Merge pull request #1201 from CQCL/bugfix/revert-refactor

Revert "Unitary Synthesis of ChoiMixTableau for Diagonalisation (#941)"

pytket/conanfile.py

@@ -32,7 +32,7 @@ def package(self):
         cmake.install()
 
     def requirements(self):
-        self.requires("tket/1.2.81@tket/stable")
+        self.requires("tket/1.2.82@tket/stable")
         self.requires("tklog/0.3.3@tket/stable")
         self.requires("tkrng/0.3.3@tket/stable")
         self.requires("tkassert/0.3.4@tket/stable")

pytket/docs/changelog.rst

@@ -24,6 +24,8 @@ Fixes:
 * For `Circuit` with no 2-qubit gates, `NoiseAwarePlacement` now assigns `Qubit` to `Node` in `Architecture`
   with lowest reported error rates.
 * Fix invalid registers returned by ``Circuit.q_registers`` and ``Circuit.c_registers``.
+* Fix regression (introduced in 1.22.0) in compilation performance with certain
+  sequences of passes.
 
 
 1.22.0 (November 2023)

pytket/tests/ansatz_sequence_test.py

@@ -88,9 +88,9 @@ def test_nontrivial_sequence() -> None:
             GraphColourMethod.Exhaustive: (3, 28, 20, 19),
         },
         PauliPartitionStrat.NonConflictingSets: {
-            GraphColourMethod.LargestFirst: (6, 28, 28, 26),
-            GraphColourMethod.Lazy: (6, 28, 28, 28),
-            GraphColourMethod.Exhaustive: (6, 28, 28, 28),
+            GraphColourMethod.LargestFirst: (6, 28, 28, 28),
+            GraphColourMethod.Lazy: (6, 28, 28, 26),
+            GraphColourMethod.Exhaustive: (6, 28, 28, 26),
         },
     }
 

tket/CMakeLists.txt

@@ -224,6 +224,7 @@ target_sources(tket
         src/ZX/MBQCRewrites.cpp
         src/ZX/ZXRWSequences.cpp
         src/Converters/ChoiMixTableauConverters.cpp
+        src/Converters/PauliGadget.cpp
         src/Converters/PauliGraphConverters.cpp
         src/Converters/Gauss.cpp
         src/Converters/PhasePoly.cpp
@@ -376,6 +377,7 @@ target_sources(tket
         include/tket/ZX/ZXGenerator.hpp
         include/tket/Converters/Converters.hpp
         include/tket/Converters/Gauss.hpp
+        include/tket/Converters/PauliGadget.hpp
         include/tket/Converters/PhasePoly.hpp
         include/tket/Converters/UnitaryTableauBox.hpp
         include/tket/Placement/NeighbourPlacements.hpp

tket/conanfile.py

@@ -23,7 +23,7 @@
 
 class TketConan(ConanFile):
     name = "tket"
-    version = "1.2.81"
+    version = "1.2.82"
     package_type = "library"
     license = "Apache 2"
     homepage = "https://github.com/CQCL/tket"

tket/include/tket/Circuit/CircUtils.hpp

@@ -111,13 +111,13 @@ std::pair<Circuit, Complex> decompose_2cx_DV(const Eigen::Matrix4cd& U);
  * Construct a phase gadget
  *
  * @param n_qubits number of qubits
- * @param angle phase parameter
+ * @param t phase parameter
  * @param cx_config CX configuration
  *
  * @return phase gadget implementation wrapped in a ConjugationBox
  */
 Circuit phase_gadget(
-    unsigned n_qubits, const Expr& angle,
+    unsigned n_qubits, const Expr& t,
     CXConfigType cx_config = CXConfigType::Snake);
 
 /**
@@ -127,29 +127,13 @@ Circuit phase_gadget(
  * \f$ e^{-\frac12 i \pi t \sigma_0 \otimes \sigma_1 \otimes \cdots} \f$
  * where \f$ \sigma_i \in \{I,X,Y,Z\} \f$ are the Pauli operators.
  *
- * @param paulis Pauli operators; coefficient gives rotation angle in half-turns
+ * @param paulis Pauli operators
+ * @param t angle in half-turns
  * @param cx_config CX configuration
  * @return Pauli gadget implementation wrapped in a ConjugationBox
  */
 Circuit pauli_gadget(
-    SpSymPauliTensor paulis, CXConfigType cx_config = CXConfigType::Snake);
-
-/**
- * Construct a circuit realising a pair of Pauli gadgets with the fewest
- * two-qubit gates.
- *
- * The returned circuit implements the unitary e^{-i pi angle1 paulis1 / 2}
- * e^{-i pi angle0 paulis0 / 2}, i.e. a gadget of angle0 about paulis0 followed
- * by a gadget of angle1 about paulis1.
- *
- * @param paulis0 Pauli operators for first gadget; coefficient gives rotation
- * angle in half-turns
- * @param paulis1 Pauli operators for second gadget; coefficient gives rotation
- * angle in half-turns
- * @param cx_config CX configuration
- */
-Circuit pauli_gadget_pair(
-    SpSymPauliTensor paulis0, SpSymPauliTensor paulis1,
+    const std::vector<Pauli>& paulis, const Expr& t,
     CXConfigType cx_config = CXConfigType::Snake);
 
 /**

tket/include/tket/Circuit/PauliExpBoxes.hpp

@@ -202,46 +202,4 @@ class PauliExpCommutingSetBox : public Box {
   CXConfigType cx_config_;
 };
 
-/**
- * Constructs a PauliExpBox for a single pauli gadget and appends it to a
- * circuit.
- *
- * @param circ The circuit to append the box to
- * @param pauli The pauli operator of the gadget; coefficient gives the rotation
- * angle in half-turns
- * @param cx_config The CX configuration to be used during synthesis
- */
-void append_single_pauli_gadget_as_pauli_exp_box(
-    Circuit &circ, const SpSymPauliTensor &pauli, CXConfigType cx_config);
-
-/**
- * Constructs a PauliExpPairBox for a pair of pauli gadgets and appends it to a
- * circuit. The pauli gadgets may or may not commute, so the ordering matters.
- *
- * @param circ The circuit to append the box to
- * @param pauli0 The pauli operator of the first gadget; coefficient gives the
- * rotation angle in half-turns
- * @param pauli1 The pauli operator of the second gadget; coefficient gives the
- * rotation angle in half-turns
- * @param cx_config The CX configuration to be used during synthesis
- */
-void append_pauli_gadget_pair_as_box(
-    Circuit &circ, const SpSymPauliTensor &pauli0,
-    const SpSymPauliTensor &pauli1, CXConfigType cx_config);
-
-/**
- * Constructs a PauliExpCommutingSetBox for a set of mutually commuting pauli
- * gadgets and appends it to a circuit. As the pauli gadgets all commute, the
- * ordering does not matter semantically, but may yield different synthesised
- * circuits.
- *
- * @param circ The circuit to append the box to
- * @param gadgets Description of the pauli gadgets; coefficients give the
- * rotation angles in half-turns
- * @param cx_config The CX configuration to be used during synthesis
- */
-void append_commuting_pauli_gadget_set_as_box(
-    Circuit &circ, const std::list<SpSymPauliTensor> &gadgets,
-    CXConfigType cx_config);
-
 }  // namespace tket

tket/include/tket/Clifford/ChoiMixTableau.hpp

@@ -45,8 +45,7 @@ class ChoiMixTableau {
    * When mapped to a sparse readable representation, independent
    * SpPauliStabiliser objects are used for each segment, so we no longer expect
    * their individual phases to be +-1, instead only requiring this on their
-   * product. get_row() will automatically transpose the input segment term so
-   * it is presented as RxS s.t. SCR = C.
+   * product.
    *
    * Columns of the tableau are indexed by pair of Qubit id and a tag to
    * distinguish input vs output. Rows are not maintained in any particular
@@ -94,7 +93,6 @@ class ChoiMixTableau {
    * Construct a tableau directly from its rows.
    * Each row is represented as a product of SpPauliStabilisers where the first
    * is over the input qubits and the second is over the outputs.
-   * A row RxS is a pair s.t. SCR = C
    */
   explicit ChoiMixTableau(const std::list<row_tensor_t>& rows);
   /**
@@ -124,23 +122,13 @@ class ChoiMixTableau {
    * Get the number of boundaries representing outputs from the process.
    */
   unsigned get_n_outputs() const;
-  /**
-   * Get all qubit names present in the input segment.
-   */
-  qubit_vector_t input_qubits() const;
-  /**
-   * Get all qubit names present in the output segment.
-   */
-  qubit_vector_t output_qubits() const;
 
   /**
-   * Read off a row as a Pauli string.
-   * Returns a pair of Pauli strings RxS such that SCR = C
+   * Read off a row as a Pauli string
    */
   row_tensor_t get_row(unsigned i) const;
   /**
-   * Combine rows into a single row.
-   * Returns a pair of Pauli strings RxS such that SCR = C
+   * Combine rows into a single row
    */
   row_tensor_t get_row_product(const std::vector<unsigned>& rows) const;
 
@@ -154,10 +142,7 @@ class ChoiMixTableau {
    * outputs.
    */
   void apply_S(const Qubit& qb, TableauSegment seg = TableauSegment::Output);
-  void apply_Z(const Qubit& qb, TableauSegment seg = TableauSegment::Output);
   void apply_V(const Qubit& qb, TableauSegment seg = TableauSegment::Output);
-  void apply_X(const Qubit& qb, TableauSegment seg = TableauSegment::Output);
-  void apply_H(const Qubit& qb, TableauSegment seg = TableauSegment::Output);
   void apply_CX(
       const Qubit& control, const Qubit& target,
       TableauSegment seg = TableauSegment::Output);

tket/include/tket/Clifford/SymplecticTableau.hpp

@@ -20,6 +20,12 @@
 
 namespace tket {
 
+// Forward declare friend classes for converters
+class ChoiMixTableau;
+class UnitaryTableau;
+class UnitaryRevTableau;
+class Circuit;
+
 /**
  * Boolean encoding of Pauli
  * <x, z> = <false, false> ==> I
@@ -130,13 +136,10 @@ class SymplecticTableau {
   void row_mult(unsigned ra, unsigned rw, Complex coeff = 1.);
 
   /**
-   * Applies a chosen gate to the given qubit(s)
+   * Applies an S/V/CX gate to the given qubit(s)
    */
   void apply_S(unsigned qb);
-  void apply_Z(unsigned qb);
   void apply_V(unsigned qb);
-  void apply_X(unsigned qb);
-  void apply_H(unsigned qb);
   void apply_CX(unsigned qc, unsigned qt);
   void apply_gate(OpType type, const std::vector<unsigned> &qbs);
 
@@ -170,19 +173,29 @@ class SymplecticTableau {
    */
   void gaussian_form();
 
+ private:
+  /**
+   * Number of rows
+   */
+  unsigned n_rows_;
+
+  /**
+   * Number of qubits in each row
+   */
+  unsigned n_qubits_;
+
   /**
    * Tableau contents
    */
-  MatrixXb xmat;
-  MatrixXb zmat;
-  VectorXb phase;
+  MatrixXb xmat_;
+  MatrixXb zmat_;
+  VectorXb phase_;
 
   /**
    * Complex conjugate of the state by conjugating rows
    */
   SymplecticTableau conjugate() const;
 
- private:
   /**
    * Helper methods for manipulating the tableau when applying gates
    */
@@ -193,6 +206,18 @@ class SymplecticTableau {
   void col_mult(
       const MatrixXb::ColXpr &a, const MatrixXb::ColXpr &b, bool flip,
       MatrixXb::ColXpr &w, VectorXb &pw);
+
+  friend class UnitaryTableau;
+  friend class ChoiMixTableau;
+  friend Circuit unitary_tableau_to_circuit(const UnitaryTableau &tab);
+  friend std::pair<Circuit, unit_map_t> cm_tableau_to_circuit(
+      const ChoiMixTableau &tab);
+  friend std::ostream &operator<<(std::ostream &os, const UnitaryTableau &tab);
+  friend std::ostream &operator<<(
+      std::ostream &os, const UnitaryRevTableau &tab);
+
+  friend void to_json(nlohmann::json &j, const SymplecticTableau &tab);
+  friend void from_json(const nlohmann::json &j, SymplecticTableau &tab);
 };
 
 JSON_DECL(SymplecticTableau)

tket/include/tket/Clifford/UnitaryTableau.hpp

@@ -101,14 +101,8 @@ class UnitaryTableau {
    */
   void apply_S_at_front(const Qubit& qb);
   void apply_S_at_end(const Qubit& qb);
-  void apply_Z_at_front(const Qubit& qb);
-  void apply_Z_at_end(const Qubit& qb);
   void apply_V_at_front(const Qubit& qb);
   void apply_V_at_end(const Qubit& qb);
-  void apply_X_at_front(const Qubit& qb);
-  void apply_X_at_end(const Qubit& qb);
-  void apply_H_at_front(const Qubit& qb);
-  void apply_H_at_end(const Qubit& qb);
   void apply_CX_at_front(const Qubit& control, const Qubit& target);
   void apply_CX_at_end(const Qubit& control, const Qubit& target);
   void apply_gate_at_front(OpType type, const qubit_vector_t& qbs);
@@ -242,14 +236,8 @@ class UnitaryRevTableau {
    */
   void apply_S_at_front(const Qubit& qb);
   void apply_S_at_end(const Qubit& qb);
-  void apply_Z_at_front(const Qubit& qb);
-  void apply_Z_at_end(const Qubit& qb);
   void apply_V_at_front(const Qubit& qb);
   void apply_V_at_end(const Qubit& qb);
-  void apply_X_at_front(const Qubit& qb);
-  void apply_X_at_end(const Qubit& qb);
-  void apply_H_at_front(const Qubit& qb);
-  void apply_H_at_end(const Qubit& qb);
   void apply_CX_at_front(const Qubit& control, const Qubit& target);
   void apply_CX_at_end(const Qubit& control, const Qubit& target);
   void apply_gate_at_front(OpType type, const qubit_vector_t& qbs);