Volume 11 Issue 7, July 2015

The history of the fierce opposition met by Einstein's theory of relativity in the 1920s teaches us that public controversies about science are not necessarily settled by sound scientific reasoning.

Quantum many-body systems are often so complex as to be intractable. An algorithm that finds the ground state of any one-dimensional quantum system has now been devised, proving that the many-body problem is tractable for quantum spin chains.

The Anderson transition point between localization and diffusion — the mobility edge — has now been directly measured in an ultracold-atom experiment.

A niobium titanite nitride-based superconducting nanodevice — a Cooper-pair transistor — has a remarkably long parity lifetime, exceeding one minute close to absolute zero.

Certain nodes are influential in spreading information — or infection — across a network. But these nodes need not be those with the most connections, and topology can play a key role, as a 2010 paper in Nature Physics established.

High-harmonic spectroscopy is a powerful tool for probing the electronic structure of atoms and molecules in gases. Experiments now show that similar emission from solids has a different origin.

The transition to widespread connectivity in networks is aptly described by concepts borrowed from percolation theory. Attempts to delay the transition with small interventions lead to explosive percolation, with drastic consequences for the system.

In a delayed-choice experiment the decision to measure the particle or wave nature comes after the photon enters the interferometer. An atomic version of the experiment provides the same outcome despite the mass and internal structure of the atoms.

The symmetry of Cooper pairs in iron-based superconductors is an issue under continued investigation. A scanning tunnelling study of Fe(Te,Se) reveals a robust zero-energy bound state, providing evidence for a non-trivial pairing symmetry.

One minute parity lifetimes are reported in a superconducting transistor made of niobium titanite nitride coupled to aluminium contacts even in the presence of small magnetic fields, enabling the braiding of Majorana bound states.

The brightest extragalactic black holes emit X-rays with intensities that are thousands of times greater than those from black holes within our Galaxy. However, optical spectra suggest these different sources may be more similar than once thought.

The mobility edge characterizes the transition from localization to diffusion. This key parameter in Anderson localization was measured for a system of ultracold atoms in a tunable disordered potential created by laser speckles.

Anderson localization has recently attracted renewed interest in strongly correlated quantum systems. Now, local adiabatic manipulations are shown to lead to a nonlocal response, with implications for quantum control in disordered environments.

An algorithm that provably finds the ground state of any one-dimensional quantum system is presented, providing a promising alternative to the widely used, but heuristic, density matrix renormalization group approach.

A unidirectional magnetoresistance observed in bilayer metal films could be used to add directional sensitivity to conventional magnetic sensors based on anisotropic magnetoresistance.

The spin-dependent Seebeck effect converts thermal gradients into spin currents. It is now shown that this effect can be used to drive spin-transfer torques on picosecond timescales using the heat currents created by ultrafast pulses of laser light.

Direct measurement of the exciton binding energy shows that the impressive performance of perovskite solar cells arises from the spontaneous generation of free electrons and holes after light absorption.

A computer based on droplets moving in microfluidic channels requires synchronous manipulation of the droplets. Such synchronous logic is now shown for a system of ferrofluid droplets, with a rotating magnetic field providing the computer clock rate.

Our understanding of how catastrophe propagates in multi-layered networks relies on theories that apply only to infinite systems. Reducing the interconnected networks to a set of decoupled graphs provides a route to probing finite sizes.

A voyage into the unknown.