fix ry gate for stabilizer (Qiskit#2001)

Co-authored-by: Hiroshi Horii <hhorii@users.noreply.github.com>
doichanj · Nov 21, 2023 · 68b89e7 · 68b89e7
1 parent 1c7d241
commit 68b89e7
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Showing 2 changed files with 6 additions and 4 deletions.
diff --git a/releasenotes/notes/fix_stabilizer_ry_gate-07538d8a2462c09d.yaml b/releasenotes/notes/fix_stabilizer_ry_gate-07538d8a2462c09d.yaml
@@ -0,0 +1,4 @@
+---
+fixes:
+  - |
+    fixed ry gate for stabilizer method, PI/2 and PI3/2 was inverted
diff --git a/src/simulators/stabilizer/stabilizer_state.hpp b/src/simulators/stabilizer/stabilizer_state.hpp
@@ -417,16 +417,14 @@ void State::apply_gate(const Operations::Op &op) {
   case Gates::ry:
     pi2 = (int_t)std::round(std::real(op.params[0]) * 2.0 / M_PI) & 3;
     if (pi2 == 1) {
-      // HX
-      BaseState::qreg_.append_x(op.qubits[0]);
       BaseState::qreg_.append_h(op.qubits[0]);
+      BaseState::qreg_.append_x(op.qubits[0]);
     } else if (pi2 == 2) {
       // Y
       BaseState::qreg_.append_y(op.qubits[0]);
     } else if (pi2 == 3) {
-      // Hdg
-      BaseState::qreg_.append_h(op.qubits[0]);
       BaseState::qreg_.append_x(op.qubits[0]);
+      BaseState::qreg_.append_h(op.qubits[0]);
     }
     break;
   case Gates::rz: