- #1
qm14
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Homework Statement
State vector :
[itex]| \psi \rangle = \sum_{n = - \infty}^\infty a_n| \psi \rangle [/itex]
where
[itex]a_n= i\sqrt\frac{3}{5}{\frac{i}{4}}^{|n|/2}e^{-in\pi/2}[/itex]
Find the probability of the particle in Nth state.
What is the total probability of the particle in 'N' negative state.
Homework Equations
[itex]|\langle\psi|\psi\rangle| ^2 = 1[/itex]
The Attempt at a Solution
Would the probability of the particle being in Nth state be [itex]|\langle\psi|\psi\rangle| ^2 =
=> |a_n|^2 = [/itex] ?
[itex]a_n*= -i\sqrt\frac{3}{5}{}\frac{1}{4i}^{|n|/2}e^{+in\pi/2}[/itex]
If so here is my working...
[itex] \sum_{n -\infty}^\infty a_n a_n* \delta_{n m} [/itex]
[itex]\sum_{n -\infty}^\infty ( i\sqrt\frac{3}{5}{\frac{i}{4}}^{|n|/2}e^{-in\pi/2} )(-i\sqrt\frac{3}{5}{}\frac{1}{4i}^{|n|/2}e^{+in\pi/2} )[/itex]
[itex] |a_n|^2 = \gamma [/itex] [itex] \sum_{n -\infty}^\infty(1/4)^{|n|}
[/itex]
where [itex] \gamma = 3/5 [/itex]
How do I go around evaluating this summation from -infinity to +ve infinity though the power is |n|.
Evaluating the summation in the range (0,infinty) yields (3/5)+ 0 ...
Thanks.