!2273 manybody models

Merge pull request !2273 from 杨金元/manybody

mindquantum/algorithm/manybody/bak.manybody_model.py

@@ -0,0 +1,126 @@
+# Copyright 2023 Huawei Technologies Co., Ltd
+#
+# 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.
+# ============================================================================
+"""Base many-body model."""
+from abc import ABC, abstractmethod
+from numbers import Number
+from typing import List, Union
+
+import numpy as np
+
+from mindquantum.core.operators import QubitOperator, ground_state_of_sum_zz
+from mindquantum.device import QubitsTopology
+from mindquantum.utils.f import random_rng
+
+
+class ManyBodyModel(ABC):
+    def __init__(self, lattice: QubitsTopology):
+        self.lattice = lattice
+
+    @abstractmethod
+    def get_hamiltonian(self):
+        raise NotImplementedError
+
+    def get_site_num(self):
+        return self.lattice.size()
+
+    @abstractmethod
+    def random_configuration(self, seed: int = None):
+        raise NotImplementedError
+
+    def ground_state_energy(self, *args, **kwargs):
+        raise RuntimeWarning("Method of calculating ground state of this model is not found.")
+
+
+class IsingModel(ManyBodyModel):
+    """
+    H = sum_ij J_ij sigma_i sigma_j + sum_i h_i sigma_i
+    """
+
+    def __init__(self, lattice: QubitsTopology, J: Union[float, List[float]] = -1, h: Union[float, List[float]] = 0):
+        super().__init__(lattice)
+        self.J, self.h = 0, 0
+        self.set_coupling_strength(J)
+        self.set_external_field_strength(h)
+
+    def set_coupling_strength(self, J: Union[float, List[float]]):
+        if not isinstance(J, Number):
+            try:
+                if len(J) != self.lattice.n_edges():
+                    raise ValueError(
+                        f"The size of J should be the number of coupling edge of lattice ({self.lattice.n_edges()})"
+                    )
+                self.J = J
+            except TypeError:
+                raise TypeError(f"J should be a number or a iterable of number, but get {type(J)}.")
+        else:
+            self.J = np.ones(self.lattice.n_edges()) * J
+
+    def set_external_field_strength(self, h: Union[float, List[float]]):
+        if not isinstance(h, Number):
+            try:
+                if len(h) != self.lattice.size():
+                    raise ValueError(
+                        f"The size of h should be the number of size of lattice ({self.lattice.size()}), but get {len(h)}"
+                    )
+                self.h = h
+            except TypeError:
+                raise TypeError(f"h should be a number or a iterable of number, but get {type(h)}.")
+        else:
+            self.h = np.ones(self.lattice.size()) * h
+
+    def get_hamiltonian(self):
+        sorted_edges = sorted(list(self.lattice.edges_with_id()))
+        sorted_site = sorted(list(self.lattice.all_qubit_id()))
+        ham = QubitOperator()
+        for (i, j), J in zip(sorted_edges, self.J):
+            ham += QubitOperator(f"Z{i} Z{j}", J)
+        for i, h in zip(sorted_site, self.h):
+            ham += QubitOperator(f"Z{i}", h)
+        return ham
+
+    def random_configuration(self, seed: int = None):
+        rng = random_rng(seed)
+        J = rng.random(self.lattice.n_edges()) * 2 - 1
+        h = rng.random(self.lattice.size()) * 2 - 1
+        self.set_coupling_strength(J)
+        self.set_external_field_strength(h)
+
+    def ground_state_energy(self, sim: str = 'mqvector', *args, **kwargs):
+        return ground_state_of_sum_zz(self.get_hamiltonian(), sim)
+
+
+class XYZModel(ManyBodyModel):
+    pass
+
+
+class XXZModel(ManyBodyModel):
+    pass
+
+
+class FermionHubbardModel(ManyBodyModel):
+    pass
+
+
+class BoseHubbardModel(ManyBodyModel):
+    pass
+
+
+if __name__ == '__main__':
+    from mindquantum.device.lattice import GridQubits
+
+    lattice = GridQubits(3, 3)
+    ising_model = IsingModel(lattice)
+    ham = ising_model.get_hamiltonian()
+    ising_model.random_configuration()