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from pytest import raises |
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import sympy |
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from sympy.physics.quantum import Dagger, AntiCommutator, qapply |
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from sympy.physics.quantum.fermion import FermionOp |
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from sympy.physics.quantum.fermion import FermionFockKet, FermionFockBra |
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from sympy import Symbol |
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def test_fermionoperator(): |
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c = FermionOp('c') |
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d = FermionOp('d') |
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assert isinstance(c, FermionOp) |
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assert isinstance(Dagger(c), FermionOp) |
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assert c.is_annihilation |
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assert not Dagger(c).is_annihilation |
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assert FermionOp("c") == FermionOp("c", True) |
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assert FermionOp("c") != FermionOp("d") |
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assert FermionOp("c", True) != FermionOp("c", False) |
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assert AntiCommutator(c, Dagger(c)).doit() == 1 |
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assert AntiCommutator(c, Dagger(d)).doit() == c * Dagger(d) + Dagger(d) * c |
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def test_fermion_states(): |
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c = FermionOp("c") |
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assert (FermionFockBra(0) * FermionFockKet(1)).doit() == 0 |
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assert (FermionFockBra(1) * FermionFockKet(1)).doit() == 1 |
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assert qapply(c * FermionFockKet(1)) == FermionFockKet(0) |
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assert qapply(c * FermionFockKet(0)) == 0 |
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assert qapply(Dagger(c) * FermionFockKet(0)) == FermionFockKet(1) |
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assert qapply(Dagger(c) * FermionFockKet(1)) == 0 |
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def test_power(): |
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c = FermionOp("c") |
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assert c**0 == 1 |
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assert c**1 == c |
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assert c**2 == 0 |
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assert c**3 == 0 |
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assert Dagger(c)**1 == Dagger(c) |
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assert Dagger(c)**2 == 0 |
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assert (c**Symbol('a')).func == sympy.core.power.Pow |
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assert (c**Symbol('a')).args == (c, Symbol('a')) |
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with raises(ValueError): |
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c**-1 |
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with raises(ValueError): |
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c**3.2 |
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with raises(TypeError): |
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c**1j |
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