### Author Topic: Evolution under shift operator using exponential of CommutationSuperoperator  (Read 2117 times)

#### Tak

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• Posts: 3
##### Evolution under shift operator using exponential of CommutationSuperoperator
« on: October 08, 2013, 11:29:47 AM »
Hello,

I would like to use SpinDynamica for analytical product operator calculations. I have some problems to calculate the evolution under a shift operator. The notebook with examples is attached and I am running SDv2.8.2b1 (from Malcolm Levitt).

#### MalcolmHLevitt

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• Posts: 103
##### Re: Evolution under shift operator using exponential of CommutationSuperoperator
« Reply #1 on: October 08, 2013, 12:25:43 PM »
Hi Tak,
thanks. Your calculation is rather strange in form since the complex exponential of a commutation superoperator would normally be calculated for the case of a Hermitian operator, i.e. superoperators of the type Exp[-I CommutationSuperoperator[opI["x"]]] rather than Exp[-I CommutationSuperoperator[opI["+"]]] (note that opI["x"] is Hermitian, while opI["+"] is not).

I suspect that the perceived problems are something to do with your choice of a non-Hermitian operator, although I do not yet know how this works out to give the behaviour you show. It is possible that the behaviour is expected for such an unconventional calculation.

Please verify that you really want to calculate the term shown.

As an additional comment, when posting a bug, please indicate clearly what behaviour you find to be unexpected or wrong. That will save effort on my behalf.

best wishes
malcolm

#### Tak

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• Posts: 3
##### Re: Evolution under shift operator using exponential of CommutationSuperoperator
« Reply #2 on: October 08, 2013, 01:25:51 PM »
Thank you Malcolm,

for your fast response and for pointing out that the calculation is rather strange. I will rethink, if this makes sense at all for my problem and what I finally want to calculate. (Sorry, that was probably rather an NMR than a SpinDynamica question...  )

Best wishes

Tak