Ignore the phase reference on the DMM channel's pulses (#700)

pulser-core/pulser/sequence/sequence.py

@@ -2070,7 +2070,9 @@ def _add(
         ph_refs = {
             self._basis_ref[basis][q].phase.last_phase for q in last.targets
         }
-        if len(ph_refs) != 1:
+        if isinstance(channel_obj, DMM):
+            phase_ref = None
+        elif len(ph_refs) != 1:
             raise ValueError(
                 "Cannot do a multiple-target pulse on qubits with different "
                 "phase references for the same basis."
@@ -2326,6 +2328,8 @@ def _validate_and_adjust_pulse(
                 detuning_map = cast(
                     _DMMSchedule, self._schedule[channel]
                 ).detuning_map
+                # Ignore the phase reference for DMM
+                assert phase_ref is None
         else:
             # If channel name can't be found among _schedule keys, the
             # Sequence is parametrized and channel is a dmm_name

tests/test_sequence.py

@@ -1198,7 +1198,7 @@ def test_delay_min_duration(reg, device):
     )
 
 
-def test_phase(reg, device):
+def test_phase(reg, device, det_map):
     seq = Sequence(reg, device)
     seq.declare_channel("ch0", "raman_local", initial_target="q0")
     seq.phase_shift(-1, "q0", "q1")
@@ -1227,6 +1227,35 @@ def test_phase(reg, device):
     assert seq.current_phase_ref("q1", "digital") == 0
     assert seq.current_phase_ref("q10", "digital") == 1
 
+    # Check that the phase of DMM pulses is unaffected
+    seq.add(Pulse.ConstantPulse(100, 1, 0, 0), "ch1")
+    seq.config_detuning_map(det_map, "dmm_0")
+    det_wf = RampWaveform(100, -10, -1)
+    seq.add_dmm_detuning(det_wf, "dmm_0")
+    # We shift the phase of just one qubit, which blocks addition
+    # of new pulses on this basis
+    seq.phase_shift(1.0, "q0", basis="ground-rydberg")
+    with pytest.raises(
+        ValueError,
+        match="Cannot do a multiple-target pulse on qubits with different "
+        "phase references for the same basis.",
+    ):
+        seq.add(Pulse.ConstantPulse(100, 1, 0, 0), "ch1")
+    # But it works on the DMM
+    seq.add_dmm_detuning(det_wf, "dmm_0")
+
+    seq_samples = sample(seq)
+    # The phase on the rydberg channel matches the phase ref
+    np.testing.assert_array_equal(
+        seq_samples.channel_samples["ch1"].phase,
+        seq.current_phase_ref("q1", basis="ground-rydberg"),
+    )
+
+    # but the phase in the DMMSamples stays at zero
+    np.testing.assert_array_equal(
+        sample(seq).channel_samples["dmm_0"].phase, 0.0
+    )
+
 
 def test_align(reg, device):
     seq = Sequence(reg, device)