- #1

Xyius

- 508

- 4

## Homework Statement

Evaluate the following using Ket-Bra notation

a.)[tex]exp[if(A)]=?[/tex]

Where A is a Hermitian operator whose eigenvalues are known.

b.)[tex]\Sigma _{a'}\psi^{*}_{a'}(x') \psi_{a'}(x'')[/tex]

## Homework Equations

None that I can think of, I believe this is all mathematics.

## The Attempt at a Solution

a.) Well I assume if(A) means a function of A multiplied by the imaginary number i. My gut instinct is to simply write this as a Taylor expansion.

[tex]exp[if(A)]=1+if(A)+\frac{(if(A))^2}{2!}+\frac{(if(A))^3}{3!}+...[/tex]

I do not know where to go from here, or if this is the correct approach. It says to use ket-bra notation but I do not see where I could fit that in with this method.

b.) Honestly I have not tried this one yet so I do not wish to receive help on this just yet as I would like to try it for myself, I just put it up here because I am assuming I will have trouble with it when I finish part a.) :p

Can anyone help? :\