Hello, I am new to Easyspin, so I got a little stuck.
My task is to simulate spin evolution of two spins simultaneously excited by slightly different m.w. pulses.
I decided to begin with the easiest setup: two equivalent 1/2 spins (same Zeeman frequency, no interaction). They are both simultaneously excited with two pulses with the identical IQ. However, each pulse excites only one of the spins.
There is an example in the User Guide for Spidyan that seems to be the one I need (I've slightly modified it for my purposes):
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Pulse.IQ = real(mwPulse) + 1i*imag(mwPulse);
Opt.ExcOperator{1} = sop([1/2 1/2],'xe') + 1i*sop([1/2 1/2],'ex');
Exp.mwPolarization = 'circular';
Exp.Sequence = {Pulse};
spidyan(Sys,Exp,Opt)
Unfortunately, it did not work for me: in my script only the first spin was flipped, while the other remained unchanged.
Moreover, after analysis I've found some strange questions I can't really answer
1)The example commentary states that the first pulse is excited by the real part of the IQ, while the second pulse is excited by the imaginary part. However, in my case the flip angle if the first spin depends both on the real and imaginary parts.
2) If I remove the second excitation operator and leave it as
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Opt.ExcOperator{1} = sop([1/2 1/2],'xe')it would only excite the first spin, which makes sense. At the same time, if I make this operator imaginary, such as
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Opt.ExcOperator{1} = 1i*sop([1/2 1/2],'xe')it would instead excite the second spin in a weird way (with <Sz> going below -1).
I don't completely understand the way excitation operators act in Easyspin, so I am probably missing something.