Support for Neutral Atom State Preparation

include/mqt-core/datastructures/Layer.hpp

@@ -125,7 +125,7 @@ class Layer final {
 
 protected:
   ExecutableSet executableSet;
-  auto constructDAG(const QuantumComputation& qc) -> void;
+  auto constructDAG(const QuantumComputation& qc, bool commutable) -> void;
 
 public:
   Layer() = default;
@@ -134,7 +134,21 @@ class Layer final {
   Layer& operator=(const Layer&) = default;
   Layer& operator=(Layer&&) = default;
   ~Layer() = default;
-  explicit Layer(const QuantumComputation& qc) { constructDAG(qc); }
+  /**
+   * @brief Constructs a new layer from the given quantum circuit.
+   * @details The layer contains all gates that are currently executable in a
+   * set of executable gates. When a gate is executed, this can enable other
+   * gates that are added to the set of executable sets then, or disable gates
+   * that are removed from the set of executable gates. The commutable flag can
+   * be used to specify whether commutation rules should be considered.
+   *
+   * @param qc         quantum circuit
+   * @param commutable true if commutation rules should be considered, false
+   * otherwise (default: true)
+   */
+  explicit Layer(const QuantumComputation& qc, bool commutable = true) {
+    constructDAG(qc, commutable);
+  }
   [[nodiscard]] auto getExecutableSet() const -> const ExecutableSet& {
     return executableSet;
   }

src/datastructures/Layer.cpp

@@ -13,7 +13,8 @@
 
 namespace qc {
 
-auto Layer::constructDAG(const QuantumComputation& qc) -> void {
+auto Layer::constructDAG(const QuantumComputation& qc,
+                         const bool commutable) -> void {
   const auto nQubits = qc.getNqubits();
   // For a pair of self-canceling operations like two consecutive X operations
   // or RY rotations with opposite angles the first operations is a
@@ -104,7 +105,8 @@ auto Layer::constructDAG(const QuantumComputation& qc) -> void {
           // that would not commute because redundant operations in a group
           // cause problems later on, e.g., when generating interaction graphs
           if (!currentGroup[qubit].empty() &&
-              (!(currentGroup[qubit][0]->getOperation())
+              (!commutable ||
+               !(currentGroup[qubit][0]->getOperation())
                     ->commutesAtQubit(*current->getOperation(), qubit) ||
                std::find_if(
                    currentGroup[qubit].cbegin(), currentGroup[qubit].cend(),
@@ -145,8 +147,9 @@ auto Layer::constructDAG(const QuantumComputation& qc) -> void {
       // check whether the current operation commutes with the current
       // group members
       if (!currentGroup[qubit].empty() and
-          !(currentGroup[qubit][0]->getOperation())
-               ->commutesAtQubit(*current->getOperation(), qubit)) {
+          (!commutable or
+           !(currentGroup[qubit][0]->getOperation())
+                ->commutesAtQubit(*current->getOperation(), qubit))) {
         // here: the current operation does not commute with the current
         // group members and is not the inverse of the lookahead
         // --> start a new group

test/datastructures/test_layer.cpp

@@ -9,6 +9,7 @@
 #include <memory>
 #include <stdexcept>
 #include <tuple>
+#include <unordered_set>
 #include <vector>
 
 namespace qc {
@@ -86,6 +87,31 @@ TEST(Layer, ExecutableSet2) {
   EXPECT_EQ(layer.getExecutableSet().size(), 10);
 }
 
+TEST(Layer, ExecutableSetNotCommutable) {
+  QuantumComputation qc{};
+  qc = QuantumComputation(8);
+  qc.cz(1, 7);
+  qc.cz(2, 4);
+  qc.cz(5, 6);
+  qc.cz(1, 5);
+  qc.cz(6, 7);
+  qc.cz(2, 3);
+  qc.cz(1, 3);
+  qc.cz(4, 6);
+  qc.cz(2, 5);
+  const Layer layer(qc, false);
+  EXPECT_EQ(layer.getExecutableSet().size(), 3);
+  std::unordered_set<const Operation*> actualSet{};
+  for (const auto& u : layer.getExecutableSet()) {
+    actualSet.emplace(u->getOperation());
+  }
+  std::unordered_set<const Operation*> expectedSet{};
+  expectedSet.emplace(qc.at(0).get());
+  expectedSet.emplace(qc.at(1).get());
+  expectedSet.emplace(qc.at(2).get());
+  EXPECT_EQ(actualSet, expectedSet);
+}
+
 TEST(Layer, InteractionGraph) {
   QuantumComputation qc{};
   qc = QuantumComputation(8);