Couple of things are associated with your post. First let me write about legal requirement. If you wish to quit your employment then please check the provisions of the separation from the company that are mentioned in the Appointment letter (not offer letter). Generally, condition of notice period during the probation is not rigid. Therefore, if you wish to leave, then better leave during probation itself.
What I have written above is legal part. Now coming to the question of career. Unarguably, Infosys is a branded company. I do not know the nature of your work, nevertheless, whatever you are doing now, you must have been apprised about it well before joining. Therefore, why grouch now on your conscious decision that you have taken earlier? Why you feel that there are no opportunities in Infosys that you would know best. Going further, as far as motivation is concerned, why you want external motivation? You keep yourself motivated. If environment Infosys cannot motivate you then I doubt how companies are there in India that can motivate you!
Most of the job applicants always vie to get into branded company. Please be aware that every single day that you pass in this company adds value to your CV. Secondly, whatever the job that you may do, superior quality of the colleagues also matters. You can identify colleagues who wish to have intellectual exchanges and start having discussion with them. Other than these branded companies, you may not be able to get colleagues of this kind.
You may approach someone who knows about your job and take help in preparing your career plan. Identify what are the opportunities in Infosys itself. You may do relevant courses to get internal placement. Go and talk to HR of your company. Find out what they suggest on the career advancement.
You may take any decision however, please make sure that out of overly eagerness, you do not rue in future.
From India, Bangalore