Normal Ordering of states #
For a field specification π
, π.normalOrderRel
is a relation on π.CrAnFieldOp
representing normal ordering. It is defined such that π.normalOrderRel Οβ Οβ
is true if one of the following is true
Οβ
is a field creation operatorΟβ
is a field annihilation operator.
Thus, colloquially π.normalOrderRel Οβ Οβ
says the creation operators are less than
annihilation operators.
Equations
- FieldSpecification.normalOrderRel a b = (π.crAnFieldOpToCreateAnnihilate a).normalOrder (π.crAnFieldOpToCreateAnnihilate b)
Instances For
Normal ordering is total.
Normal ordering is transitive.
A decidable instance on the normal ordering relation.
Equations
Normal order sign. #
For a field specification π
, and a list Οs
of π.CrAnFieldOp
, π.normalOrderSign Οs
is the
sign corresponding to the number of fermionic
-fermionic
exchanges undertaken to normal-order
Οs
using the insertion sort algorithm.
Equations
Instances For
##Β Normal order of lists
For a field specification π
, and a list Οs
of π.CrAnFieldOp
,
π.normalOrderList Οs
is the list Οs
normal-ordered using the
insertion sort algorithm. It puts creation operators on the left and annihilation operators on
the right. For example:
π.normalOrderList [Ο1c, Ο1a, Ο2c, Ο2a] = [Ο1c, Ο2c, Ο1a, Ο2a]
Equations
Instances For
For a list of creation and annihilation states, the equivalence between
Fin Οs.length
and Fin (normalOrderList Οs).length
taking each position in Οs
to it's corresponding position in the normal ordered list. This assumes that
we are using the insertion sort method.
For example:
- For
[Ο1c, Ο1a, Ο2c, Ο2a]
this equivalence sends0 β¦ 0
,1 β¦ 2
,2 β¦ 1
,3 β¦ 3
.
Equations
Instances For
For a field specification π
, a list Οs = Οββ¦Οβ
of π.CrAnFieldOp
and an i < Οs.length
,
then
normalOrderSign (Οββ¦Οα΅’ββΟα΅’βββ¦Οβ)
is equal to the product of
normalOrderSign Οββ¦Οβ
,π’(Οα΅’, Οββ¦Οα΅’ββ)
i.e. the sign needed to removeΟα΅’
fromΟββ¦Οβ
,π’(Οα΅’, _)
where_
is the list of elements appearing beforeΟα΅’
after normal ordering, i.e. the sign needed to insertΟα΅’
back into the normal-ordered list at the correct place.