qml.bose.BoseWord

class BoseWord(operator)

Bases: dict

Dictionary used to represent a Bose word, a product of bosonic creation and annihilation operators, that can be constructed from a standard dictionary.

The keys of the dictionary are tuples of two integers. The first integer represents the position of the creation/annihilation operator in the Bose word and the second integer represents the mode it acts on. The values of the dictionary are one of '+' or '-' symbols that denote creation and annihilation operators, respectively. The operator \(b^{\dagger}_0 b_1\) can then be constructed as

>>> w = qml.BoseWord({(0, 0) : '+', (1, 1) : '-'})
>>> print(w)
b⁺(0) b(1)

Attributes

wires

Return wires in a BoseWord.

wires

Return wires in a BoseWord.

Methods

adjoint()	Return the adjoint of BoseWord.
clear()
copy()
fromkeys([value])	Create a new dictionary with keys from iterable and values set to value.
get(key[, default])	Return the value for key if key is in the dictionary, else default.
items()	Returns the dictionary items in sorted order.
keys()
normal_order()	Convert a BoseWord to its normal-ordered form.
pop(k[,d])	If the key is not found, return the default if given; otherwise, raise a KeyError.
popitem()	Remove and return a (key, value) pair as a 2-tuple.
setdefault(key[, default])	Insert key with a value of default if key is not in the dictionary.
shift_operator(initial_position, final_position)	Shifts an operator in the BoseWord from initial_position to final_position by applying the bosonic commutation relations.
to_string()	Return a compact string representation of a BoseWord.
update(item)	Restrict updating BoseWord after instantiation.
values()

adjoint()

Return the adjoint of BoseWord.

clear() → None.  Remove all items from D.

copy() → a shallow copy of D

fromkeys(value=None, /)

Create a new dictionary with keys from iterable and values set to value.

get(key, default=None, /)

Return the value for key if key is in the dictionary, else default.

items()

Returns the dictionary items in sorted order.

keys() → a set-like object providing a view on D's keys

normal_order()

Convert a BoseWord to its normal-ordered form.

>>> bw = qml.BoseWord({(0, 0): "-", (1, 0): "-", (2, 0): "+", (3, 0): "+"})
>>> print(bw.normal_order())
4.0 * b⁺(0) b(0)
+ 2.0 * I
+ 1.0 * b⁺(0) b⁺(0) b(0) b(0)

pop(k[, d]) → v, remove specified key and return the corresponding value.

If the key is not found, return the default if given; otherwise, raise a KeyError.

popitem()

Remove and return a (key, value) pair as a 2-tuple.

Pairs are returned in LIFO (last-in, first-out) order. Raises KeyError if the dict is empty.

setdefault(key, default=None, /)

Insert key with a value of default if key is not in the dictionary.

Return the value for key if key is in the dictionary, else default.

shift_operator(initial_position, final_position)

Shifts an operator in the BoseWord from initial_position to final_position by applying the bosonic commutation relations.

Parameters

• initial_position (int) – the position of the operator to be shifted

• final_position (int) – the desired position of the operator

Returns

The BoseSentence obtained after applying the commutator relations.

Return type

BoseSentence

Raises

• TypeError – if initial_position or final_position is not an integer

• ValueError – if initial_position or final_position are outside the range [0, len(BoseWord) - 1] where len(BoseWord) is the number of operators in the BoseWord.

to_string()

Return a compact string representation of a BoseWord. Each operator in the word is represented by the number of the wire it operates on, and a + or - to indicate either a creation or annihilation operator.

>>> w = qml.BoseWord({(0, 0) : '+', (1, 1) : '-'})
>>> w.to_string()
'b⁺(0) b(1)'

update(item)

Restrict updating BoseWord after instantiation.

values() → an object providing a view on D's values

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