You can get sharp, crisp photos with either natural or artificial light....it doesn't really matter. What does matter is how much light you have, and thus the exposure settings you can use.
For example, most artificial light (in buildings, houses etc) is actually quite dark...in terms of photography. So many people find that photos in these scenarios aren't as sharp as they would like because they are forced to use a slower shutter speed.
Bright daylight, on the other hand, may allow for faster shutter speeds, which will give you sharper photos.
You can use artificial light (if it's bright enough) to give you faster shutter speeds...or you can use flash/strobe type lighting, which is so short, that it freezes most movement.
As mentioned, using good quality lenses and nailing your focus is key to sharp shots. In these shots, they may also look sharper because of the shallow DOF, which is leaving the subject in focus, while throwing the background out of focus.