Quantisation of Fields
Pierre VAN BAAL · 2016
As position is no longer a quantum observable but free particles do not seem to be in contradiction with relativistic invariance, we can try to introduce such a free particle as a quantum observable. This observable is hence described by a plane wave ( 2.1 ) φ k → ( x → , t ) = e − i ( k → o t − x → ⋅ k → ) / ℏ , https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429073601/5d786806-46dc-40d1-b4d3-a3e5f58ba76e/content/equ_31.tif"/>