Volume 17 Issue 5, May 2021

Passing a supercurrent through a topological material can highlight the existence of higher-order boundary states, and may lead to applications in topological superconductivity.

The virtual photons that are exchanged when a free-electron vortex beam interacts with a nanoscopic target unlock an explicit connection between polarized optical spectroscopy and the inelastic scattering of scalar electron waves.

A quantum dot has been used to detect a single excitation among the tens of thousands of atomic nuclear spins comprising it. This result is an important step towards treating nuclear spins as a quantum memory rather than a troublesome source of noise.

The short lifetime of light-induced superconductivity prevents the measurement of its transport properties. Encouraging this state to stay a little longer in K₃C₆₀ allows the observation of vanishing electrical resistance.

Recent advances in spectroscopy give access to the decay time of excitations in disordered insulating silicon close to the metal–insulator transition, revealing similarities to high-temperature cuprate superconductors.

SARS, MERS and now SARS-CoV-2 are unlikely to be the last emerging infections we face during our lifetimes. Tracing contacts both forward and backward through our heterogeneous populations will prove essential to future response strategies.

Starting from a strongly correlated state, with highly non-Gaussian correlations, a Gaussian state can emerge dynamically over time. Experiments with ultracold atoms show how the mixing between phase and density fluctuations plays the crucial role.

Wavefront shaping can reduce uncertainties due to measurement noise through disordered media—key to many imaging applications. Optimal precision can be achieved using light fields that are eigenstates of an operator related to the medium’s scattering matrix.

Laser spectroscopy can resolve vibrational transitions of molecular hydrogen ions without Doppler broadening when these are trapped within a cluster of laser-cooled atomic ions.

High-resolution magnetometry shows that the shape of domain walls in Cr₂O₃ is determined by the energetic cost of their surface area. The walls behave like elastic surfaces that avoid thicker parts of the sample where they would need to be larger.

Cells exploit protein pattern formation to perform key processes, and do so while undergoing major shape changes. Experiments and theory together reveal a shape-adaptation mechanism capable of controlling protein dynamics even as the cell deforms.

A single excitation in a semiconductor nuclear spin ensemble is detected with parts-per-million accuracy using the coupling between the ensemble and an electron-spin quantum dot.

By exploiting polarization entanglement between photons, quantum holography can circumvent the need for first-order coherence that is vital to classical holography.

The functionality of electron energy loss spectroscopy can be extended to include a polarization analogue constructed via the dipole transition vector between two electronic states, bringing it closer to its optical counterpart.

A pair of strongly coupled photonic microresonators shows nonlinear emergent behaviour, which can be understood by incorporating interactions in the theoretical description of nonlinear optical systems.

Evidence for light-induced superconductivity in K₃C₆₀ was limited to optical methods due to the short lifetime of the phase. Extending the lifetime from picoseconds to nanoseconds now allows measurement of its negligible electrical resistance.

A structure of monolayer and bilayer graphene with a small twist between them shows correlated insulating states that can be tuned by changing the twist angle or applying an electric field.

The combination of disorder and strong interactions makes it hard to understand the nature of doped silicon’s insulating phase. State-of-the-art spectroscopy measurements show marginal electronic behaviour reminiscent of what is seen in the cuprates.

Topological materials are characterized by the topological invariants of filled bands, which cannot be used for bosonic systems. Instead, their topological invariants can be found via the transition from bound to leaky modes in photonic lattices.

X-ray pulses with low divergences are produced in a laser-wakefield accelerator by focusing electron bunches in a dense passive plasma lens.

The ability to perform multiple tasks simultaneously is a key characteristic of parallel architectures. Using methods from statistical physics, this study provides analytical results that quantify the limitations of processing capacity for different types of tasks in neural networks.

Contact tracing is key to epidemic control, but network analysis now suggests that whom you infect may not be as pertinent a question as who infected you. Biases due to contact heterogeneity reveal the efficacy of backward over forward tracing.

As the namesake of a variety of constants, distributions and equations, Ludwig Boltzmann has earned his place in the physics hall of fame. But as Ankita Anirban reveals, he cannot take sole credit for the most famous constant bearing his name.