From 772b6921577c058b5ee3fec800e93c3be357c980 Mon Sep 17 00:00:00 2001
From: Alessandro Candido <candido.ale@gmail.com>
Date: Thu, 18 Jan 2024 17:47:34 +0100
Subject: [PATCH] Remove intermediate frequency from pulse

Following @PiergiorgioButtarini removal of last usage in Qblox, in #729
---
 src/qibolab/pulses.py | 17 ++++++-----------
 tests/test_pulses.py  | 13 ++++++++-----
 2 files changed, 14 insertions(+), 16 deletions(-)

diff --git a/src/qibolab/pulses.py b/src/qibolab/pulses.py
index f1928fcb52..aab9a32ec5 100644
--- a/src/qibolab/pulses.py
+++ b/src/qibolab/pulses.py
@@ -140,36 +140,32 @@ def envelope_waveforms(
             self.envelope_waveform_q(sampling_rate),
         )
 
-    def modulated_waveform_i(self, sampling_rate=SAMPLING_RATE) -> Waveform:
+    def modulated_waveform_i(self, _if: int, sampling_rate=SAMPLING_RATE) -> Waveform:
         """The waveform of the i component of the pulse, modulated with its
         frequency."""
 
         return self.modulated_waveforms(sampling_rate)[0]
 
-    def modulated_waveform_q(self, sampling_rate=SAMPLING_RATE) -> Waveform:
+    def modulated_waveform_q(self, _if: int, sampling_rate=SAMPLING_RATE) -> Waveform:
         """The waveform of the q component of the pulse, modulated with its
         frequency."""
 
         return self.modulated_waveforms(sampling_rate)[1]
 
-    def modulated_waveforms(self, sampling_rate=SAMPLING_RATE):
+    def modulated_waveforms(self, _if: int, sampling_rate=SAMPLING_RATE):
         """A tuple with the i and q waveforms of the pulse, modulated with its
         frequency."""
 
         pulse = self.pulse
-        if abs(pulse._if) * 2 > sampling_rate:
+        if abs(_if) * 2 > sampling_rate:
             log.info(
                 f"WARNING: The frequency of pulse {pulse.id} is higher than the nyqusit frequency ({int(sampling_rate // 2)}) for the device sampling rate: {int(sampling_rate)}"
             )
         num_samples = int(np.rint(pulse.duration * sampling_rate))
         time = np.arange(num_samples) / sampling_rate
         global_phase = pulse.global_phase
-        cosalpha = np.cos(
-            2 * np.pi * pulse._if * time + global_phase + pulse.relative_phase
-        )
-        sinalpha = np.sin(
-            2 * np.pi * pulse._if * time + global_phase + pulse.relative_phase
-        )
+        cosalpha = np.cos(2 * np.pi * _if * time + global_phase + pulse.relative_phase)
+        sinalpha = np.sin(2 * np.pi * _if * time + global_phase + pulse.relative_phase)
 
         mod_matrix = np.array([[cosalpha, -sinalpha], [sinalpha, cosalpha]]) / np.sqrt(
             2
@@ -753,7 +749,6 @@ class Pulse:
     """Pulse type, as an element of PulseType enumeration."""
     qubit: int = 0
     """Qubit or coupler addressed by the pulse."""
-    _if: int = 0
 
     def __post_init__(self):
         if isinstance(self.type, str):
diff --git a/tests/test_pulses.py b/tests/test_pulses.py
index d20a444a73..a4be3e6102 100644
--- a/tests/test_pulses.py
+++ b/tests/test_pulses.py
@@ -605,6 +605,7 @@ def test_pulseshape_rectangular():
         channel=1,
         qubit=0,
     )
+    _if = 0
 
     assert pulse.duration == 50
     assert isinstance(pulse.shape, Rectangular)
@@ -622,10 +623,10 @@ def test_pulseshape_rectangular():
         pulse.amplitude * np.zeros(num_samples),
     )
     global_phase = (
-        2 * np.pi * pulse._if * pulse.start / 1e9
+        2 * np.pi * _if * pulse.start / 1e9
     )  # pulse start, duration and finish are in ns
     mod_i, mod_q = modulate(
-        i, q, num_samples, pulse._if, global_phase + pulse.relative_phase, sampling_rate
+        i, q, num_samples, _if, global_phase + pulse.relative_phase, sampling_rate
     )
 
     np.testing.assert_allclose(pulse.shape.envelope_waveform_i(sampling_rate).data, i)
@@ -649,6 +650,7 @@ def test_pulseshape_gaussian():
         channel=1,
         qubit=0,
     )
+    _if = 0
 
     assert pulse.duration == 50
     assert isinstance(pulse.shape, Gaussian)
@@ -675,7 +677,7 @@ def test_pulseshape_gaussian():
         2 * np.pi * pulse.frequency * pulse.start / 1e9
     )  # pulse start, duration and finish are in ns
     mod_i, mod_q = modulate(
-        i, q, num_samples, pulse._if, global_phase + pulse.relative_phase, sampling_rate
+        i, q, num_samples, _if, global_phase + pulse.relative_phase, sampling_rate
     )
 
     np.testing.assert_allclose(pulse.shape.envelope_waveform_i(sampling_rate).data, i)
@@ -699,6 +701,7 @@ def test_pulseshape_drag():
         channel=1,
         qubit=0,
     )
+    _if = 0
 
     assert pulse.duration == 50
     assert isinstance(pulse.shape, Drag)
@@ -728,10 +731,10 @@ def test_pulseshape_drag():
         * sampling_rate
     )
     global_phase = (
-        2 * np.pi * pulse._if * pulse.start / 1e9
+        2 * np.pi * _if * pulse.start / 1e9
     )  # pulse start, duration and finish are in ns
     mod_i, mod_q = modulate(
-        i, q, num_samples, pulse._if, global_phase + pulse.relative_phase, sampling_rate
+        i, q, num_samples, _if, global_phase + pulse.relative_phase, sampling_rate
     )
 
     np.testing.assert_allclose(pulse.shape.envelope_waveform_i(sampling_rate).data, i)