Scientists claim to have gotten below absolute zero. Source
I'm a little late in posting about this, but some scientists have claimed that they managed to get a quantum gas below absolute zero, the theoretical lowest temperature. Understanding exactly what they mean by this is difficult, and a lot of that is because the reporting of the phenomenon has been misleading. The "negative Kelvin" temperature that these scientists observed was an inversion in the energy distribution of the particles they were studying, which would indicate a negative Kelvin temperature. Now, it is important to note that zero Kelvin corresponds to a particle having absolutely no energy at all. Given that, it seems like the scientists are indicating that they have somehow achieved negative energy, which is not the case.
I would recommend reading this article from Nature.com, it's very informative.