Anticommutator¶

The anti-commutator: {A,B} = A*B + B*A.

class sympy.physics.quantum.anticommutator.AntiCommutator(A, B)[source]¶

The standard anticommutator, in an unevaluated state.

Parameters

A : Expr

The first argument of the anticommutator {A,B}.

B : Expr

The second argument of the anticommutator {A,B}.

Explanation

Evaluating an anticommutator is defined [R664] as: {A, B} = A*B + B*A. This class returns the anticommutator in an unevaluated form. To evaluate the anticommutator, use the .doit() method.

Canonical ordering of an anticommutator is {A, B} for A < B. The arguments of the anticommutator are put into canonical order using __cmp__. If B < A, then {A, B} is returned as {B, A}.

Examples

>>> from sympy import symbols
>>> from sympy.physics.quantum import AntiCommutator
>>> from sympy.physics.quantum import Operator, Dagger
>>> x, y = symbols('x,y')
>>> A = Operator('A')
>>> B = Operator('B')

Create an anticommutator and use doit() to multiply them out.

>>> ac = AntiCommutator(A,B); ac
{A,B}
>>> ac.doit()
A*B + B*A

The commutator orders it arguments in canonical order:

>>> ac = AntiCommutator(B,A); ac
{A,B}

Commutative constants are factored out:

>>> AntiCommutator(3*x*A,x*y*B)
3*x**2*y*{A,B}

Adjoint operations applied to the anticommutator are properly applied to the arguments:

>>> Dagger(AntiCommutator(A,B))
{Dagger(A),Dagger(B)}

References

R664(1,2): https://en.wikipedia.org/wiki/Commutator

doit(**hints)[source]¶: Evaluate anticommutator

Quantum Mechanics

Clebsch-Gordan Coefficients