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
Οβis a field creation operatorΟβis 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.