Volume 11 Issue 4, April 2015

New quantum algorithms promise an exponential speed-up for machine learning, clustering and finding patterns in big data. But to achieve a real speed-up, we need to delve into the details.

Research in quantum optics has already led to commercial technologies, but the gap between the lab and market products is still large. Looking from the industrial side, one can see ways of bridging this gap.

Odd-denominator fractional quantum Hall states are routinely observed in high-mobility gallium arsenide heterostructures. Now, a 5/2 state has been observed in an oxide heterostructure — an unexpected state in an unexpected material.

The photons that make up visible light are indivisible. But certain organic materials can use singlet fission to divide the energy from one photon equally between two molecules. Experiments now reveal the molecular dynamics behind this phenomenon.

Selective evaporation of one component from a mixture is a common process, but in the case of ultracold atomic gases, distillation is more complex.

Photons emitted by extragalactic sources provide an opportunity to test quantum gravity effects that modify the speed of light in vacuum. Studying the arrival times of these cosmic messengers further constrains the energy scales involved.

A recent experiment has provided tantalizing evidence in favour of the elusive 'giant pairing vibration' — an exotic excitation of the atomic nucleus.

A 2006 Nature Physics paper reported phonons in a one-dimensional crystal of aqueous droplets traversing a laminar oil flow — putting microfluidics on the map as a tool for unravelling the mechanisms behind regularity in thermodynamically open systems.

The discovery of spin-triplet Cooper pairs at superconductor/ferromagnet interfaces provides a route for combining superconducting and magnetic orders. Recent advances and challenges in the field of superconducting spintronics are now reviewed.

An experiment reveals the dynamics of singly and doubly occupied sites in an atomic Bose gas in a one-dimensional optical lattice, which may provide a better understanding of thermalization and quantum correlations in many-body systems.

A comprehensive experimental investigation of a PrPtAl single crystal concludes that it displays modulated magnetic order driven by quantum critical phenomena.

A theoretical and experimental study reveals the relation between charge density waves and orbital textures for different stackings in a two-dimensional layered material.

Josephson vortices are circulating supercurrents with an inner structure that is challenging to probe experimentally. Scanning tunnelling microscopy now shows that such vortices contain non-superconducting cores.

Topologically protected states with a natural helicity are shown to form at step edges, which can be created with subnanometre precision in a weak topological insulator using atomic force microscopy.

Gamma-ray bursts can be used to test for the presence of spacetime foam—postulated in theories of quantum gravity. Quantum fluctuations would cause the photon speeds to vary, leading to ‘fuzziness’ and, consequently, Lorentz invariance violation.

The fractional quantum Hall effect, occurring for rational Landau-level filling factors, is commonly observed in GaAs heterostructures. Now, unusual even-denominator fractional quantum Hall states are reported for an oxide 2D electron system.

A vibrational wavepacket generated in a spin singlet is shown to be transferable to spin triplets during singlet fission in organic semiconductors, providing a link between multi-molecular singlet fission and single-molecular internal conversion.

Rogue waves in a sea of photons can localize light beyond the diffraction limit, but their rarity makes them difficult to study. These events can now be controllably triggered in a photonic crystal resonator.

A wealth of possibilities.