chore: 添加虚拟环境到仓库

- 添加 backend_service/venv 虚拟环境
- 包含所有Python依赖包
- 注意：虚拟环境约393MB，包含12655个文件

backend_service/venv/lib/python3.13/site-packages/sympy/physics/paulialgebra.py

@@ -0,0 +1,231 @@
+"""
+This module implements Pauli algebra by subclassing Symbol. Only algebraic
+properties of Pauli matrices are used (we do not use the Matrix class).
+
+See the documentation to the class Pauli for examples.
+
+References
+==========
+
+.. [1] https://en.wikipedia.org/wiki/Pauli_matrices
+"""
+
+from sympy.core.add import Add
+from sympy.core.mul import Mul
+from sympy.core.numbers import I
+from sympy.core.power import Pow
+from sympy.core.symbol import Symbol
+from sympy.physics.quantum import TensorProduct
+
+__all__ = ['evaluate_pauli_product']
+
+
+def delta(i, j):
+    """
+    Returns 1 if ``i == j``, else 0.
+
+    This is used in the multiplication of Pauli matrices.
+
+    Examples
+    ========
+
+    >>> from sympy.physics.paulialgebra import delta
+    >>> delta(1, 1)
+    1
+    >>> delta(2, 3)
+    0
+    """
+    if i == j:
+        return 1
+    else:
+        return 0
+
+
+def epsilon(i, j, k):
+    """
+    Return 1 if i,j,k is equal to (1,2,3), (2,3,1), or (3,1,2);
+    -1 if ``i``,``j``,``k`` is equal to (1,3,2), (3,2,1), or (2,1,3);
+    else return 0.
+
+    This is used in the multiplication of Pauli matrices.
+
+    Examples
+    ========
+
+    >>> from sympy.physics.paulialgebra import epsilon
+    >>> epsilon(1, 2, 3)
+    1
+    >>> epsilon(1, 3, 2)
+    -1
+    """
+    if (i, j, k) in ((1, 2, 3), (2, 3, 1), (3, 1, 2)):
+        return 1
+    elif (i, j, k) in ((1, 3, 2), (3, 2, 1), (2, 1, 3)):
+        return -1
+    else:
+        return 0
+
+
+class Pauli(Symbol):
+    """
+    The class representing algebraic properties of Pauli matrices.
+
+    Explanation
+    ===========
+
+    The symbol used to display the Pauli matrices can be changed with an
+    optional parameter ``label="sigma"``. Pauli matrices with different
+    ``label`` attributes cannot multiply together.
+
+    If the left multiplication of symbol or number with Pauli matrix is needed,
+    please use parentheses  to separate Pauli and symbolic multiplication
+    (for example: 2*I*(Pauli(3)*Pauli(2))).
+
+    Another variant is to use evaluate_pauli_product function to evaluate
+    the product of Pauli matrices and other symbols (with commutative
+    multiply rules).
+
+    See Also
+    ========
+
+    evaluate_pauli_product
+
+    Examples
+    ========
+
+    >>> from sympy.physics.paulialgebra import Pauli
+    >>> Pauli(1)
+    sigma1
+    >>> Pauli(1)*Pauli(2)
+    I*sigma3
+    >>> Pauli(1)*Pauli(1)
+    1
+    >>> Pauli(3)**4
+    1
+    >>> Pauli(1)*Pauli(2)*Pauli(3)
+    I
+
+    >>> from sympy.physics.paulialgebra import Pauli
+    >>> Pauli(1, label="tau")
+    tau1
+    >>> Pauli(1)*Pauli(2, label="tau")
+    sigma1*tau2
+    >>> Pauli(1, label="tau")*Pauli(2, label="tau")
+    I*tau3
+
+    >>> from sympy import I
+    >>> I*(Pauli(2)*Pauli(3))
+    -sigma1
+
+    >>> from sympy.physics.paulialgebra import evaluate_pauli_product
+    >>> f = I*Pauli(2)*Pauli(3)
+    >>> f
+    I*sigma2*sigma3
+    >>> evaluate_pauli_product(f)
+    -sigma1
+    """
+
+    __slots__ = ("i", "label")
+
+    def __new__(cls, i, label="sigma"):
+        if i not in [1, 2, 3]:
+            raise IndexError("Invalid Pauli index")
+        obj = Symbol.__new__(cls, "%s%d" %(label,i), commutative=False, hermitian=True)
+        obj.i = i
+        obj.label = label
+        return obj
+
+    def __getnewargs_ex__(self):
+        return (self.i, self.label), {}
+
+    def _hashable_content(self):
+        return (self.i, self.label)
+
+    # FIXME don't work for -I*Pauli(2)*Pauli(3)
+    def __mul__(self, other):
+        if isinstance(other, Pauli):
+            j = self.i
+            k = other.i
+            jlab = self.label
+            klab = other.label
+
+            if jlab == klab:
+                return delta(j, k) \
+                    + I*epsilon(j, k, 1)*Pauli(1,jlab) \
+                    + I*epsilon(j, k, 2)*Pauli(2,jlab) \
+                    + I*epsilon(j, k, 3)*Pauli(3,jlab)
+        return super().__mul__(other)
+
+    def _eval_power(b, e):
+        if e.is_Integer and e.is_positive:
+            return super().__pow__(int(e) % 2)
+
+
+def evaluate_pauli_product(arg):
+    '''Help function to evaluate Pauli matrices product
+    with symbolic objects.
+
+    Parameters
+    ==========
+
+    arg: symbolic expression that contains Paulimatrices
+
+    Examples
+    ========
+
+    >>> from sympy.physics.paulialgebra import Pauli, evaluate_pauli_product
+    >>> from sympy import I
+    >>> evaluate_pauli_product(I*Pauli(1)*Pauli(2))
+    -sigma3
+
+    >>> from sympy.abc import x
+    >>> evaluate_pauli_product(x**2*Pauli(2)*Pauli(1))
+    -I*x**2*sigma3
+    '''
+    start = arg
+    end = arg
+
+    if isinstance(arg, Pow) and isinstance(arg.args[0], Pauli):
+        if arg.args[1].is_odd:
+            return arg.args[0]
+        else:
+            return 1
+
+    if isinstance(arg, Add):
+        return Add(*[evaluate_pauli_product(part) for part in arg.args])
+
+    if isinstance(arg, TensorProduct):
+        return TensorProduct(*[evaluate_pauli_product(part) for part in arg.args])
+
+    elif not(isinstance(arg, Mul)):
+        return arg
+
+    while not start == end or start == arg and end == arg:
+        start = end
+
+        tmp = start.as_coeff_mul()
+        sigma_product = 1
+        com_product = 1
+        keeper = 1
+
+        for el in tmp[1]:
+            if isinstance(el, Pauli):
+                sigma_product *= el
+            elif not el.is_commutative:
+                if isinstance(el, Pow) and isinstance(el.args[0], Pauli):
+                    if el.args[1].is_odd:
+                        sigma_product *= el.args[0]
+                elif isinstance(el, TensorProduct):
+                    keeper = keeper*sigma_product*\
+                        TensorProduct(
+                            *[evaluate_pauli_product(part) for part in el.args]
+                        )
+                    sigma_product = 1
+                else:
+                    keeper = keeper*sigma_product*el
+                    sigma_product = 1
+            else:
+                com_product *= el
+        end = tmp[0]*keeper*sigma_product*com_product
+        if end == arg: break
+    return end