Merge pull request #157 from dlyongemallo/fix_ry

Fix direction of qasm `ry` rotation and add `y` gate.

pyzx/circuit/gates.py

@@ -456,7 +456,7 @@ def __str__(self) -> str:
         return 'QRot["exp(-i%Y)",{!s}]({!s})'.format(math.pi*self.phase/2,self.target)
 
     def to_basic_gates(self):
-        return [ZPhase(self.target, Fraction(1,2)), XPhase(self.target, self.phase), ZPhase(self.target, -Fraction(1,2))]
+        return [ZPhase(self.target, Fraction(1,2)), XPhase(self.target, -self.phase), ZPhase(self.target, -Fraction(1,2))]
 
     def to_graph(self, g, q_mapper, c_mapper):
         for gate in self.to_basic_gates():
@@ -465,6 +465,15 @@ def to_graph(self, g, q_mapper, c_mapper):
     def tcount(self):
         return 1 if self.phase.denominator > 2 else 0
 
+class Y(YPhase):
+    name = 'Y'
+    qasm_name = 'y'
+    qc_name = 'Y'
+    quipper_name = 'Y'
+    print_phase = False
+    def __init__(self, target: int) -> None:
+        super().__init__(target, phase = Fraction(1,1))
+
 class NOT(XPhase):
     name = 'NOT'
     qasm_name = 'x'
@@ -990,6 +999,7 @@ def to_graph(self, g, q_mapper, c_mapper):
 
 qasm_gate_table: Dict[str, Type[Gate]] = {
     "x": NOT,
+    "y": Y,
     "z": Z,
     "s": S,
     "t": T,

pyzx/circuit/qasmparser.py

@@ -169,7 +169,7 @@ def parse_command(self, c: str, registers: Dict[str,Tuple[int,int]]) -> List[Gat
                 for g in circ.gates:
                     gates.append(g.reposition(argset))
                 continue
-            if name in ('x', 'z', 's', 't', 'h', 'sdg', 'tdg'):
+            if name in ('x', 'y', 'z', 's', 't', 'h', 'sdg', 'tdg'):
                 if name in ('sdg', 'tdg'):
                     g = qasm_gate_table[name](argset[0],adjoint=True) # type: ignore # mypy can't handle -
                 else: g = qasm_gate_table[name](argset[0]) # type: ignore # - Gate subclasses with different numbers of parameters

tests/test_ry.py

@@ -54,5 +54,5 @@ def test_load_qasm_from_file(self):
     def test_ry_preserves_graph_semantics(self):
         g = self.c.to_graph()
         t = tensor_to_matrix(tensorfy(g, False), 1, 1)
-        expected_t = np.asarray([[np.cos(np.pi/8), np.sin(np.pi/8)], [-np.sin(np.pi/8), np.cos(np.pi/8)]])
+        expected_t = np.asarray([[np.cos(np.pi/8), -np.sin(np.pi/8)], [np.sin(np.pi/8), np.cos(np.pi/8)]])
         self.assertTrue(compare_tensors(t, expected_t, False))