If you have some Hamiltonian represented by a 2x2 matrix(adsbygoogle = window.adsbygoogle || []).push({});

## H = \left(

\begin{array}{cc}

0 & \Delta \\

\Delta & 0

\end{array}

\right) ##

And you want to use the time evolution operator

## U = \exp ( - \frac{i}{\hbar} H t ) ##

it says that

## U = \exp (- \frac{i \Delta}{\hbar} t) ##

Why is this?

How did the ##\Delta## get out?

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# Homework Help: Time evolution operator

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