Recent content by kvl

Thanks for the links !

On the first reading I've solved approx. one exercise from each chapter, but now I'm solving the remaining ones. And of course I've repeated some of the calculations in the text myself. What I want is some way to check myself. For example by solving exercises and checking if the answers were...

I'm trying to study QFT using P&S book. Now I'm on the chapter 13 but I feel that I'm rather bad at solving practical problems on QFT and QED. Could anyone suggest a good source of problems (preferably with solutions) on QFT and QED (near the level of P&S ch. 1-13) to practise ? Thanks in advance !

Yes, I understand the Wick's theorem and why we should divide. But what I don't understand is how can it be compatible with interpretation of diagrams in terms of virtual particles creation/anihilation !

I'm trying to understand Feynman diagrams interpretation in terms of virtual particles. What I still can't understand is how this interpretation is compatible with the fact that one should divide each diagram by its symmetry order. As far as I understand, diagram symmetry order means how many...

Hm, actually its quite more easy. Just consider the state proportional to |\psi\rangle = 3 a^\dag(k_1) |0\rangle + 7 a^\dag(k_1)a^\dag(k_1) |0\rangle. How many particles are in this state ? You can answer this question by calculating the mean number of particles: \frac{\langle\psi| N...

Take a look at http://en.wikipedia.org/wiki/Quantum_teleportation

Thanks, its very interesting reading ! Thanks, for the links.

AFAIK the trace of an operator is given by \mbox{tr}(\hat{f}) = \int dq \langle q | \hat{f} | q \rangle and can be undefined in infinite-dimension Hilbet space. But \langle q_0 | [p,q] | q_0 \rangle is just a scalar product of two vectors which should have finite value even in...

In standard quantization procedure we should apply commutation rules [p,q]=i. But let's do a simple calculation: i \langle q_0 | q_0 \rangle = \langle q_0 | [p,q] | q_0 \rangle = \langle q_0 | pq | q_0 \rangle - \langle q_0 | qp | q_0 \rangle = q_0 \langle q_0 | p | q_0 \rangle - q_0 \langle...