Given the nature of my job I am not sure whether workplace.SE is a better option of if academia.SE is where I should post this question.
I am currently a postdoctoral associate at a lab in France. I was hired in May 2014, on a 2 year contract, after I met a certain set of requirements (knowledge of a certain sub-topic in applied physics). My core responsibilities were the development of physical concepts to drive the design of a certain automotive technology and create a knowledge-base for the same.
9 months or so in, I found that all I have been doing for this duration is debug a "spaghetti" computer code developed by my supervisor. This computer code is related to the technology in question but it does not involve developing physical concepts. It has to do with correcting bugs in a code that has never been documented, no FAQs exist and neither is there a "Help manual".
It suffices to say that my job has lacked professional development entirely as all I have done for a large part of the year is debug code and NOT develop physical concepts as advertised initially.
I would like to resign from my position for lack of professional development. Yes, I have received a job offer (pending employment visa requirements) as a faculty at a US university. The employment visa notwithstanding, I don't think continuing to ruminate in my current position is a healthy option (personally and in terms of future career growth).
How should I go about my resignation in a professional manner with minimal backlash on my career (don't want to be seen as a quitter)? What are the key points I should make? Should I provide a notice period? Also, my contract doesn't have any clause of a notice period. I am not asking for a resignation letter template as the internet is flooded with them.