There are two red buttons here. You see a weighted storage cube on a platform, but you'll need a second one to open the chamber lock. The second one is in the pit on the far wall. create a blue portal under the one in the pit to make it fall out of the orange portal. Then make a blue portal on a wall on your level to retrieve that cube and put it on a button.
Finally, go through the blue portal so you end up on the platform where the orange portal is. Create a blue portal on the wall behind the other platform, and go through the orange portal to get the second cube. Put it on the other red button and go through the chamber lock.
The computer at this point admits that she was totally lying when she said that she would not monitor the test chamber.
If you look around you'll see that there's an orange portal in the room above you, so just make a blue portal anywhere to go through and reach the elevator to the next chamber.