SupportsApplyUnitary

class SupportsApplyUnitary(*args, **kwargs)

Bases: Protocol

A mirror of the ffsim.SupportsApplyUnitary protocol.

See apply_unitary() for the type-agnostic helper function dispatching to the method below.

>>> import numpy as np
>>> from qiskit_fermions.circuit.library import OrbitalRotation
>>> gate = OrbitalRotation(np.eye(2))
>>> vec = np.array([1.0, 0.0], dtype=complex)
>>> gate._apply_unitary_(vec, norb=2, nelec=1, copy=True)
array([1.+0.j, 0.+0.j])

Protocol Methods

_apply_unitary_(vec, norb, nelec, copy)

Applies a unitary transformation to a state vector.

Parameters:

  • vec (np.ndarray) – the state vector to apply the unitary transformation to.

  • norb (int) – the number of spatial orbitals.

  • nelec (int | tuple[int, int]) – either a single integer representing the number of fermions for a spinless system, or a pair of integers storing the numbers of spin alpha and spin beta fermions.

  • copy (bool) –

    whether to copy the vector before operating on it.

    • If copy=True then this method always returns a newly allocated vector and the original vector is left untouched.

    • If copy=False then this method may still return a newly allocated vector, but the original vector may have its data overwritten. It is also possible that the original vector is returned, modified in-place.

Returns:

The transformed vector.

Return type:

np.ndarray