# How to Solve this Integral

1. Jun 10, 2016

### Muthumanimaran

1. The problem statement, all variables and given/known data
I am currently doing a problem in Quantum optics, specifically the problem of finding Wigner Function for Number states or Fock states. I am actually did the problem in a different way and found that Wigner function for Number states is proportional to product of error function and Laguerre polynomials, now I finding the Wigner function from P-Glauber Sudarshan Function, where I encountered this Integral,

$$\frac{2 exp(|α|^2)} {π^3 n!}\ ∫ \frac{exp(-|β|^2-4|α||β|)}{π^2*n!}\ \frac{∂^(2n)}{∂β^n∂(β*)^n}\ δ^2(β) d^2β$$

δ(β) is dirac delta function and α,β are complex
3. The attempt at a solution
I tried the solve the integral but shifting the index and got
$$\frac{2(-1)^n (4)^(2n) exp(-|α|^2) |α|^(2n)}{π^3 n!}\$$

Last edited: Jun 10, 2016
2. Jun 10, 2016

### Staff: Mentor

While I don't know the answer here, I was thinking what if you reversed your thinking and tried differentiating the Laguerre polynomial and see if you can reformulate it into the integrand you have. It might give you insight on how to do the integral.