Papers and preprints worth reading, Jan-midFeb 2012 Which recent (i.e. Jan-midFeb 2012) papers and preprint do you consider really worth reading?
References should be followed by a summary saying what is the result and (implicitly or explicitly) why it is important/interesting/insightful/...
One paper per answer (and start from its citation); you can add further but only in the description (e.g. It generalizes the ides of X in [cite]...).
As it is a community wiki - vote whenever you consider a paper good. 
Also - feel free to contribute to other's posts.
See Journal club-like thing for a meta post.
 A: Light-cone-like spreading of correlations in a quantum many-body system reports the first measurements of the speed at which quantum correlations spread in a quantum many-body system. Prior related theoretical works are [2,3,4]. Though the main innovations are plausibly the experimental techniques, I think theorists should be aware of the results.
A: http://arxiv.org/abs/1202.2274
Quantum Einstein Gravity
Martin Reuter, Frank Saueressig
A pedagogical but detailed review of the asymptotic safety program in Quantum Einstein Gravity.
A: http://arxiv.org/abs/1201.4390
The Operator Tensor Formulation of Quantum Theory
Lucien Hardy
A formal but I think pedagogical presentation of a formulation of Quantum Mechanics successfully used by Lucien Hardy. The tensor formulation makes intense use of Penrose’s diagrammatic notation, adapted to quantum operators. The quantum processes are viewed as circuits, in a way which decouples them from the time evolution. Many interesting quantum phenomena become by this visible, so I think this formulation should be part of the toolbox of anyone interested in the foundations of QM.
A: http://prl.aps.org/abstract/PRL/v108/i7/e070402
Procedure for Direct Measurement of General Quantum States Using Weak Measurement
Jeff S. Lundeen and Charles Bamber
Arxiv version: http://arxiv.org/abs/1112.5471
By combining weak and strong measurements on complementary observables, on identically prepared ensembles, the real and complex parts of the uncollapsed wavefunction are obtained. This is a simpler and more direct alternative to Quantum State Tomography, but unlike the latter, it works only with pure states.
A: http://arxiv.org/abs/1201.4276
Dream-land with Classic Higgs field, Dimensional Reduction and all that
D. V. Shirkov
A summary/continuation of the work of D. V. Shirkov and its collaborators in the regularization by dimensional reduction, as an alternative to the Higgs boson in the standard model.
A: http://arxiv.org/abs/1202.0631
Quantum Cheshire Cats
Yakir Aharonov, Sandu Popescu, Paul Skrzypczyk
Another quantum paradox a la Aharonov, a pre and post-selected experiment which separates the photon (cat) from its circular polarization (smile).
