Tomorrow’s much anticipated quantum computers, exotic as they may be, will require complex classical hardware for their control and operation. For solid-state quantum processors, the authors propose an efficient scheme for executing a quantum algorithm via a multicomponent classical interface. These components, which include cryogenic classical logic, are assembled to demonstrate control of a quantum-dot qubit. Thus, when the new wave of hardware finally arrives, we will be ready–and able–to use it.

Laser-induced forward transfer (LIFT) allows for high-resolution three-dimensional printing of e.g. small metal droplets, for which inkjet printing is not an option. Although the technique is almost 30 years old, a detailed understanding of its physics has been lacking. The authors observe and explain the high-speed mechanisms behind the ejection of pure metal microdrops during LIFT, which further allows parameter optimization for a particular job.

One approach to quantum computing seeks to exploit ultralow-power optical pulses working in the few-photon regime. The authors propose an all-microwave flip-flop device, built from superconducting components and controlled by single photon pulses, with memory states driven at the 20-attowatt power level. This device does not rely on metastable atomic states, but instead features memory states with longer lifetimes than those of its individual components.

Countless applications rely on the electrical or optical properties of semiconductors, so understanding those properties is the key to continued success. The authors develop a detailed physical model of vacancy-mediated diffusion and use it to describe Al diffusion in ZnO successfully. This model couples impurity diffusion to the material’s intrinsic defect properties, allowing for their determination from defect-concentration profiles. While ZnO is an interesting material in its own right, the model is still more significant, as it may be adapted for any system in which vacancy-mediated diffusion is dominant.

Graphene’s unique material properties enable the production of ultralightweight mechanical resonators that could yield significant progress in nanomechanical mass sensing and quantum optomechanics. The key to unlocking this potential is the precise measurement of a resonator’s oscillations. The authors use high-Q optical cavities to read out this motion with state-of-the-art precision and bandwidth.

“Clean” dewetting, in which a liquid completely withdraws from a surface and leaves no trace, is very desirable in immersion lithography and solution processing of organic electronics. To this end, the authors study thermocapillary deformation by shining an infrared laser on thin liquid films on moving substrates. On a partially wettable substrate the film tends to become unstable, and for certain ranges of laser power and substrate speed it ruptures in a single location and subsequently dewets, without leaving residual droplets.

Sources of terahertz radiation (between the far infrared and microwave frequencies) are in high demand for a host of applications. The authors report on what is essentially a “T-ray flashlight”, a compact and portable source of tunable, continuous terahertz light, employing a stack of intrinsic Josephson junctions in a cuprate superconductor as the emitter. This economical and convenient device can be driven by one everyday 1.5-V battery, and should facilitate airport security, nondestructive evaluation, and remote detection of trace gases, among other applications.

Viscous fluids are used as vibration dampers in applications ranging from isolation tables to cars; they are well understood and easy to engineer. An attractive alternative proposed for turbines, medical applications, and spacecraft is to use granular materials as dampers: Unlike fluids, they are nearly independent of temperature, can operate in harsh environments, and provide damping with no fixed anchor. Unfortunately, there are no design rules for these dampers, so the present paper characterizes effects of amplitude and frequency of oscillation on generic granular dampers. The authors determine broad operating ranges and find that, unlike their fluid counterparts, granular dampers strongly suppress higher-order dynamic resonances.

Organic light-emitting diodes (OLEDs) could be the thin-film display and lighting technology of the future, but for lighting applications their diminishing efficiency at high brightness is a problem, the underlying cause of which is unclear. In a comprehensive analysis of phosphorescent OLEDs, the authors find, in contrast to previous conclusions, that in these devices triplet-polaron quenching (TPQ) is the dominant process behind the efficiency roll-off. This style of analysis and the understanding it brings could provide a breakthrough in solid-state lighting performance.

Memristors (resistors that track their history of current flow) have been proposed to improve the speed and density of logic and nonvolatile memory devices. In memristors based on titania, it is known that oxygen-deficient phases develop, creating an interface that is thought to be central to their behavior. The authors calculate the band alignment between TiO${}_2$ and Ti${}_4$O${}_7$ and conclude that channels of the latter can donate charge to the titania matrix, confirming the importance of these phases to device action.

Tomorrow’s much anticipated quantum computers, exotic as they may be, will require complex classical hardware for their control and operation. For solid-state quantum processors, the authors propose an efficient scheme for executing a quantum algorithm via a multicomponent classical interface. These components, which include cryogenic classical logic, are assembled to demonstrate control of a quantum-dot qubit. Thus, when the new wave of hardware finally arrives, we will be ready–and able–to use it.

Designers of next-generation photovoltaics look to employ abundant, environmentally benign materials, and currently zinc selenide is of interest. Unfortunately, the wide band gap of ZnS quantum dots (QDs) limits their application in solar cells. The authors show that introducing intermediate energy levels in these QDs via doping with manganese is effective in expanding their absorption window into the visible region, and thus improving device performance.

Small-angle x-ray scattering (SAXS) is widely used to study the nanoscale structure of catalysts, a key property that determines their activity in e.g. fuel cells, chemical reactors, and automotive catalytic converters. The authors reveal a strong SAXS interference effect, due to spatial correlations between catalyst nanoparticles and their supporting material, and provide a mathematical model to handle this interference in data analysis. These results help to overcome an important barrier to catalyst optimization.

Optimizing batteries is a major theme in energy research, for which better electrode materials are needed. Li${}_2$MnO${}_3$ has long been considered for lithium ion batteries, yet its intrinsic delithiation mechanism is not well understood, and its practical performance remains poor. In this study, defect calculations reveal that, unlike in the related LiMnO${}_2$, lithium release in Li${}_2$MnO${}_3$ involves oxidation at the oxygen site, not the manganese site, leading to bound oxygen-hole polarons. This insight into the unconventional mechanism indicates that nanostructuring and doping could yield high-capacity cathodes.

Keeping mesoscopic electronics cool is a significant challenge, for which carbon nanotubes (CNTs) are useful, in principle. However, so far there has been a discrepancy between experimental results and theoretical predictions of how CNTs transfer heat under bending deformation–an important issue in powering mobile devices with body heat, or cooling flexible electronics. Using objective molecular dynamics, the authors provide a comprehensive study of length- and curvature-dependent transport of phonons in bent CNTs, reconciling experiment and theory, with important implications for nanoscale thermal management and phononic devices.