That's ridiculous. They can't give you "48 hours notice" more than two weeks ahead of time! What would keep them from simply saying in the lease, "this is 48-hour notice that we will be coming into your apartment at random times for the next two years"??
Tell them you do not consider that 48-hours notice, that you object to their inability to properly predict when they are going to be going inside your private residence, and that you would like someone to call you the day before they plan to actually go in. Otherwise, just leave your burglar alarm set, which you should anyway, and let them explain to the police why they're inside your apartment without your permission.
The REASON they need to give notice is so that you can BE there, if you choose. I would NEVER let anyone inside my private residence without being present. Just because they own the apartment doesn't mean they have any right to enter it while you're renting it. You are in possession. It would be like renting a car and wondering if the company will come get it without telling you, because it's "theirs".
State laws vary, but tenants can certainly sue for return of rent when a landlord violates the tenant's inherent right of "quiet enjoyment" of the rented premises.