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| 1 | +// Copyright 2022 Xanadu Quantum Technologies Inc. |
| 2 | + |
| 3 | +// Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | +// you may not use this file except in compliance with the License. |
| 5 | +// You may obtain a copy of the License at |
| 6 | + |
| 7 | +// http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | + |
| 9 | +// Unless required by applicable law or agreed to in writing, software |
| 10 | +// distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | +// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | +// See the License for the specific language governing permissions and |
| 13 | +// limitations under the License. |
| 14 | + |
| 15 | +#pragma once |
| 16 | + |
| 17 | +#include <array> |
| 18 | +#include <stdexcept> |
| 19 | +#include <tuple> |
| 20 | +#include <utility> |
| 21 | + |
| 22 | +#include "Exception.hpp" |
| 23 | +#include "Types.h" |
| 24 | +#include "Utils.hpp" |
| 25 | + |
| 26 | +#include "ObservablesLQubit.hpp" |
| 27 | +#include "StateVectorLQubitDynamic.hpp" |
| 28 | + |
| 29 | +namespace { |
| 30 | +using Pennylane::LightningQubit::StateVectorLQubitDynamic; |
| 31 | +using Pennylane::LightningQubit::Observables::HermitianObs; |
| 32 | +using Pennylane::LightningQubit::Observables::NamedObs; |
| 33 | +using Pennylane::LightningQubit::Observables::TensorProdObs; |
| 34 | +using Pennylane::Observables::Observable; |
| 35 | +} // namespace |
| 36 | + |
| 37 | +namespace Catalyst::Runtime::Simulator { |
| 38 | + |
| 39 | +/** |
| 40 | + * @brief The LightningObsManager caches observables of a program at runtime |
| 41 | + * and maps each one to a const unique index (`int64_t`) in the scope |
| 42 | + * of the global context manager. |
| 43 | + */ |
| 44 | +template <typename PrecisionT> class LightningObsManager { |
| 45 | + private: |
| 46 | + using VectorStateT = StateVectorLQubitDynamic<PrecisionT>; |
| 47 | + using ComplexT = typename VectorStateT::ComplexT; |
| 48 | + using ObservablePairType = |
| 49 | + std::pair<std::shared_ptr<Observable<VectorStateT>>, ObsType>; |
| 50 | + std::vector<ObservablePairType> observables_{}; |
| 51 | + |
| 52 | + public: |
| 53 | + LightningObsManager() = default; |
| 54 | + ~LightningObsManager() = default; |
| 55 | + |
| 56 | + LightningObsManager(const LightningObsManager &) = delete; |
| 57 | + LightningObsManager &operator=(const LightningObsManager &) = delete; |
| 58 | + LightningObsManager(LightningObsManager &&) = delete; |
| 59 | + LightningObsManager &operator=(LightningObsManager &&) = delete; |
| 60 | + |
| 61 | + /** |
| 62 | + * @brief A helper function to clear constructed observables in the program. |
| 63 | + */ |
| 64 | + void clear() { observables_.clear(); } |
| 65 | + |
| 66 | + /** |
| 67 | + * @brief Check the validity of observable keys. |
| 68 | + * |
| 69 | + * @param obsKeys The vector of observable keys |
| 70 | + * @return bool |
| 71 | + */ |
| 72 | + [[nodiscard]] auto |
| 73 | + isValidObservables(const std::vector<ObsIdType> &obsKeys) const -> bool { |
| 74 | + return std::all_of(obsKeys.begin(), obsKeys.end(), [this](auto i) { |
| 75 | + return (i >= 0 && static_cast<size_t>(i) < observables_.size()); |
| 76 | + }); |
| 77 | + } |
| 78 | + |
| 79 | + /** |
| 80 | + * @brief Get the constructed observable instance. |
| 81 | + * |
| 82 | + * @param key The observable key |
| 83 | + * @return std::shared_ptr<Observable<VectorStateT>> |
| 84 | + */ |
| 85 | + [[nodiscard]] auto getObservable(ObsIdType key) |
| 86 | + -> std::shared_ptr<Observable<VectorStateT>> { |
| 87 | + RT_FAIL_IF(!isValidObservables({key}), "Invalid observable key"); |
| 88 | + return std::get<0>(observables_[key]); |
| 89 | + } |
| 90 | + |
| 91 | + /** |
| 92 | + * @brief Get the number of observables. |
| 93 | + * |
| 94 | + * @return size_t |
| 95 | + */ |
| 96 | + [[nodiscard]] auto numObservables() const -> size_t { |
| 97 | + return observables_.size(); |
| 98 | + } |
| 99 | + |
| 100 | + /** |
| 101 | + * @brief Create and cache a new NamedObs instance. |
| 102 | + * |
| 103 | + * @param obsId The named observable id of type ObsId |
| 104 | + * @param wires The vector of wires the observable acts on |
| 105 | + * @return ObsIdType |
| 106 | + */ |
| 107 | + [[nodiscard]] auto createNamedObs(ObsId obsId, |
| 108 | + const std::vector<size_t> &wires) |
| 109 | + -> ObsIdType { |
| 110 | + auto &&obs_str = std::string( |
| 111 | + Lightning::lookup_obs<Lightning::simulator_observable_support_size>( |
| 112 | + Lightning::simulator_observable_support, obsId)); |
| 113 | + |
| 114 | + observables_.push_back(std::make_pair( |
| 115 | + std::make_shared<NamedObs<VectorStateT>>(obs_str, wires), |
| 116 | + ObsType::Basic)); |
| 117 | + return static_cast<ObsIdType>(observables_.size() - 1); |
| 118 | + } |
| 119 | + |
| 120 | + /** |
| 121 | + * @brief Create and cache a new HermitianObs instance. |
| 122 | + * |
| 123 | + * @param matrix The row-wise Hermitian matrix |
| 124 | + * @param wires The vector of wires the observable acts on |
| 125 | + * @return ObsIdType |
| 126 | + */ |
| 127 | + [[nodiscard]] auto createHermitianObs(const std::vector<ComplexT> &matrix, |
| 128 | + const std::vector<size_t> &wires) |
| 129 | + -> ObsIdType { |
| 130 | + observables_.push_back( |
| 131 | + std::make_pair(std::make_shared<HermitianObs<VectorStateT>>( |
| 132 | + HermitianObs<VectorStateT>{matrix, wires}), |
| 133 | + ObsType::Basic)); |
| 134 | + |
| 135 | + return static_cast<ObsIdType>(observables_.size() - 1); |
| 136 | + } |
| 137 | + |
| 138 | + /** |
| 139 | + * @brief Create and cache a new TensorProd instance. |
| 140 | + * |
| 141 | + * @param obsKeys The vector of observable keys |
| 142 | + * @return ObsIdType |
| 143 | + */ |
| 144 | + [[nodiscard]] auto |
| 145 | + createTensorProdObs(const std::vector<ObsIdType> &obsKeys) -> ObsIdType { |
| 146 | + const auto key_size = obsKeys.size(); |
| 147 | + const auto obs_size = observables_.size(); |
| 148 | + |
| 149 | + std::vector<std::shared_ptr<Observable<VectorStateT>>> obs_vec; |
| 150 | + obs_vec.reserve(key_size); |
| 151 | + |
| 152 | + for (const auto &key : obsKeys) { |
| 153 | + RT_FAIL_IF(static_cast<size_t>(key) >= obs_size || key < 0, |
| 154 | + "Invalid observable key"); |
| 155 | + |
| 156 | + auto &&[obs, type] = observables_[key]; |
| 157 | + obs_vec.push_back(obs); |
| 158 | + } |
| 159 | + |
| 160 | + observables_.push_back(std::make_pair( |
| 161 | + TensorProdObs<VectorStateT>::create(obs_vec), ObsType::TensorProd)); |
| 162 | + |
| 163 | + return static_cast<ObsIdType>(obs_size); |
| 164 | + } |
| 165 | + |
| 166 | + /** |
| 167 | + * @brief Create and cache a new HamiltonianObs instance. |
| 168 | + * |
| 169 | + * @param coeffs The vector of coefficients |
| 170 | + * @param obsKeys The vector of observable keys |
| 171 | + * @return ObsIdType |
| 172 | + */ |
| 173 | + [[nodiscard]] auto |
| 174 | + createHamiltonianObs( const std::vector<PrecisionT> &coeffs, |
| 175 | + const std::vector<ObsIdType> &obsKeys) -> ObsIdType { |
| 176 | + const auto key_size = obsKeys.size(); |
| 177 | + const auto obs_size = observables_.size(); |
| 178 | + |
| 179 | + RT_FAIL_IF( |
| 180 | + key_size != coeffs.size(), |
| 181 | + "Incompatible list of observables and coefficients; " |
| 182 | + "Number of observables and number of coefficients must be equal"); |
| 183 | + |
| 184 | + std::vector<std::shared_ptr<Observable<VectorStateT>>> obs_vec; |
| 185 | + obs_vec.reserve(key_size); |
| 186 | + |
| 187 | + for (auto key : obsKeys) { |
| 188 | + RT_FAIL_IF(static_cast<size_t>(key) >= obs_size || key < 0, |
| 189 | + "Invalid observable key"); |
| 190 | + |
| 191 | + auto &&[obs, type] = observables_[key]; |
| 192 | + obs_vec.push_back(obs); |
| 193 | + } |
| 194 | + |
| 195 | + observables_.push_back(std::make_pair( |
| 196 | + std::make_shared<Pennylane::LightningQubit::Observables:: |
| 197 | + Hamiltonian<VectorStateT>>( |
| 198 | + Pennylane::LightningQubit::Observables::Hamiltonian< |
| 199 | + VectorStateT>(coeffs, std::move(obs_vec))), |
| 200 | + ObsType::Hamiltonian)); |
| 201 | + |
| 202 | + return static_cast<ObsIdType>(obs_size); |
| 203 | + } |
| 204 | +}; |
| 205 | +} // namespace Catalyst::Runtime::Simulator |
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