qcheff.operators.utils

Module Contents

Functions

eye_like	Identity operator in sparse format with the same shape as A.
commutator	Commutator of two operators.
tensor2	Tensor product of two operators.
tensor	Tensor product of multiple operators.
embed_operator	Identity wrapping for the appropriate operator.
state_number_enumerate	An iterator that enumerates all the state number tuples (quantum numbers of the form (n1, n2, n3, …)) for a system with dimensions given by dims.
state_number_index	Return the index of a quantum state corresponding to state, given a system with dimensions given by dims.
state_index_number	Return a quantum number representation given a state index, for a system of composite structure defined by dims.

API

eye_like(A)

Identity operator in sparse format with the same shape as A.

Parameters

A : array_like Operator

Returns

identity_operator : array_like Identity operator in sparse format with the same shape as A

commutator(A, B, kind='normal')

Commutator of two operators.

Parameters

A : array_like First operator B : array_like Second operator kind : str, optional Kind of commutator. Can be ‘normal’ or ‘anti’ (default is ‘normal’)

Returns

commutator : array_like Commutator of two operators

tensor2(A, B)

Tensor product of two operators.

Parameters

A : array_like First operator B : array_like Second operator

Returns

tensor_product : array_like Tensor product of two operators

tensor(*args)

Tensor product of multiple operators.

Parameters

*args : array_like Operators

Returns

tensor_product : array_like Tensor product of multiple operators

embed_operator(op, pos: int, system_dims: tuple[int, ...])

Identity wrapping for the appropriate operator.

Parameters

op : ndarray The operator to be wrapped. Ideally, it should have dimensions=ntrunc pos : int The position of the operator system_dims : tuple[int, …] The dimensions of the system

Returns

wrapped_operator : array_like The wrapped operator

state_number_enumerate(dims, excitations=None)

An iterator that enumerates all the state number tuples (quantum numbers of the form (n1, n2, n3, …)) for a system with dimensions given by dims.

Example:

>>> for state in state_number_enumerate([2,2]): # doctest: +SKIP
>>>     print(state) # doctest: +SKIP
( 0  0 )
( 0  1 )
( 1  0 )
( 1  1 )

Parameters

dims : list or array The quantum state dimensions array, as it would appear in a QuTiP Qobj.

excitations : integer, optional Restrict state space to states with excitation numbers below or equal to this value.

Returns

state_number : tuple Successive state number tuples that can be used in loops and other iterations, using standard state enumeration by definition.

state_number_index(dims, state)

Return the index of a quantum state corresponding to state, given a system with dimensions given by dims.

Example:

>>> state_number_index([2, 2, 2], [1, 1, 0])
6

Parameters

dims : list or array The quantum state dimensions array, as it would appear in a QuTiP Qobj.

state : list State number array.

Returns

idx : int The index of the state given by state in standard enumeration ordering.

state_index_number(dims, index)

Return a quantum number representation given a state index, for a system of composite structure defined by dims.

Example:

>>> state_index_number([2, 2, 2], 6)
[1, 1, 0]

Parameters

dims : list or array The quantum state dimensions array, as it would appear in a Qobj.

index : integer The index of the state in standard enumeration ordering.

Returns

state : tuple The state number tuple corresponding to index index in standard enumeration ordering.