Student Friendly Introduction to QFT · Problem 7.6

QED: Quantum Field Interaction Theory Applied to Electromagnetism

Physics — QFT · vacuum-expectation-value-photon

Problem

Show that the vacuum expectation value (VEV) for the photon field is zero, i.e.,

\langle 0 | A^\mu | 0 \rangle = 0

. Pick any state you like and show that the expectation value of

A^\mu

for that state is zero.