(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

I need to find the expectation value for E but I don't know how b acts on the vacuum state.

2. Relevant equations

[tex]

b = \int dt \phi^{*}(t) \hat{{\cal E}}_{in}(t)

[/tex]

[tex]

| \psi(t)\rangle = b^\dagger| 0\rangle

[/tex]

3. The attempt at a solution

[tex]

\langle \psi(t) | \hat{{\cal E}}^\dagger\hat{{\cal E}}| \psi(t)\rangle =

[/tex]

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Homework Help: Quantum Mechanics: Expectation values

**Physics Forums | Science Articles, Homework Help, Discussion**