# qml.FermiC¶

class FermiC(orbital)[source]

Bases: pennylane.fermi.fermionic.FermiWord

The fermionic creation operator $$a^{\dagger}$$

For instance, the operator qml.FermiC(2) denotes $$a^{\dagger}_2$$. This operator applied to $$\ket{0000}$$ gives $$\ket{0010}$$.

Parameters

orbital (int) – the non-negative integer indicating the orbital the operator acts on.

Note

While the FermiC class represents a mathematical operator, it is not a PennyLane qubit Operator.

Example

To construct the operator $$a^{\dagger}_0$$:

>>> FermiC(0)
a⁺(0)


This can be combined with the annihilation operator FermiA. For example, $$a^{\dagger}_0 a_1 a^{\dagger}_2 a_3$$ can be constructed as:

>>> qml.FermiC(0) * qml.FermiA(1) * qml.FermiC(2) * qml.FermiA(3)
a⁺(0) a(1) a⁺(2) a(3)

 wires Return wires in a FermiWord.
wires

Return wires in a FermiWord.

 fromkeys([value]) Create a new dictionary with keys from iterable and values set to value. get(key[, default]) Return the value for key if key is in the dictionary, else default. pop(k[,d]) If key is not found, default is returned if given, otherwise KeyError is raised Remove and return a (key, value) pair as a 2-tuple. setdefault(key[, default]) Insert key with a value of default if key is not in the dictionary. Return a compact string representation of a FermiWord. update(item) Restrict updating FermiWord after instantiation.
clear()None.  Remove all items from D.
copy()a shallow copy of D
fromkeys(value=None, /)

Create a new dictionary with keys from iterable and values set to value.

get(key, default=None, /)

Return the value for key if key is in the dictionary, else default.

items()a set-like object providing a view on D’s items
keys()a set-like object providing a view on D’s keys
pop(k[, d])v, remove specified key and return the corresponding value.

If key is not found, default is returned if given, otherwise KeyError is raised

popitem()

Remove and return a (key, value) pair as a 2-tuple.

Pairs are returned in LIFO (last-in, first-out) order. Raises KeyError if the dict is empty.

setdefault(key, default=None, /)

Insert key with a value of default if key is not in the dictionary.

Return the value for key if key is in the dictionary, else default.

to_string()

Return a compact string representation of a FermiWord. Each operator in the word is represented by the number of the wire it operates on, and a + or - to indicate either a creation or annihilation operator.

>>> w = FermiWord({(0, 0) : '+', (1, 1) : '-'})
>>> w.to_string()
a⁺(0) a(1)

update(item)

Restrict updating FermiWord after instantiation.

values()an object providing a view on D’s values