Model of general expectation value calculation

class varipeps.expectation.model.Expectation_Model

Bases: ABC

Abstract model of an general expectation value calculated for the complete unit cell.

Parameters:

is_spiral_peps (bool) – Flag if the expectation value is for a spiral iPEPS ansatz.

abstract __call__(peps_tensors: Sequence[Array], unitcell: PEPS_Unit_Cell, spiral_vectors: Array | Sequence[Array] | None = None, *, normalize_by_size: bool = True, only_unique: bool = True) → Array | List[Array]

Calculate the expectation value for PEPS unitcell depending on the gates set in the class.

Parameters:

• peps_tensors (sequence of jax.numpy.ndarray) – The sequence of unique PEPS tensors in the unitcell.

• unitcell (PEPS_Unit_Cell) – The PEPS unitcell.

• spiral_vectors (single or sequence of jax.numpy.ndarray, optional) – If the expectation value is for a spiral iPEPS ansatz, in this argument the wavevectors are expected.

  Default: None

Keyword Arguments:

• normalize_by_size (bool, optional) – Flag if the expectation value should be normalized by the number of tensors in the unitcell.

  Default: True

• only_unique (bool, optional) – Flag if the expectation value should be calculated just once for each unique PEPS tensor in the unitcell.

  Default: True

Returns:

The expectation values for all gates. Single tensor if only one gate is applied.

Return type:

jax.numpy.ndarray or list of jax.numpy.ndarray