PauliExpBoxes.hpp

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// Copyright Quantinuum
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
 
#pragma once
 
#include "Boxes.hpp"
#include "tket/Diagonalisation/PauliPartition.hpp"
#include "tket/Transformations/PauliOptimisation.hpp"
 
namespace tket {
 
class PauliExpBoxInvalidity : public std::logic_error {
 public:
  explicit PauliExpBoxInvalidity(const std::string &message)
      : std::logic_error(message) {}
};
 
class PauliExpBox : public Box {
 public:
  PauliExpBox(
      const SymPauliTensor &paulis,
      CXConfigType cx_config_type = CXConfigType::Tree);
 
  PauliExpBox();
 
  PauliExpBox(const PauliExpBox &other);
 
  ~PauliExpBox() override = default;
 
  bool is_clifford() const override;
 
  SymSet free_symbols() const override;
 
  bool is_equal(const Op &op_other) const override;
 
  std::vector<Pauli> get_paulis() const { return paulis_.string; }
 
  Expr get_phase() const { return paulis_.coeff; }
 
  CXConfigType get_cx_config() const { return cx_config_; }
 
  Op_ptr dagger() const override;
 
  Op_ptr transpose() const override;
 
  Op_ptr symbol_substitution(
      const SymEngine::map_basic_basic &sub_map) const override;
 
  static Op_ptr from_json(const nlohmann::json &j);
 
  static nlohmann::json to_json(const Op_ptr &op);
 
 protected:
  void generate_circuit() const override;
 
 private:
  SymPauliTensor paulis_;
  CXConfigType cx_config_;
};
 
class PauliExpPairBox : public Box {
 public:
  PauliExpPairBox(
      const SymPauliTensor &paulis0, const SymPauliTensor &paulis1,
      CXConfigType cx_config_type = CXConfigType::Tree);
 
  PauliExpPairBox();
 
  PauliExpPairBox(const PauliExpPairBox &other);
 
  ~PauliExpPairBox() override {}
 
  bool is_clifford() const override;
 
  SymSet free_symbols() const override;
 
  bool is_equal(const Op &op_other) const override;
 
  std::pair<std::vector<Pauli>, std::vector<Pauli>> get_paulis_pair() const {
    return std::make_pair(paulis0_.string, paulis1_.string);
  }
 
  std::pair<Expr, Expr> get_phase_pair() const {
    return std::make_pair(paulis0_.coeff, paulis1_.coeff);
  }
 
  CXConfigType get_cx_config() const { return cx_config_; }
 
  Op_ptr dagger() const override;
 
  Op_ptr transpose() const override;
 
  Op_ptr symbol_substitution(
      const SymEngine::map_basic_basic &sub_map) const override;
 
  static Op_ptr from_json(const nlohmann::json &j);
 
  static nlohmann::json to_json(const Op_ptr &op);
 
 protected:
  void generate_circuit() const override;
 
 private:
  SymPauliTensor paulis0_;
  SymPauliTensor paulis1_;
  CXConfigType cx_config_;
};
 
class PauliExpCommutingSetBox : public Box {
 public:
  PauliExpCommutingSetBox(
      const std::vector<SymPauliTensor> &pauli_gadgets,
      CXConfigType cx_config_type = CXConfigType::Tree);
 
  PauliExpCommutingSetBox();
 
  PauliExpCommutingSetBox(const PauliExpCommutingSetBox &other);
 
  ~PauliExpCommutingSetBox() override {}
 
  bool paulis_commute() const;
 
  bool is_clifford() const override;
 
  SymSet free_symbols() const override;
 
  bool is_equal(const Op &op_other) const override;
 
  auto get_pauli_gadgets() const { return pauli_gadgets_; }
 
  auto get_cx_config() const { return cx_config_; }
 
  Op_ptr dagger() const override;
 
  Op_ptr transpose() const override;
 
  Op_ptr symbol_substitution(
      const SymEngine::map_basic_basic &sub_map) const override;
 
  static Op_ptr from_json(const nlohmann::json &j);
 
  static nlohmann::json to_json(const Op_ptr &op);
 
 protected:
  void generate_circuit() const override;
 
 private:
  std::vector<SymPauliTensor> pauli_gadgets_;
  CXConfigType cx_config_;
};
 
class TermSequenceBox : public Box {
 public:
  TermSequenceBox(
      const std::vector<SymPauliTensor> &pauli_gadgets,
      Transforms::PauliSynthStrat synth_strategy =
          Transforms::PauliSynthStrat::Sets,
      PauliPartitionStrat partition_strategy =
          PauliPartitionStrat::CommutingSets,
      GraphColourMethod graph_colouring = GraphColourMethod::Lazy,
      CXConfigType cx_configuration = CXConfigType::Tree,
      double depth_weight = 0.3);
 
  TermSequenceBox();
 
  TermSequenceBox(const TermSequenceBox &other);
 
  ~TermSequenceBox() override {}
 
  bool is_clifford() const override;
 
  SymSet free_symbols() const override;
 
  bool is_equal(const Op &op_other) const override;
 
  Transforms::PauliSynthStrat get_synth_strategy() const;
 
  PauliPartitionStrat get_partition_strategy() const;
 
  GraphColourMethod get_graph_colouring() const;
 
  std::vector<SymPauliTensor> get_pauli_gadgets() const;
 
  CXConfigType get_cx_config() const;
 
  double get_depth_weight() const;
 
  Op_ptr dagger() const override;
 
  Op_ptr transpose() const override;
 
  Op_ptr symbol_substitution(
      const SymEngine::map_basic_basic &sub_map) const override;
 
  static Op_ptr from_json(const nlohmann::json &j);
 
  static nlohmann::json to_json(const Op_ptr &op);
 
 protected:
  void generate_circuit() const override;
 
 private:
  std::vector<SymPauliTensor> pauli_gadgets_;
  Transforms::PauliSynthStrat synth_strategy_;
  PauliPartitionStrat partition_strategy_;
  GraphColourMethod graph_colouring_;
  CXConfigType cx_configuration_;
  double depth_weight_;
};
 
void append_single_pauli_gadget_as_pauli_exp_box(
    Circuit &circ, const SpSymPauliTensor &pauli, CXConfigType cx_config);
 
void append_pauli_gadget_pair_as_box(
    Circuit &circ, const SpSymPauliTensor &pauli0,
    const SpSymPauliTensor &pauli1, CXConfigType cx_config);
 
void append_commuting_pauli_gadget_set_as_box(
    Circuit &circ, const std::list<SpSymPauliTensor> &gadgets,
    CXConfigType cx_config);
 
}  // namespace tket