Can we do partnership with a person who doesnt exist ??

Not possible. It must be in tangible form

But how would govt know about ? that

During registration, they will verify pan no

Yes you can make an unregistered partnership firm on a stamp paper of Rs 750 and get it notarized, yes you can apply for its PAN and with in 7 working days you will get the PAN also but what if you wish to open a bank account there you need to show your partner, what if you wish to get GST registration then it is mandatory to get aadhaar authentication of all partner, there PAN, photo all needed at time of seeking for registration, in case of Govt Tenders you need both the person to be exist. If the above what are affirmative then you will face many problem else Go For It.