fulqrum.core.FermionicOperator¶

class FermionicOperator¶

Operator class for Fermionic operators

Parameters:

width (int) – Number of modes
operators (list) – List of tuples for terms in Hamiltonian

Example:

import fulqrum as fq
fq.FermionicOperator(5, [("++--", [0, 0, 1, 4], -0.018), ("+-", [3, 2], 0.4)])

<FermionicOperator[('+:0 +:0 -:1 -:4', (-0.018+0j)), ('-:2 +:3', (-0.4+0j))], width=5>

Methods

`append`(self, FermionicOperator other)
`coefficients`(self)	Return the coefficients for each term in the operator
`deflate_repeated_indices`(self)	Collapse repeated indices into singles and remove zero terms
`extended_jw_transformation`(self)	Jordan-Wigner transformation over extended alphabet from Fermionic -> Qubit operator
`from_dict`(self, dict dic)	FermionicOperator from dictionary
`from_json`(self, filename)	Load operator from a JSON or XZ file.
`from_label`(self, size_t width, str label=, ...)	Create FermionicOperator from a string label
`to_dict`(self)	Dictionary representation of FermionicOperator
`to_json`(self, filename[, overwrite])	Save operator to a JSON or XZ file.
`weights`(self)	Weight of each term in the operator

Attributes

`coeff`	Return the coeff for a single term or empty operator
`num_terms`	Return the number of terms in the operator
`operators`	Return the operators for a single term or empty operator
`width`	Width of operator

append(self, FermionicOperator other) → void¶

coeff¶

Return the coeff for a single term or empty operator

Returns:: complex

coefficients(self)¶

Return the coefficients for each term in the operator

Returns:: complex-valued array of coefficients
Return type:: ndarray

deflate_repeated_indices(self)¶

Collapse repeated indices into singles and remove zero terms

Returns:: Deflated operator
Return type:: FermionicOperator

extended_jw_transformation(self)¶: Jordan-Wigner transformation over extended alphabet from Fermionic -> Qubit operator

classmethod from_dict(self, dict dic)¶

FermionicOperator from dictionary

Parameters:: dic (dict) – Dictionary representation of operator
Returns:: FermionicOperator

classmethod from_json(self, filename)¶

Load operator from a JSON or XZ file.

Parameters:: filename (str) – File to load from
Returns:: FermionicOperator

classmethod from_label(self, size_t width, str label='', double complex coeff=1.0)¶

Create FermionicOperator from a string label

Parameters:

width (int) – Width of operator
label (str) – Label of operator
coeff (complex) – Complex coefficient, default=1.0

Returns:

FermionicOperator

num_terms¶

Return the number of terms in the operator

Returns:: Number of terms in operator
Return type:: int

operators¶

Return the operators for a single term or empty operator

Returns:: List of operator index tuples, if any, else None
Return type:: list or None

Notes

This returns a list of tuples to allow for multiple indices in Fermionic operators

to_dict(self)¶

Dictionary representation of FermionicOperator

Returns:: Dictionary representation of FermionicOperator
Return type:: dict

to_json(self, filename, overwrite=False)¶

Save operator to a JSON or XZ file. File extension can be ‘json’ or ‘xz’, the latter or which does LZMA compression which is recommended for large operators.

Parameters:

filename (str) – File to store to
overwrite (bool) – Overwrite file if it exits, default=False

weights(self)¶

Weight of each term in the operator

Returns:: Array of operator weights
Return type:: ndarray

width¶

Width of operator

Returns:: int