Let phi(x) and phi_dagger(x) be field operators which satisfy the appropriate commutation relations.(adsbygoogle = window.adsbygoogle || []).push({});

Then is there any analytic approximation for the two particle density matrix given by

<phi_dagger(x)phi_dagger(x')phi(x')phi(x)>

Thanks!

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

Dismiss Notice

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!

# Is there any approximation to the two particle density matrix

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