Volume 8 Issue 7, July 2012

The bid to host the world's largest, most sensitive radio telescope has ended in a tie.

Single electrons in quantum dots can be disturbed by the apparatus used to measure them. The disturbance can be mediated by incoherent phonons — literally, noise. Engineering acoustic interference could negate these deleterious effects and bring quantum dots closer to becoming a robust quantum technology.

A study shows that controlling link dynamics on a network is distinctly different from controlling the dynamics of its nodes. This development illustrates how ideas from control-systems engineering can help us better understand the organization of complex systems.

Hole-doped cuprate superconductors exhibit an enigmatic state known as the pseudogap state. Mapping the distribution of this state as it evolves in real space with doping indicates that the moment the pseudogap fills the material is when superconductivity emerges — suggesting an intimate connection between the two.

A quantum memory that combines high-efficiency and long lifetime is now demonstrated. Employing a collective excitation, or spin wave, in an ensemble of atoms in a trap improves memory lifetime, while incorporating the trap into an optical ring cavity simultaneously aids higher retrieval efficiency.

You influence a system by measuring it. This back-action is an important consideration when studying tiny structures in which quantum effects play a crucial role. Researchers now show that quantum interference could provide a way to negate back-action in quantum-dot-qubit circuits.

Uranium ruthenium silicide exhibits a discontinuity in its specific heat at 17.5 K. The underlying cause of this anomaly is hotly debated. A first-principles study of high-order correlations in its electronic structure suggests this behaviour is the result of the emergence of rank-5 nematic order.

Scanning tunnelling microscopy images of the evolution of the pseudogap phase of a hole-doped cuprate superconductor suggest that it emerges in localized clusters that grow with increasing doping. Moreover, the eventual coalescence of these clusters coincides with the emergence of superconductivity.

The penetration of a superconducting current from a superconductor into a half-metallic ferromagnet is usually forbidden. Resonances in the conductance spectra of superconductor/half-metal heterostructures suggest this restriction is lifted by the occurrence of unconventional equal-spin Andreev reflection.

Diffraction of matter waves from crystalline structures has long been used to characterize underlying spatial order. The same principle offers a valuable—and potentially non-destructive—tool for probing the strongly correlated phases of ultracold atoms confined to optical lattices.

The extra states sometimes observed in graphene’s quantum Hall characteristics have been presumed to be the result of broken SU(4) symmetry. Magnetotransport measurements of high-quality graphene in a tilted magnetic field finally prove this is indeed the case.

A demonstration of the ability to transmit spin currents over distances of more than one hundred micrometres with an efficiency of up to 75% in graphene grown epitaxially on silicon carbide improves the prospects of graphene-based spintronic devices.

There is growing evidence that quantum coherence enhances energy transfer through individual photosynthetic light-harvesting protein complexes. This idea is now extended to complicated networks of such proteins and chemical reaction centres. A mathematical analysis reveals that coherence lengths up to 5 nm are possible.

Surprisingly little is known about how network dynamics might be controlled, despite extensive research into how they behave. A study of the controllability of network edge dynamics reveals that it differs from that of nodal dynamics, and that real-world networks are easier to control than their random counterparts.