Remove use of .device from cirq-aqt (#4812)

Second part of #4744 

As far as I can tell there was just one use of `.device` in cirq-aqt in the form of an assertion that the attached device to a circuit was in fact a `cirq.IonDevice` where no call to validate ever took place. Also somewhat confusingly the number of qubits used in simulation would be dictated by the device qubit count instead of the circuit qubit count which could lead to some confusion on the users end.

I've gone ahead and just removed the use of device to revert this confusing behavior (which does make this a breaking change).

Author: MichaelBroughton

cirq-aqt/cirq_aqt/aqt_sampler.py

@@ -198,11 +198,10 @@ def run_sweep(
         # TODO: Use measurement name from circuit.
         # Github issue: https://github.com/quantumlib/Cirq/issues/2199
         meas_name = 'm'
-        assert isinstance(program.device, cirq.IonDevice)
         trial_results: List[cirq.Result] = []
         for param_resolver in cirq.to_resolvers(params):
             id_str = uuid.uuid1()
-            num_qubits = len(program.device.qubits)
+            num_qubits = len(program.all_qubits())
             json_str = self._generate_json(circuit=program, param_resolver=param_resolver)
             results = self._send_json(
                 json_str=json_str, id_str=id_str, repetitions=repetitions, num_qubits=num_qubits

cirq-aqt/cirq_aqt/aqt_sampler_test.py

@@ -105,8 +105,8 @@ def test_aqt_sampler_error_handling():
             max_angle = np.pi
             repetitions = 10
             sampler = AQTSampler(remote_host="http://localhost:5000", access_token='testkey')
-            device, qubits = get_aqt_device(1)
-            circuit = cirq.Circuit(cirq.X(qubits[0]) ** theta, device=device)
+            _, qubits = get_aqt_device(1)
+            circuit = cirq.Circuit(cirq.X(qubits[0]) ** theta)
             sweep = cirq.Linspace(key='theta', start=0.1, stop=max_angle / np.pi, length=num_points)
             with pytest.raises(RuntimeError):
                 _results = sampler.run_sweep(circuit, params=sweep, repetitions=repetitions)
@@ -117,10 +117,10 @@ def test_aqt_sampler_empty_circuit():
     max_angle = np.pi
     repetitions = 1000
     num_qubits = 4
-    device, _qubits = get_aqt_device(num_qubits)
+    _, _qubits = get_aqt_device(num_qubits)
     sampler = AQTSamplerLocalSimulator()
     sampler.simulate_ideal = True
-    circuit = cirq.Circuit(device=device)
+    circuit = cirq.Circuit()
     sweep = cirq.Linspace(key='theta', start=0.1, stop=max_angle / np.pi, length=num_points)
     with pytest.raises(RuntimeError):
         _results = sampler.run_sweep(circuit, params=sweep, repetitions=repetitions)
@@ -141,8 +141,8 @@ def test_aqt_sampler():
         max_angle = np.pi
         repetitions = 10
         sampler = AQTSampler(remote_host="http://localhost:5000", access_token='testkey')
-        device, qubits = get_aqt_device(1)
-        circuit = cirq.Circuit(cirq.X(qubits[0]) ** theta, device=device)
+        _, qubits = get_aqt_device(1)
+        circuit = cirq.Circuit(cirq.X(qubits[0]) ** theta)
         sweep = cirq.Linspace(key='theta', start=0.1, stop=max_angle / np.pi, length=num_points)
         results = sampler.run_sweep(circuit, params=sweep, repetitions=repetitions)
         excited_state_probs = np.zeros(num_points)
@@ -160,10 +160,18 @@ def test_aqt_sampler_sim():
     max_angle = np.pi
     repetitions = 1000
     num_qubits = 4
-    device, qubits = get_aqt_device(num_qubits)
+    _, qubits = get_aqt_device(num_qubits)
     sampler = AQTSamplerLocalSimulator()
     sampler.simulate_ideal = True
-    circuit = cirq.Circuit(cirq.X(qubits[3]) ** theta, device=device)
+    circuit = cirq.Circuit(
+        cirq.X(qubits[3]) ** theta,
+        cirq.X(qubits[0]),
+        cirq.X(qubits[0]),
+        cirq.X(qubits[1]),
+        cirq.X(qubits[1]),
+        cirq.X(qubits[2]),
+        cirq.X(qubits[2]),
+    )
     circuit.append(cirq.PhasedXPowGate(phase_exponent=0.5, exponent=-0.5).on(qubits[0]))
     circuit.append(cirq.PhasedXPowGate(phase_exponent=0.5, exponent=0.5).on(qubits[0]))
     sweep = cirq.Linspace(key='theta', start=0.1, stop=max_angle / np.pi, length=num_points)
@@ -179,20 +187,26 @@ def test_aqt_sampler_sim_xtalk():
     max_angle = np.pi
     repetitions = 100
     num_qubits = 4
-    device, qubits = get_aqt_device(num_qubits)
+    _, qubits = get_aqt_device(num_qubits)
     sampler = AQTSamplerLocalSimulator()
     sampler.simulate_ideal = False
-    circuit = cirq.Circuit(cirq.X(qubits[0]), cirq.X(qubits[3]), cirq.X(qubits[2]), device=device)
+    circuit = cirq.Circuit(
+        cirq.X(qubits[0]),
+        cirq.X(qubits[1]),
+        cirq.X(qubits[1]),
+        cirq.X(qubits[3]),
+        cirq.X(qubits[2]),
+    )
     sweep = cirq.Linspace(key='theta', start=0.1, stop=max_angle / np.pi, length=num_points)
     _results = sampler.run_sweep(circuit, params=sweep, repetitions=repetitions)
 
 
 def test_aqt_sampler_ms():
     repetitions = 1000
     num_qubits = 4
-    device, qubits = get_aqt_device(num_qubits)
+    _, qubits = get_aqt_device(num_qubits)
     sampler = AQTSamplerLocalSimulator()
-    circuit = cirq.Circuit(device=device)
+    circuit = cirq.Circuit(cirq.Z.on_each(*qubits), cirq.Z.on_each(*qubits))
     for _dummy in range(9):
         circuit.append(cirq.XX(qubits[0], qubits[1]) ** 0.5)
     circuit.append(cirq.Z(qubits[0]) ** 0.5)

cirq-aqt/cirq_aqt/aqt_simulator_test.py

@@ -30,8 +30,8 @@ def test_simulator_no_circ():
 def test_ms_crosstalk_n_noise():
     num_qubits = 4
     noise_mod = AQTNoiseModel()
-    device, qubits = get_aqt_device(num_qubits)
-    circuit = cirq.Circuit(device=device)
+    _, qubits = get_aqt_device(num_qubits)
+    circuit = cirq.Circuit()
     circuit.append(cirq.XX(qubits[1], qubits[2]) ** 0.5)
     for moment in circuit.moments:
         noisy_moment = noise_mod.noisy_moment(moment, qubits)
@@ -49,8 +49,8 @@ def test_ms_crosstalk_n_noise():
 def test_x_crosstalk_n_noise():
     num_qubits = 4
     noise_mod = AQTNoiseModel()
-    device, qubits = get_aqt_device(num_qubits)
-    circuit = cirq.Circuit(device=device)
+    _, qubits = get_aqt_device(num_qubits)
+    circuit = cirq.Circuit()
     circuit.append(cirq.Y(qubits[1]) ** 0.5)
     circuit.append(cirq.Z(qubits[1]) ** 0.5)
     circuit.append(cirq.X(qubits[1]) ** 0.5)