Letters in 2017

Mechanism-based metamaterials leverage geometric design to control deformations — a strategy that works well on small scales. But the discovery of a characteristic length scale suggests that the underlying mechanism is distorted for larger systems.

The photoactive properties of microalgae are well documented when it comes to photosynthesis and motility. But it seems their adhesion to surfaces can also be manipulated with light, which may serve to optimize their photoactive functionality.

Combining micrometre-sized mechanical resonators with superconducting quantum circuits, quantum information encoded with photons now can be converted to the motion of a macroscopic object.

α-RuCl₃ has recently attracted great interest as a possible experimental realization of the Kitaev model. Neutron scattering measurements of a single crystal of this material reveal signatures of Majorana excitations, consistent with Kitaev’s predictions.

The demonstration of a direct correlation between an optical stimulus and the biological function of a photoreceptor in living brain tissue charts the course for designing tailored pulses to control molecular dynamics in vivo.

Particles in strongly coupled plasmas behave collectively as in liquids, with additional long-range collisions. Experimental evidence is provided that fluctuation theorems obeyed by liquid are also valid for strongly coupled dusty plasmas.

When molten tin droplets impact clean substrates, they either stick or spontaneously detach depending on the substrate temperature. Competition between heat extraction and fluidity controls this behaviour, forgoing the need for surface treatment.

Traditionally quantum state tomography is used to characterize a quantum state, but it becomes exponentially hard with the system size. An alternative technique, matrix product state tomography, is shown to work well in practical situations.

Magneto-optical trapping and sub-Doppler cooling of atoms has been instrumental for research in ultracold atomic physics. This regime has now been reached for a molecular species, CaF.

Understanding crack formation is important for improving the mechanical performance of materials. A new theory is now presented for the description of cracks propagating at high speeds, with elastic nonlinearity as the underlying principle.

Graphene systems are clean platforms for studying electron–electron (e–e) collisions. Electron transport in graphene constrictions is now found to behave anomalously due to e–e interactions: conductance values exceed the maximum free-electron value.

Experimental signatures of a Berry phase for composite fermions in the fractional quantum Hall effect provide support for the predictions that these composite fermions are Dirac particles.

Semiconductor nanowires with superconducting leads are considered promising for quantum computation. The current–phase relation is systematically explored in gate-tunable InAs Josephson junctions, and is shown to provide a clean handle for characterizing the transport properties of these structures.

Physical rotation can create fictitious magnetic fields, a phenomenon that stems from Larmor's theorem. The effect on a nuclear spin ensemble was measured using the spin–echo of nitrogen–vacancy centres in rapidly spinning diamond. Interestingly, the rotationally induced magnetic fields can cancel a conventional magnetic field for the nuclear spins.

The way two liquids interact depends on how miscible they are. A remarkable phenomenon involving two miscible liquids is now reported: placing a drop of isopropanol on a water surface results in a Marangoni flow, and a static lens in the middle.

The pseudogap is an elusive state that is believed to play an important role in the mechanism for high-temperature superconductivity. A torque-magnetometry study of YBCO reveals that its onset is associated with a second-order nematic transition.

The anomalous Nernst effect is usually associated with ferromagnets — enabling a temperature gradient to generate a transverse electric field — but the Berry curvature associated with Weyl points can drive this phenomenon in chiral antiferromagnets.

Water droplets skid across hot surfaces, hovering imperceptibly as they undergo rapid vaporization. Elastic solids are now shown to exhibit a variant of this behaviour, engaging in sustained bouncing by coupling vapour release to elastic deformation.

A hidden stripe-type charge ordering in multilayer iron selenide films on strontium titanate, resembling that in high-temperature cuprate superconductors, could help to explain the complex behaviour of this unusual iron-based superconductor.

A detailed neutron scattering study of the Shastry–Sutherland material SrCu₂(BO₃)₂ verifies the existence of a 4-spin plaquette singlet phase in this system.