There really is no definite answer to your question. The two species can be maintained simultaneously but a variety of factors will determine that:
The personality of your cat or turtles.
Yes, even turtles have personalities. Some are shy, some enjoy bullying cats, some don't seem to mind cats whatsoever. As for cats, some may be inclined to attack the turtles, some may be fearful of them. Generally for the cats, pond sliders don't do much physical damage, it's the stress their partnership may form. Also, even if the cats don't mind the turtles, some turtles may be stressed from their presence.
The age and size of the turtles and cat.
Larger turtles don't have much to worry about cats. You didn't mention what specific species of sliders you have, but generally females reach between 9-12 inches with males being a few inches smaller. The large males and most females have little to worry from a cat, and the cat probably won't approach them. Since turtles grow slowly, and yours are young, you need to keep and eye out for the turtles because the cat will quickly grow and can become very dangerous to the younger ones.
How you deal with the partnership.
You should notice at least some signs of curiosity, especially from the kitten. If the kitten ever decides to approach the turtles and doesn't get rebuked for it then it's likely to go for them again until they get hurt. At the first few months you get the cat you really have to look out for the cat, with positive and negative feedback the cat can know that you will not be glad if the turtles get hurt. I've seen numerous photos and stories of cats and smaller lizards like bearded dragons getting along, as a matter of fact they would often sleep next to each other!
This relationship can be maintained but there are various factors that come to play here, some of which you have no control over. The only real way to know is to try it out. If you're willing to do so, and the two species don't get along after a period of acclimation, then it's preferable you protect the turtles' enclosure with some sort of fencing the cat can't unlock. I'd also point out that your turtles may be in danger from wild predators as the pool you have for them is on the balcony and is not fenced.