),
                 start=sequence.finish + params.dt,
             )
-        elif params.native_gate == "iSWAP":
+        elif params.native == "iSWAP":
             native_gate, _ = platform.create_iSWAP_pulse_sequence(
                 (ordered_pair[1], ordered_pair[0]),
                 start=sequence.finish + params.dt,
@@ -103,56 +81,61 @@ def _aquisition(
 
         sequence += ro_pulse1 + ro_pulse2
 
+        coupler_flux_pulses = [p for p in native_gate.coupler_pulses(*pair)]
+        assert (
+            len(coupler_flux_pulses) == 1
+        ), f"coupler_chevron expects exactly one coupler flux pulse, but {len(coupler_flux_pulses)} are present."
+        qubit_flux_pulses = [
+            p for p in native_gate.get_qubit_pulses(*pair) if p.type is PulseType.FLUX
+        ]
+        assert all(
+            len(list(filter(lambda x: x.qubit == q, qubit_flux_pulses))) < 2
+            for q in pair
+        ), f"coupler_chevron expects no more than 1 flux pulse for each qubit, but more are present for the pair {pair}"
         sweeper_amplitude = Sweeper(
             Parameter.amplitude,
             delta_amplitude_range,
-            pulses=[p for p in native_gate.coupler_pulses(*pair)][:1],
+            pulses=coupler_flux_pulses,
             type=SweeperType.FACTOR,
         )
         sweeper_duration = Sweeper(
             Parameter.duration,
             delta_duration_range,
-            pulses=[p for p in native_gate.coupler_pulses(*pair)],
+            pulses=coupler_flux_pulses + qubit_flux_pulses,
         )
 
-        # repeat the experiment as many times as defined by nshots
         results = platform.sweep(
             sequence,
             ExecutionParameters(
                 nshots=params.nshots,
-                acquisition_type=AcquisitionType.INTEGRATION,
+                acquisition_type=AcquisitionType.DISCRIMINATION,
                 averaging_mode=AveragingMode.CYCLIC,
             ),
             sweeper_duration,
             sweeper_amplitude,
         )
 
-        # TODO: Explore probabilities instead of magnitude
         data.register_qubit(
             ordered_pair[0],
             ordered_pair[1],
             delta_duration_range,
             delta_amplitude_range * data.native_amplitude[ordered_pair],
-            results[ordered_pair[0]].magnitude,
-            results[ordered_pair[1]].magnitude,
+            results[ordered_pair[0]].probability(state=1),
+            results[ordered_pair[1]].probability(state=1),
         )
+    data.label = "Probability of state |1>"
 
     return data
 
 
-@dataclass
-class ChevronCouplersResults(Results):
-    """Empty fitting outputs for chevron couplers is not implemented in this case."""
-
-
-def _fit(data: ChevronCouplersData) -> ChevronCouplersResults:
-    """ "Results for ChevronCouplers."""
-    return ChevronCouplersResults()
+def _fit(data: ChevronData) -> Results:
+    """Results for ChevronCouplers."""
+    return Results()
 
 
-def plot(data: ChevronCouplersData, fit: ChevronCouplersResults, target):
+def plot(data: ChevronData, fit: Results, target):
     return _plot(data, None, target)
 
 
-coupler_chevron = Routine(_aquisition, _fit, plot, two_qubit_gates=True)
+coupler_chevron = Routine(_acquisition, _fit, plot, two_qubit_gates=True)
 """Coupler cz/swap flux routine."""

src/qibocal/protocols/two_qubit_interaction/chevron/chevron.py

@@ -109,6 +109,9 @@ class ChevronData(Data):
     """Sweetspot value for high frequency qubit."""
     data: dict[QubitPairId, npt.NDArray[ChevronType]] = field(default_factory=dict)
 
+    label: Optional[str] = None
+    """Label for the data."""
+
     def register_qubit(self, low_qubit, high_qubit, length, amp, prob_low, prob_high):
         """Store output for single qubit."""
         size = len(length) * len(amp)
@@ -308,7 +311,7 @@ def _plot(data: ChevronData, fit: ChevronResults, target: QubitPairId):
     fig.update_layout(
         xaxis_title="Duration [ns]",
         xaxis2_title="Duration [ns]",
-        yaxis_title="Amplitude [a.u.]",
+        yaxis_title=data.label or "Amplitude [a.u.]",
         legend=dict(orientation="h"),
     )
     fig.update_layout(

tests/runcards/protocols_couplers.yml

@@ -66,7 +66,7 @@ actions:
       duration_min: 50
       duration_max: 100
       duration_step: 10
-      native_gate: "CZ"
+      native: "CZ"
       dt: 5
       nshots: 10
 
@@ -81,6 +81,6 @@ actions:
       duration_min: 50
       duration_max: 100
       duration_step: 10
-      native_gate: "iSWAP"
+      native: "iSWAP"
       dt: 5
       nshots: 10