Add cnot gate to the models (#109)

surface_sim/models/library.py

@@ -80,6 +80,20 @@ def cphase(self, qubits: Sequence[str]) -> Circuit:
             circ.append(CircuitInstruction("DEPOLARIZE2", ind_pair, [prob]))
         return circ
 
+    def cnot(self, qubits: Sequence[str]) -> Circuit:
+        if len(qubits) % 2 != 0:
+            raise ValueError("Expected and even number of qubits.")
+
+        inds = self.get_inds(qubits)
+        circ = Circuit()
+
+        circ.append(CircuitInstruction("CNOT", inds))
+
+        for qubit_pair, ind_pair in zip(grouper(qubits, 2), grouper(inds, 2)):
+            prob = self.param("cz_error_prob", *qubit_pair)
+            circ.append(CircuitInstruction("DEPOLARIZE2", ind_pair, [prob]))
+        return circ
+
     def measure(self, qubits: Iterable[str]) -> Circuit:
         inds = self.get_inds(qubits)
         circ = Circuit()
@@ -232,6 +246,26 @@ def cphase(self, qubits: Sequence[str]) -> Circuit:
             circ.append(CircuitInstruction("PAULI_CHANNEL_2", ind_pair, probs))
         return circ
 
+    def cnot(self, qubits: Sequence[str]) -> Circuit:
+        if len(qubits) % 2 != 0:
+            raise ValueError("Expected and even number of qubits.")
+
+        inds = self.get_inds(qubits)
+        circ = Circuit()
+
+        circ.append(CircuitInstruction("CNOT", inds))
+
+        for qubit_pair, ind_pair in zip(grouper(qubits, 2), grouper(inds, 2)):
+            prob = self.param("cz_error_prob", *qubit_pair)
+            prefactors = biased_prefactors(
+                biased_pauli=self.param("biased_pauli", *qubit_pair),
+                biased_factor=self.param("biased_factor", *qubit_pair),
+                num_qubits=2,
+            )
+            probs = prob * prefactors
+            circ.append(CircuitInstruction("PAULI_CHANNEL_2", ind_pair, probs))
+        return circ
+
     def measure(self, qubits: Iterable[str]) -> Circuit:
         inds = self.get_inds(qubits)
         circ = Circuit()
@@ -339,6 +373,9 @@ def s_dag_gate(self, qubits: Iterable[str]) -> Circuit:
     def cphase(self, qubits: Iterable[str]) -> Circuit:
         return self.generic_op("CZ", qubits)
 
+    def cnot(self, qubits: Iterable[str]) -> Circuit:
+        return self.generic_op("CNOT", qubits)
+
     def measure(self, qubits: Iterable[str]) -> Circuit:
         circ = Circuit()
         name = "M"
@@ -468,6 +505,20 @@ def cphase(self, qubits: Sequence[str]) -> Circuit:
             circ.append(CircuitInstruction("DEPOLARIZE2", ind_pair, [prob]))
         return circ
 
+    def cnot(self, qubits: Sequence[str]) -> Circuit:
+        if len(qubits) % 2 != 0:
+            raise ValueError("Expected and even number of qubits.")
+
+        inds = self.get_inds(qubits)
+        circ = Circuit()
+
+        circ.append(CircuitInstruction("CNOT", inds))
+
+        for qubit_pair, ind_pair in zip(grouper(qubits, 2), grouper(inds, 2)):
+            prob = self.param("cz_error_prob", *qubit_pair)
+            circ.append(CircuitInstruction("DEPOLARIZE2", ind_pair, [prob]))
+        return circ
+
     def measure(self, qubits: Iterable[str]) -> Circuit:
         inds = self.get_inds(qubits)
         circ = Circuit()
@@ -573,6 +624,11 @@ def cphase(self, qubits: Sequence[str]) -> Circuit:
         circ.append(CircuitInstruction("CZ", self.get_inds(qubits)))
         return circ
 
+    def cnot(self, qubits: Sequence[str]) -> Circuit:
+        circ = Circuit()
+        circ.append(CircuitInstruction("CNOT", self.get_inds(qubits)))
+        return circ
+
     def measure(self, qubits: Iterable[str]) -> Circuit:
         circ = Circuit()
         for qubit in qubits:

surface_sim/models/model.py

@@ -135,6 +135,9 @@ def s_gate(self, qubits: Iterable[str]) -> Circuit:
     def s_dag_gate(self, qubits: Iterable[str]) -> Circuit:
         raise NotImplementedError
 
+    def cnot(self, qubits: Sequence[str]) -> Circuit:
+        raise NotImplementedError
+
     def cphase(self, qubits: Sequence[str]) -> Circuit:
         raise NotImplementedError
 

tests/models/test_library.py

@@ -16,6 +16,7 @@
         "Z": 1,
         "H": 1,
         "CZ": 1,
+        "CNOT": 1,
         "M": 1,
         "R": 1,
     },
@@ -59,6 +60,12 @@ def test_NoiselessModel():
     ops = [o.name for o in model.cphase(["D1", "D2"])]
     assert ops == ["CZ"]
 
+    ops = [o.name for o in model.cnot(["D1", "D2"])]
+    assert ops == ["CX"]
+
+    ops = [o.name for o in model.cnot(["D1", "D2"])]
+    assert ops == ["CX"]
+
     ops = [o.name for o in model.measure(["D1"])]
     assert ops == ["M"]
 
@@ -87,6 +94,12 @@ def test_PhenomenologicalNoiseModel():
     ops = [o.name for o in model.cphase(["D1", "D2"])]
     assert ops == ["CZ"]
 
+    ops = [o.name for o in model.cnot(["D1", "D2"])]
+    assert ops == ["CX"]
+
+    ops = [o.name for o in model.cnot(["D1", "D2"])]
+    assert ops == ["CX"]
+
     ops = [o.name for o in model.measure(["D1"])]
     assert "M" in ops
     assert set(NOISE_GATES + ["M"]) >= set(ops)
@@ -121,6 +134,9 @@ def test_IncomingNoiseModel():
     ops = [o.name for o in model.cphase(["D1", "D2"])]
     assert ops == ["CZ"]
 
+    ops = [o.name for o in model.cnot(["D1", "D2"])]
+    assert ops == ["CX"]
+
     ops = [o.name for o in model.measure(["D1"])]
     assert ops == ["M"]
 
@@ -161,6 +177,11 @@ def test_DecoherentNoiseModel():
     assert set(NOISE_GATES + ["CZ"]) >= set(ops)
     assert len(ops) > 1
 
+    ops = [o.name for o in model.cnot(["D1", "D2"])]
+    assert "CX" in ops
+    assert set(NOISE_GATES + ["CX"]) >= set(ops)
+    assert len(ops) > 1
+
     ops = [o.name for o in model.measure(["D1"])]
     assert "M" in ops
     assert set(NOISE_GATES + ["M"]) >= set(ops)
@@ -205,6 +226,11 @@ def test_ExperimentalNoiseModel():
     assert set(NOISE_GATES + ["CZ"]) >= set(ops)
     assert len(ops) > 1
 
+    ops = [o.name for o in model.cnot(["D1", "D2"])]
+    assert "CX" in ops
+    assert set(NOISE_GATES + ["CX"]) >= set(ops)
+    assert len(ops) > 1
+
     ops = [o.name for o in model.measure(["D1"])]
     assert "M" in ops
     assert set(NOISE_GATES + ["M"]) >= set(ops)
@@ -249,6 +275,11 @@ def test_CircuitNoiseModel():
     assert set(NOISE_GATES + ["CZ"]) >= set(ops)
     assert len(ops) > 1
 
+    ops = [o.name for o in model.cnot(["D1", "D2"])]
+    assert "CX" in ops
+    assert set(NOISE_GATES + ["CX"]) >= set(ops)
+    assert len(ops) > 1
+
     ops = [o.name for o in model.measure(["D1"])]
     assert "M" in ops
     assert set(NOISE_GATES + ["M"]) >= set(ops)