Supernovae are the most powerful events known in the Universe. Most frequently a supernova results from the core-collapse of a dying star, and the wealth of physics involved in the process presents a huge computational challenge to those who try to model it. In this issue, Stan Woosley and Thomas Janka guide us through gravitational collapse, convective instability, neutrino emission and energy deposition, gamma-ray bursts and rapid neutron capture. Two complicating factors — the rate of rotation of the star and the presence of magnetic fields — are likely to be key factors in determining its death throes as a supernova.

Review Article by Woosley and Janka

Diamond could be the perfect host for a qubit.

To see a diamond, don't go to a jewellery shop — head for a spintronics or quantum-computation laboratory instead. The spin associated with a nitrogen vacancy centre — an impurity sitting at a vacancy site in the diamond lattice — has a long lifetime and is therefore promising for applications in quantum information processing. Ryan Epstein and colleagues have constructed a room-temperature microscope that is sensitive to the light emitted by a single nitrogen vacancy centre. Moreover, by precisely controlling the magnetic field, they can detect the presence of nearby non-luminescent nitrogen atoms that couple to the nitrogen vacancy centres. These 'dark' spins have an even longer lifetime than the bright spins.

Image courtesy of Russell J. Hemley, Carnegie Institution of Washington.

Letter by Epstein et al. | News and Views by Kennedy

Atoms intercalated between sheets of graphene.

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.

Letter by Weller et al. | Letter by Csányi et al. | News and Views by Klapwijk