# Do you know what this particular unitary operator is?

#### QMrocks

Recall that the unitary operator $exp(\frac{i}{\hbar}aX)$ transform the operator $P_x +a$ to $P_x$.

Now, what is the unitary operator that transform the operator $P_x +aX$ to $P_x$ ??

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#### seratend

QMrocks said:
Recall that the unitary operator $exp(\frac{i}{\hbar}aX)$ transform the operator $P_x +a$ to $P_x$.

Now, what is the unitary operator that transform the operator $P_x +aX$ to $P_x$ ??

you mean P_x to P_x + a

$exp(- \frac{i}{\hbar}aX)$

: )

Seratend.

$exp( \frac{i}{\hbar}aX^2/2)$ is the answer to your question

Last edited:

#### QMrocks

seratend said:
$exp(- \frac{i}{\hbar}aX)$

: )

Seratend.
Nope...........................

#### QMrocks

There is no typo.

#### seratend

QMrocks said:
There is no typo.
See corrected previous post.

Seratend.

#### QMrocks

seratend said:
$exp( \frac{i}{\hbar}aX^2/2)$ is the answer to your question
Thanks. Thats the answer i tempted to throw in too. But i have my doubts..

#### seratend

QMrocks said:
Thanks. Thats the answer i tempted to throw in too. But i have my doubts..
Doubts, why? You just have to calculate.
Hint: try to see what the unitary operator exp(i a(X)) does on the momentum operator.

Seratend.

#### QMrocks

My bad, Seratend. You are absolutely right! Case close :)

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