Equivalence of the Klein-Gordon random field and the complex Klein-Gordon quantum field

Abstract

The difference between a Klein-Gordon random field and the complex Klein-Gordon quantum field is characterized, explicitly comparing the roles played by negative-frequency modes of test functions in creation and annihilation operator presentations of the two theories. The random field and the complex quantum field can both be constructed from the same creation and annihilation operator algebra, making them equivalent in that sense. © 2009 Europhysics Letters Association.