Merge pull request #25 from yangguohao/task77

[PaddlePaddle Hackathon]77 为哈密顿量矩阵实现指定量子比特数

Author: QuLeaf

paddle_quantum/circuit.py

@@ -59,7 +59,7 @@ def __init__(self, n):
                         paddle.to_tensor(np.array([math.pi / 4])), paddle.to_tensor(np.array([-math.pi / 4]))]
         # Record history of adding gates to the circuit
         self.__history = []
-        
+
     def expand(self,new_n):
         """
         为原来的量子电路进行比特数扩展
@@ -82,7 +82,7 @@ def expand(self,new_n):
             _state = kron(self.__state,_state)
             self.__state = _state
         self.n = new_n
-        
+
     def __add__(self, cir):
         r"""重载加法 ‘+’ 运算符，用于拼接两个维度相同的电路
 

paddle_quantum/utils.py

@@ -914,17 +914,21 @@ def decompose_pauli_words(self):
             pass
         return self.coefficients, self.__pauli_words
 
-    def construct_h_matrix(self):
+    def construct_h_matrix(self, n_qubit=None):
         r"""构建 Hamiltonian 在 Z 基底下的矩阵。
 
         Returns:
             np.ndarray: Z 基底下的哈密顿量矩阵形式
         """
         coefs, pauli_words, sites = self.decompose_with_sites()
-        n_qubit = 1
-        for site in sites:
-            if type(site[0]) is int:
-                n_qubit = max(n_qubit, max(site) + 1)
+        if n_qubit is None:
+            n_qubit = 1
+            for site in sites:
+                if type(site[0]) is int:
+                    print(n_qubit,(site))
+                    n_qubit = max(n_qubit, max(site) + 1)
+        else:
+            assert n_qubit>=self.n_qubits,"输入的量子数不小于哈密顿量表达式中所对应的量子比特数"
         h_matrix = np.zeros([2 ** n_qubit, 2 ** n_qubit], dtype='complex64')
         spin_ops = SpinOps(n_qubit, use_sparse=True)
         for idx in range(len(coefs)):

test_documents/test_construct_h_matrix.py

@@ -0,0 +1,6 @@
+from paddle_quantum.utils import Hamiltonian
+
+h = Hamiltonian([(1, 'Z0, Z1')])
+
+print(h.construct_h_matrix())
+print(h.construct_h_matrix(4))