Volume 9 Issue 9, September 2013

A microscopic one-photon subsystem can be entangled with a macroscopic subsystem of thousands of photons: such hybrid micro–macro entanglement, now efficiently produced and verified, should be useful for quantum metrology and for fundamental tests of quantum mechanics.

The role that quasi-bound spins play in the '0.7 anomaly' is controversial. One study suggests that two or more quasi-bound spins may be involved; another advocates that the 0.7 anomaly is a density-of-states effect, needing neither a quasi-bound spin nor spontaneous spin polarization.

A relativistic electron beam travelling on an undulating path interacts with a laser and emits light carrying orbital angular momentum. The wavelengths of these bright twisted-light beams can go down to those of hard X-rays.

An electrically controllable spin–orbit interaction at the surface of transition-metal dichalcogenides highlights the wealth of unexpected physics that two-dimensional systems can offer.

High-resolution imaging of neuronal networks reveals that spontaneous bursts of collective activity are a consequence of an implosive concentration of noise.

A simulation study of a model that mimics certain colloidal particles reveals a surprising low-temperature triumph of entropy, whereby the liquid state persists down to zero temperature.

The significance of 'stripes' in certain high-temperature superconductors has been hotly debated for decades. Now a consensus is emerging that there may, in fact, be two networks of different stripes in which shape resonances play a key role in the superconductivity.

Distinguishing between different sources of noise in quantum dots could help to develop single-photon devices that are suitable for long-range entanglement.

Schrodinger’s cat paradox embodies the open question of whether quantum effects can survive at macroscopic scales. A quantum optics experiment explores this question by creating entanglement between a microscopic and a macroscopic system.

Does quantum theory still apply at macroscopic scales? Looking for new insights into this open problem, an experiment in the spirit of Schroedinger’s cat gedanken experiment investigates the entanglement between microscopic and macroscopic domains.

The interaction between light and a relativistic electron beam can be used to generate optical vortices in a free electron laser, providing a way to engineer bright orbital angular momentum light at shorter X-ray wavelengths.

Patchy colloidal systems consist of particles with attractive patches on them. If the bonds between particles are allowed to be flexible, a colloidal liquid state may be observed as the system approaches zero temperature.

Experimentally verifying that quantum states are indeed entangled is not always straightforward. With the recently proposed device-independent entanglement witnesses, genuine multiparticle entanglement of six ions has now been demonstrated.

A magnetic field can lift the spin degeneracy of electrons. This Zeeman effect is an important route to generating the spin polarization required for spintronics. It is now shown that such polarization can also be achieved without the need for magnetism. The unique crystal symmetry of tungsten selenide creates a Zeeman-like effect when a monolayer of the material is exposed to an external electric field.

Charge noise and spin noise lead to decoherence of the state of a quantum dot. A fast spectroscopic technique based on resonance fluorescence can distinguish between these two deleterious effects, enabling a better understanding of how to minimize their influence.

A Wigner molecule—a localized pair of interacting electrons—is now created in a carbon nanotube. The high-quality, electronically pristine tubes enable a full characterization of the energy spectrum, laying the groundwork for future studies of interacting fermion systems in one and two dimensions.

Neuronal networks can spontaneously exhibit periodic bursts of collective activity. High-resolution calcium imaging and computer modelling of in vitro cultures now reveal that this behaviour is a consequence of noise focusing—an implosive concentration of spontaneous activity due to the interplay between network topology and intrinsic neuronal dynamics.

A study of an actomyosin active gel now demonstrates the importance of the crosslinking density of actin polymers in enabling myosin motors to internally drive contraction and rupture the network into clusters. These results could help us to better understand the role of the cytoskeleton in cell division and tissue morphogenesis.