We recently made the first observation of Hawking radiation in any system. We created an analogue black hole in an atomic Bose-Einstein condensate. Both an outer event horizon and an inner horizon were present, in analogy with a charged black hole. This configuration, in combination with the superluminal dispersion relation of the condensate, resulted in self-amplifying Hawking radiation. That is to say, the Hawking radiation reflected from the inner horizon, returned to the outer horizon, and caused additional Hawking radiation.
Phonons and Correlations
This area of research investigates the basic microscopic properties of an ultracold bose gas. The studies were part of the effort to observe Hawking radiation. However, the observations are rather interesting in themselves.
Josephson effect in a Bose-Einstein condensate
The Josephson effect was first discovered in a system of two superconductors separated by a tunneling barrier. In the AC Josephson effect, a constant voltage is applied between the two superconductors. This results in an oscillating tunneling current through the barrier, with a frequency proportional to the applied voltage. Since the proportionality constant involves fundamental constants only, the AC Josephson effect serves as the voltage standard.
In situ optical lattice
The study of optical lattices is one of the most active areas of ultracold atom research. An optical lattice consists of a standing wave light field which creates a periodic potential for ultracold atoms. The lattice can be used for simulating condensed matter systems or even gauge theories.
Oscillating soliton/vortex ring
The matter-wave interference between two initially-separated Bose-Einstein condensates was a landmark observation, demonstrating phase-coherence. The collisional energy of the two condensates was sufficient that interactions between atoms could be neglected. But what happens when the two condensates are separated by a very small distance, on the order of one healing length?