From e0120abdd2f2373b2229647c0166a6cb4cf2c915 Mon Sep 17 00:00:00 2001
From: Stavros Efthymiou <35475381+stavros11@users.noreply.github.com>
Date: Fri, 6 Dec 2024 23:48:22 +0400
Subject: [PATCH] fix: revert back to using VirtualZ

---
 .../two_qubit_interaction/chsh/pulses.py      | 36 +++++++++----------
 1 file changed, 16 insertions(+), 20 deletions(-)

diff --git a/src/qibocal/protocols/two_qubit_interaction/chsh/pulses.py b/src/qibocal/protocols/two_qubit_interaction/chsh/pulses.py
index 567bb2ee6..6c663d47b 100644
--- a/src/qibocal/protocols/two_qubit_interaction/chsh/pulses.py
+++ b/src/qibocal/protocols/two_qubit_interaction/chsh/pulses.py
@@ -21,31 +21,27 @@ def create_bell_sequence(platform, qubits, theta=np.pi / 4, bell_state=0):
     sequence += natives0.R(theta=np.pi / 2, phi=np.pi / 2)
     sequence += natives1.R(theta=np.pi / 2, phi=np.pi / 2)
 
-    cz_sequence = platform.natives.two_qubit[qubits].CZ()
-    sequence |= cz_sequence[:1]
-    phases = {ch.split("/")[0]: vz.phase for ch, vz in cz_sequence[1:]}
-    # sequence |= cz_sequence
-    # phases = {ch.split("/")[0]: 0 for ch, vz in cz_sequence[1:]}
-
-    sequence_after = natives1.R(theta=np.pi / 2, phi=phases[qubits[1]] - np.pi / 2)
-    
+    sequence |= platform.natives.two_qubit[qubits].CZ()
+
+    sequence_after = natives1.R(theta=np.pi / 2, phi=-np.pi / 2)
+
     if bell_state == 0:
-        phases[qubits[0]] += np.pi
+        phase = np.pi
     elif bell_state == 1:
-        phases[qubits[0]] += 0
+        phase = 0
     elif bell_state == 2:
-        phases[qubits[0]] += 0
-        sequence_after += natives0.R(theta=np.pi, phi=phases[qubits[0]])
+        phase = 0
+        sequence_after += natives0.R(theta=np.pi, phi=phase)
     elif bell_state == 3:
-        phases[qubits[0]] += np.pi
-        sequence_after += natives0.R(theta=np.pi, phi=phases[qubits[0]])
+        phase = np.pi
+        sequence_after += natives0.R(theta=np.pi, phi=phase)
 
-    sequence_after += natives0.R(theta=np.pi / 2, phi=phases[qubits[0]])
+    sequence_after += natives0.R(theta=np.pi / 2, phi=phase)
 
-    phases[qubits[0]] += theta
-    sequence_after += natives0.R(theta=np.pi / 2, phi=phases[qubits[0]] + np.pi)
+    phase += theta
+    sequence_after += natives0.R(theta=np.pi / 2, phi=phase + np.pi)
 
-    return sequence | sequence_after, phases
+    return sequence | sequence_after, phase
 
 
 def create_chsh_sequences(
@@ -57,13 +53,13 @@ def create_chsh_sequences(
     ro_pulses = {}
 
     for basis in readout_basis:
-        sequence, phases = create_bell_sequence(platform, qubits, theta, bell_state)
+        sequence, phase = create_bell_sequence(platform, qubits, theta, bell_state)
         measurements = PulseSequence()
         ro_pulses[basis] = {}
         for i, base in enumerate(basis):
             natives = platform.natives.single_qubit[qubits[i]]
             if base == "X":
-                sequence += natives.R(theta=np.pi / 2, phi=phases[qubits[i]] + np.pi / 2)
+                sequence += natives.R(theta=np.pi / 2, phi=phase * (1 - i) + np.pi / 2)
 
             measurement_seq = natives.MZ()
             ro_pulses[basis][qubits[i]] = measurement_seq[0][1]