ffsim.GivensAnsatzOp

class ffsim.GivensAnsatzOp(norb, interaction_pairs, thetas, phis, phase_angles)

Bases: SupportsApplyUnitary, SupportsApproximateEquality

A Givens rotation ansatz operator.

The Givens rotation ansatz consists of a sequence of Givens rotations followed by a layer of single-orbital phase gates.

Note that this ansatz does not implement any interactions between spin alpha and spin beta orbitals.

Attributes

norb	The number of spatial orbitals.
interaction_pairs	The orbital pairs to apply the Givens rotations to.
thetas	The angles for the Givens rotations.
phis	The optional phase angles for the Givens rotations.
phase_angles	The optional phase angles for the layer of single-orbital phase gates.

norb: int

The number of spatial orbitals.

interaction_pairs: list[tuple[int, int]]

The orbital pairs to apply the Givens rotations to.

thetas: ndarray

The angles for the Givens rotations.

phis: ndarray | None

The optional phase angles for the Givens rotations.

phase_angles: ndarray | None

The optional phase angles for the layer of single-orbital phase gates.

Methods

from_orbital_rotation(orbital_rotation)	Initialize the operator from an orbital rotation.
from_parameters(params, norb, interaction_pairs)	Initialize the operator from a real-valued parameter vector.
n_params(norb, interaction_pairs[, ...])	Return the number of parameters of an ansatz with given settings.
to_orbital_rotation()	Convert the Givens ansatz operator to an orbital rotation.
to_parameters()	Convert the operator to a real-valued parameter vector.

static from_orbital_rotation(orbital_rotation)

Initialize the operator from an orbital rotation.

Parameters:

orbital_rotation (ndarray) – The orbital rotation.

Return type:

GivensAnsatzOp

static from_parameters(params, norb, interaction_pairs, with_phis=True, with_phase_angles=True)

Initialize the operator from a real-valued parameter vector.

Parameters:

• params (ndarray) – The real-valued parameter vector.

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

• interaction_pairs (list[tuple[int, int]]) – The orbital pairs to apply the Givens rotation gates to.

• with_phis (bool) – Whether to include complex phases for the Givens rotations.

• with_phase_angles (bool) – Whether to include a layer of single-orbital phase gates.

Return type:

GivensAnsatzOp

static n_params(norb, interaction_pairs, with_phis=True, with_phase_angles=True)

Return the number of parameters of an ansatz with given settings.

Parameters:

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

• interaction_pairs (list[tuple[int, int]]) – The orbital pairs to apply the Givens rotation gates to.

• with_phis (bool) – Whether to include complex phases for the Givens rotations.

• with_phase_angles (bool) – Whether to include a layer of single-orbital phase gates.

Return type:

int

to_orbital_rotation()

Convert the Givens ansatz operator to an orbital rotation.

Return type:

ndarray

to_parameters()

Convert the operator to a real-valued parameter vector.

Return type:

ndarray