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Graphite was first known as 'black lead', and the resemblance doesn't stop there - both lead and graphite are superconductors. Thomas Weller and co-authors have intercalated ytterbium or calcium atoms between graphene sheets and discovered superconductivity in these materials below 6.5 K and 11.5 K, respectively. Strangely, pushing the graphene layers further apart with these intercalant atoms makes the system more electronically isotropic. This work has generated a lot of theoretical activity, such as that by Gábor Csányi and collaborators. Their electronic structure calculations show that the electrons introduced into graphite through Yb and Ca doping do not behave conventionally. Instead of the graphene layers, they seem to prefer the void between the sheets. This would explain the increased isotropy, for example.
Quantum information science has brought us novel means of calculation and communication. But could its theorems hold the key to understanding the quantum world at its most profound level? Do the truly fundamental laws of nature concern — not waves and particles — but information?
Although recent years have seen substantial improvements in the perfomance of photonic-crystal cavities, their design has been a rather hit and miss affair. By turning around the general approach to cavity design through the use of Bloch waves, an important avenue to the discovery of optimal cavity geometries could be opened.
Physical phenomena associated with a quantum critical point are different from their classical counterpart in many ways. For one thing, the effects of quantum criticality might in some cases be observed far away, at unexpectedly high temperatures.
Crackling noise emitted in systems as diverse as candy wrappers and earthquakes show strikingly similar behaviour, but how it is influenced by the details of these systems is unclear. A study that identifies the microscopic origin of unexplained asymmetries in the noise emitted by a magnet could provide some answers.
There is good reason to suppose that the Universe has more than three spatial dimensions. The first dedicated search for warped extra dimensions has drawn a blank, but hopes are high for the future.
The discovery of a superconductor is always exciting, but particularly so when the material is a common stationery item and the superconductivity is possibly unconventional.
The wave nature of matter is well established for isolated particles, from electrons to molecules. Now experiment reveals that even deeply buried core-shell electrons in a diatomic molecule can emit coherently.
Wet sand is more stable than dry sand, but exactly how this greater stability arises has been the subject of considerable discussion. Conflicting ideas are now unified by a hybrid theory that considers both surface and bulk properties of a sandpile.