Another BEC is being researched.

I found another article on BECs in Nature (doi:10.1038/nature09378):

Single-atom-resolved fluorescence imaging of an atomic Mott insulator
Jacob F. Sherson1,3,4, Christof Weitenberg1,3, Manuel Endres1, Marc Cheneau1, Immanuel Bloch1,2 & Stefan Kuhr1

1.Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, D-85748 Garching, Germany
2.Ludwig-Maximilians-Universität, Schellingstraße 4/II, D-80799 München, Germany
3.These authors contributed equally to this work.
4.Present address: Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C, Denmark.


Correspondence to: Stefan Kuhr1 Email: stefan.kuhr@mpq.mpg.de


Top of pageAbstractThe reliable detection of single quantum particles has revolutionized the field of quantum optics and quantum information processing. For several years, researchers have aspired to extend such detection possibilities to larger-scale, strongly correlated quantum systems1, 2 in order to record in situ images of a quantum fluid in which each underlying quantum particle is detected. Here we report fluorescence imaging of strongly interacting bosonic Mott insulators in an optical lattice with single-atom and single-site resolution. From our images, we fully reconstruct the atom distribution on the lattice and identify individual excitations with high fidelity. A comparison of the radial density and variance distributions with theory provides a precise in situ temperature and entropy measurement from single images. We observe Mott-insulating plateaus with near-zero entropy and clearly resolve the high-entropy rings separating them, even though their width is of the order of just a single lattice site. Furthermore, we show how a Mott insulator melts with increasing temperature, owing to a proliferation of local defects. The ability to resolve individual lattice sites directly opens up new avenues for the manipulation, analysis and applications of strongly interacting quantum gases on a lattice. For example, one could introduce local perturbations or access regions of high entropy, a crucial requirement for the implementation of novel cooling schemes3.

My Favorite Graphene Joke!

How do you make a hole in graphene without creating a mobius strip?

Answer: By using the absorption of a phonon by an electron in the lower cone of momentum space to raise it to the upper cone leaving a hole. Using brute force to knock a carbon atom out of a benzene ring, i.e., hexagon, leaves a pentagon which looks like a mobius strip in momentum space.


Raman spectroscopy confirms that graphene violates the adiabatic Born–Oppenheimer approximation which is based on separating the motions of electrons and phonons, and considering these as frozen. This is invalid because of the role of hole creation in phonon propagation. It is interesting how you have three types of dark excitons and one light in nanotubes. It is even more interesting to use excitons, i.e., bound electron hole pairs, in bilayer graphene to form a Bose Einstein condensate. I read about plasmons in graphene, but do not know if they really exist.

Phase Transitions in Graphene

Dreaming about graphene is a beautiful thing. The leptons become light and dark excitons. Suspending graphene makes the top and bottom surfaces indistinguishable. You can even invert its handedness. Time reversal symmetry makes single layer graphene almost perfect. But bilayer is great, too. A magnetic field can be applied to change the phase of the excitons in a bilayer, half-filled system to that of a Bose Einstein condensate. When current flows in opposite directions in the two layers, the resistance goes to zero. An oddly quantized vortex binding one zero mode per valley is present, though slightly split due to a mixing of the valleys in the graphene layers. You can also have a phase transition from this coherent excitonic phase to a pair of single-layer fractional Quantum Hall States as a function of layer spacing. There is always something new to read about graphene as one drifts off to sleep.