test_density.py 文件源码

def test_eval_trace():
    up = JzKet(S(1)/2, S(1)/2)
    down = JzKet(S(1)/2, -S(1)/2)
    d = Density((up, 0.5), (down, 0.5))

    t = Tr(d)
    assert t.doit() == 1

    #test dummy time dependent states
    class TestTimeDepKet(TimeDepKet):
        def _eval_trace(self, bra, **options):
            return 1

    x, t = symbols('x t')
    k1 = TestTimeDepKet(0, 0.5)
    k2 = TestTimeDepKet(0, 1)
    d = Density([k1, 0.5], [k2, 0.5])
    assert d.doit() == (0.5 * OuterProduct(k1, k1.dual) +
                        0.5 * OuterProduct(k2, k2.dual))

    t = Tr(d)
    assert t.doit() == 1