Mapper

class zixy.fermion.mappings.Mapper[source]

Bases: ABC

Base class for fermion to qubit mappers.

abstractmethod encode(fermion_ops: Sequence[tuple[int, bool]]) → Contribution[float][source]

Encode a sequence of fermionic creation and annihilation operators to qubit operators.

Parameters:

fermion_ops – A sequence of tuples, where each tuple consists of an integer index indicating the mode and a boolean indicating whether it’s a creation (True) or annihilation (False) operator.

Returns:

The encoded contribution to a linear combination of qubit Pauli strings.

encode_ca(c: int, a: int) → Contribution[float][source]

Encode the product of a creation operator and an annihilation operator.

The operator is defined as

\[a^\dagger_c a_a.\]
Parameters:

  • c – The fermionic mode of the creation operator.

  • a – The fermionic mode of the annihilation operator.

Returns:

The encoded contribution.

encode_caca(c1: int, a1: int, c2: int, a2: int) → Contribution[float][source]

Encode the product of two creation-annihilation operator products.

The operator is defined as

\[a^\dagger_{c1} a_{a1} a^\dagger_{c2} a_{a2}.\]
Parameters:

  • c1 – The fermionic mode of the first creation operator.

  • a1 – The fermionic mode of the first annihilation operator.

  • c2 – The fermionic mode of the second creation operator.

  • a2 – The fermionic mode of the second annihilation operator.

Returns:

The encoded contribution.

encode_ccaa(c1: int, c2: int, a1: int, a2: int) → Contribution[float][source]

Encode the product of two creation operators and two annihilation operators.

The operator is defined as

\[a^\dagger_{c1} a^\dagger_{c2} a_{a1} a_{a2}.\]
Parameters:

  • c1 – The fermionic mode of the first creation operator.

  • c2 – The fermionic mode of the second creation operator.

  • a1 – The fermionic mode of the first annihilation operator.

  • a2 – The fermionic mode of the second annihilation operator.

Returns:

The encoded contribution.

encode_n(i: int) → Contribution[float][source]

Encode the local number operator for a given mode.

The operator is defined as

\[n_i = a^\dagger_i a_i.\]
Parameters:

i – The fermionic mode to encode.

Returns:

The encoded contribution.

encode_nn(i: int, j: int) → Contribution[float][source]

Encode the product of two local number operators.

The operator is defined as

\[n_i n_j = a^\dagger_i a_i a^\dagger_j a_j.\]
Parameters:

  • i – The fermionic mode of the first number operator.

  • j – The fermionic mode of the second number operator.

Returns:

The encoded contribution.