How it would be when we have a physical bitcoin currency note? Do they already exist? If created, will it impact the market growth and loose it's value in the market? Any thoughts?
No, I never ever wish something like that. How silly to think that a virtual and intangible asset like bitcoin will also have its own paper money or coin
. Now, if it happens (though it's impossible), what would be its great difference compare to fiat money? Nothing anymore of course. Btc's or any crypto's uniqueness by means of being virtual yet still have a value makes them special, and I think it would be better if it will remains 
. Anyway, there are still existing tangible coins such as btc, eth, ltc or even doge also but it has no value and only intended to made for memorabilias.