Research articles

Active nematics refers to systems made of a collection of elongated units, each of which consumes ambient or stored energy in order to move. The authors experimentally and numerically study an active nematic system in confinement finding a defect-free regime of shear flow, and defect nucleation under certain boundary conditions, highlighting the importance of topological defects in controlling confined active flows.

Quantum simulation is a crucial tool in areas where classical computers are inefficient. In this work, the authors use a Nuclear Magnetic Resonance quantum simulator to simulate the local dynamics of quantum spacetime as an attempt to exploit quantum information to study loop quantum gravity.

Quantum heat engines hold potential to achieve efficiencies set by the Carnot limit, however loss of energy between quasiparticles and their environment prevents experimental realisation. Here, the authors propose a model to control this heat flow using chirped laser pulses.

The ability of modern society to move towards quantum communications is dependent on the capacity to realize quantum networks with the ability to securely transmit and share information over long distance and among multiple users. The authors propose a protocol for a scalable quantum network made of modules each consisting of continuous-variable measurement-device independent applied to quantum key distribution, allowing to perform secure quantum conferencing among an arbitrary number of users.

Photoacoustic imaging of colloidal nanosystems is a useful tool for biological applications, yet current models of the photo-induced thermal processes contain un-physical assumptions. Here, the authors propose a model capable of disentangling the role of the nanoparticle, shell, surrounding material, and laser pulse properties.

Non-crystalline, amorphous materials are commonly known to exhibit a characteristic local ordering. Here, the authors report a new material prepared by pulsed electrodeposition showing the co-existence of liquid and solid-like amorphous phases, which gives rise to enhanced thermal stability and plasticity.

Light-matter interactions can be used to induce a superconducting-like state in some cuprate superconductors at temperatures above the expected transition temperature. Here, the authors provide time and angle resolved spectroscopic evidence to suggest that photo induced superconductivity can also be achieved in Fe-based superconductors

Finding novel ways of harvesting energy is of fundamental importance in an energy-hungry world. The authors propose a “spin engine” with the potential experimental ability to generate electrical power at room temperature by harvesting the thermal energy of paramagnetic centers using spintronics.

Some layered two-dimensional systems exhibit topologically stable helices in the form of planar magnetic domain walls, which hold potential for all-spin-based technologies. Here, the authors investigate domain walls in rare earth systems and find topologically stable helical ground states which coexist with superspin-glass-like ordering.

Quantum photonics investigates how a controlled number of photons can be used to achieve information processing beyond classical constraints. Here, the authors use optically active defects in hexagonal boron nitride as way to achieve control of photon emission using surface acoustic waves.

Graphene is a low dimensional material with a high surface area and so it is expected to be useful for ultra-sensitive sensors with a range of different applications. Here, the authors use graphene nanorings to detect the rotation of hydrogen molecules in the terahertz region.

Control of composition within domains and at the interfaces between domains, within organic photovoltaic blend devices, is a key aspect of performance. Using neutron reflectivity experiments on model polymer/small molecule bilayers, the authors measure layer composition and interfacial width following thermal annealing, and examine the applicability of equilibrium thermodynamic theory for quantification of behaviour as a function of polymer molecular weight.

Weyl semimetals are a class of crystalline materials whose electronic band structure exhibits topologically protected degeneracy points, known as Weyl points. Here, the authors demonstrate both theoretically and experimentally that Weyl points can also be present in the magnetic-field dependent spectrum of a double quantum dot system, enjoying a similar topological protection.

Doping of 2D semiconductors by electron acceptor or donor molecules has been suggested as a method to optimize their properties for electronic devices. Here, the authors identify three distinct charge transfer mechanisms that depend on the substrate and yield different doping efficiencies.

The study of electronic structure of new materials has benefited from more widely available angle-resolved photoelectron spectroscopy (ARPES) at synchrotron sources, but hard X-ray ARPES, capable of mapping at a depth of some tens nanometres is still of limited access. The authors report on a method to obtain bulk electronic structure using hard X-rays ARPES combined with an effective data processing background removal strategy capable of revealing the valence band electronic dispersion of metal and semiconductor surfaces.

Quantum phenomena can often be explored in a more accessible way by so called quantum analogues, making its understanding and applications more achievable. The authors experimentally realise acoustic Bell states by superposition of coupled 1D elastic waveguides, which allows them to explore a section of the Bell’s state Hilbert space by tuning the complex amplitude coefficients, opening options to exploring quantum entanglement with a classical equivalent from phononics.

The development of photonics and plasmonics has seen electromagnetic evanescent waves being used for diverse applications from trapping small particles to illumination in biological applications. As an equivalent to the optics counterpart, the authors report on the generation of an acoustic evanescent Bessel field for acoustofluidic applications that only requires a single piezoelectric element in a sub-wavelength resonant cavity and that can be used to attract or repel particles and cells using acoustic radiation force.

The design and application of oil-repellent surfaces has attracted much attention, with polyzwitterionic brushes showing the desirable ability to repel oil under water. Using reflection interference contrast microscopy, the authors show that an oil droplet ‘hydroplanes’ over a thin water film, resulting in superior oil-repellency in a surface covered with artificial polyzwitterionic brushes.

Bolometers, a type of cryogenic detectors, are extensively used for astronomical applications but new technologies offer the possibility to lower the temperature they operate at in order to increase their sensitivity. The authors present the experimental realisation of a Cold-Electron Bolometer based on strong on-chip electron self-cooling in which the electrons of the sensing element are refrigerated by superconductor tunnel junctions opening the door to the use of more cost effective devices for space missions.

Soft porous crystals (SPC) are a class of materials widely known for their counterintuitive properties such as negative thermal expansion and negative gas absorption. The authors present a semi-analytical thermodynamic analysis on the conditions required for negative gas adsorption as well as its correlation with pressure-induced breathing in SPCs.