From bab2648cef6a01968bdd58b624db963860edb6b5 Mon Sep 17 00:00:00 2001
From: Sanson Jones <72441937+donsano33@users.noreply.github.com>
Date: Tue, 12 Dec 2023 10:08:17 +0100
Subject: [PATCH] Remove ability to input signals in DynamicsBackend.solve

---
 qiskit_dynamics/backend/dynamics_backend.py   | 23 +++++--------------
 .../dynamics/backend/test_dynamics_backend.py | 13 ++++-------
 2 files changed, 10 insertions(+), 26 deletions(-)

diff --git a/qiskit_dynamics/backend/dynamics_backend.py b/qiskit_dynamics/backend/dynamics_backend.py
index 78771c942..f42ecad27 100644
--- a/qiskit_dynamics/backend/dynamics_backend.py
+++ b/qiskit_dynamics/backend/dynamics_backend.py
@@ -347,12 +347,10 @@ def solve(
         self,
         t_span: Array,
         y0: Union[Array, QuantumState, BaseOperator],
-        signals: Optional[
+        solve_input: Optional[
             Union[
                 List[QuantumCircuit],
                 List[Union[Schedule, ScheduleBlock]],
-                List[Signal],
-                Tuple[List[Signal], List[Signal]],
             ]
         ] = None,
         convert_results: bool = True,
@@ -363,12 +361,8 @@ def solve(
         Args:
             t_span: Time interval to integrate over.
             y0: Initial state.
-            signals: Specification of time-dependent coefficients to simulate, either in
-                     Signal format or as Qiskit Pulse Pulse schedules.
-                     If specifying in Signal format, if ``dissipator_operators is None``,
-                     specify as a list of signals for the Hamiltonian component, otherwise
-                     specify as a tuple of two lists, one for Hamiltonian components, and
-                     one for the ``dissipator_operators`` coefficients.
+            solve_input: Time evolution of the system in terms of quantum circuits or qiskit
+                         pulse schedules.
             convert_results: If ``True``, convert returned solver state results to the same class
                              as y0. If ``False``, states will be returned in the native array type
                              used by the specified solver method.
@@ -379,18 +373,13 @@ def solve(
         """
         if validate:
             _validate_run_input(
-                signals, accepted_types=(QuantumCircuit, Schedule, ScheduleBlock, Signal)
+                solve_input, accepted_types=(QuantumCircuit, Schedule, ScheduleBlock)
             )
-        signals = [
-            build_schedule(signal, self, dt=self.options.solver._dt)
-            if isinstance(signal, QuantumCircuit)
-            else signal
-            for signal in signals
-        ]
+        schedules, _ = _to_schedule_list(solve_input, backend=self)
         solver_results = self.options.solver.solve(
             t_span=t_span,
             y0=y0,
-            signals=signals,
+            signals=schedules,
             convert_results=convert_results,
             **self.options.solver_options,
         )
diff --git a/test/dynamics/backend/test_dynamics_backend.py b/test/dynamics/backend/test_dynamics_backend.py
index 66961c799..3eab39338 100644
--- a/test/dynamics/backend/test_dynamics_backend.py
+++ b/test/dynamics/backend/test_dynamics_backend.py
@@ -37,7 +37,6 @@
     _get_acquire_instruction_timings,
     _get_backend_channel_freqs,
 )
-from qiskit_dynamics.pulse import InstructionToSignals
 from ..common import QiskitDynamicsTestCase
 
 
@@ -304,17 +303,13 @@ def test_pi_pulse(self):
         self.assertDictEqual(counts, {"1": 1024})
 
     def test_solve(self):
-        """Test the ODE simulation with different signal and y0 types."""
+        """Test the ODE simulation with different input and y0 types."""
         n_samples = 100
         with pulse.build() as x_sched0:
             pulse.play(pulse.Waveform([1.0] * n_samples), pulse.DriveChannel(0))
         x_circ0 = QuantumCircuit(1)
         x_circ0.x(0)
         x_circ0.add_calibration("x", [0], x_sched0)
-        x_signal0 = InstructionToSignals(
-            dt=self.simple_backend.dt,
-            carriers=self.simple_backend.options.solver._channel_carrier_freqs,
-        ).get_signals(x_sched0)[0]
 
         y0_variety = [
             Statevector(np.array([[1.0], [0.0]])),
@@ -322,10 +317,10 @@ def test_solve(self):
             DensityMatrix(QuantumCircuit(1)),
             Choi(QuantumCircuit(1)),
         ]
-        signal_variety = [x_sched0, x_circ0, x_signal0]
-        for signal, y0 in product(signal_variety, y0_variety):
+        input_variety = [x_sched0, x_circ0]
+        for solve_input, y0 in product(input_variety, y0_variety):
             solver_results = self.simple_backend.solve(
-                t_span=[0, n_samples * self.simple_backend.dt], y0=y0, signals=[signal]
+                t_span=[0, n_samples * self.simple_backend.dt], y0=y0, solve_input=[solve_input]
             )
             if isinstance(solver_results, list):
                 assert all(result.success for result in solver_results)