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Nonlocal metasurfaces are currently emerging as advanced tools for the manipulation of electromagnetic radiation, going beyond the widely explored Huygens metasurface concept. Nonetheless, the lack of an unified approach for their fast and efficient tunability still represents a serious challenge to overcome. This study reports on the gigahertz modulation of a dielectric slab‐based, nonlocal (i.e., angle‐dispersive) metasurface, whose operation relies on the optomechanical coupling with a mechanical wave excited piezoelectrically by a transducer integrated on the same chip. Importantly, the metasurface region is free from any conductive material, thus eliminating optical losses, and making the device of potential interest for delicate environments such as high‐power apparatuses or quantum optical systems. [ABSTRACT FROM AUTHOR]

We evaluated GaAs nanoparticle-concentrations in the air and on skin and surfaces in a research facility that produces thin films, and to monitored As in the urine of exposed worker. The survey was over a working week using a multi-level approach. Airborne personal monitoring was implemented using a miniature diffusion size classifier (DiSCMini) and IOM sampler. Environmental monitoring was conducted using the SKC Sioutas Cascade Impactor to evaluate dimensions and nature of particles collected. Surfaces contamination were assessed analyzing As and Ga in ghost wipes. Skin contamination was monitored using tape strips. As and Ga were analyzed in urines collected every day at the beginning and end of the shift. The greatest airborne exposure occurred during the cutting operations of the GaAs Sample (88883 np/cm3). The highest levels of contamination were found inside the hood (As max = 1418 ng/cm2) and on the laboratory floor (As max = 251 ng/cm2). The average concentration on the worker's skin at the end of the work shift (3.36 ng/cm2) was more than 14 times higher than before the start of the shift. In weekly urinary biomonitoring an average As concentration of 19.5 µg/L, which was above the Società Italiana Valori di Riferimento (SIVR) reference limit for the non-occupational population (2.0 – 15 µg/L), but below the ACGIH limit (30 µg/L). Overall, airborne monitoring, surface sampling, skin sampling, and biomonitoring of worker confirmed the exposure to As of workers. Systematic cleaning operations, hood implementation and correct PPE management are needed to improve worker protection. [ABSTRACT FROM AUTHOR]

Understanding and control of thermal transport in solids at the nanoscale are crucial in engineering and enhance the properties of a new generation of optoelectronic, thermoelectric and photonic devices. In this regard, semiconductor superlattice structures provide a unique platform to study phenomena associated with phonon propagations in solids such as heat conduction. Transient X‐ray diffraction can directly probe atomic motions and therefore is among the rare techniques sensitive to phonon dynamics in condensed matter. Here, optically induced transient heat conduction in GaAs/AlAs superlattice structures is studied using the EIGER2 detector. Benchmark experiments have been performed at the Austrian SAXS beamline at Elettra–Sincrotrone Trieste operated in the hybrid filling mode. This work demonstrates that drifts of experimental conditions, such as synchrotron beam fluctuations, become less essential when utilizing the EIGER2 double‐gating mode which results in a faster acquisition of high‐quality data and facilitates data analysis and data interpretation. [ABSTRACT FROM AUTHOR]

In this work, we experimentally analyze the periodic oscillations that take place in staircase APDs with separate absorption and multiplication regions when operating under continuous laser light. These oscillations increase in frequency when the APD gain increases. We have verified that they are not affected by the parameters (gain and bandwidth) of the transimpedance amplifier, and thus originate inside the APD. The phenomenon is analyzed systematically by considering devices with different thicknesses of the absorption region. Possible physical interpretations related to the flux of holes generated by impact ionization are provided. [ABSTRACT FROM AUTHOR]

We demonstrate that absorption saturation of a mid-infrared intersubband transition can be engineered to occur at moderate light intensities of the order of 10–20 kW cm−2 and at room temperature. The structure consists of an array of metal–semiconductor–metal patches hosting a judiciously designed 253 nm thick GaAs/AlGaAs semiconductor heterostructure. At low incident intensity, the structure operates in the strong light–matter coupling regime and exhibits two absorption peaks at wavelengths close to 8.9 μm. Saturation appears as a transition to the weak coupling regime—and therefore, to a single-peaked absorption—when increasing the incident intensity. Comparison with a coupled mode theory model explains the data and permits to infer the relevant system parameters. When the pump laser is tuned at the cavity frequency, the reflectivity decreases with increasing incident intensity. When instead the laser is tuned at the polariton frequencies, the reflectivity non-linearly increases with increasing incident intensity. At those wavelengths, the system, therefore, mimics the behavior of a saturable absorption mirror in the mid-IR range, a technology that is currently missing. [ABSTRACT FROM AUTHOR]

Wave refraction at an interface between different materials is a basic yet fundamental phenomenon, transversal to several scientific realms – electromagnetism, gas and fluid acoustics, solid mechanics, and possibly also matter waves. Under specific circumstances, mostly enabled by structuration below the wavelength scale, i.e., through the metamaterial approach, waves undergo negative refraction, eventually enabling superlensing and transformation optics. However, presently known negative refraction systems are symmetric, in that they cannot distinguish between positive and negative angles of incidence. Exploiting a metamaterial with an asymmetric unit cell, we demonstrate that the aforementioned symmetry can be broken, ultimately relying on the specific shape of the Bloch mode isofrequency curves. Our study specialized upon a mechanical metamaterial operating at GHz frequency, which is by itself a building block for advanced technologies such as chip-scale hybrid optomechanical and electromechanical devices. However, the phenomenon is based on general wave theory concepts, and it applies to any frequency and time scale for any kind of linear waves, provided that a suitable shaping of the isofrequency contours is implemented. Known examples of negative refraction in metamaterials do not distinguish between positive and negative angles of incidence. Here, the authors show that it is possible to break this symmetry using an asymmetric unit cell, and demonstrate it using a mechanical metamaterial working at GHz frequencies. [ABSTRACT FROM AUTHOR]

In hard X-ray applications that require high detection efficiency and short response times, such as synchrotron radiation-based Mössbauer absorption spectroscopy and time-resolved fluorescence or photon beam position monitoring, III–V-compound semiconductors, and dedicated alloys offer some advantages over the Si-based technologies traditionally used in solid-state photodetectors. Amongst them, gallium arsenide (GaAs) is one of the most valuable materials thanks to its unique characteristics. At the same time, implementing charge-multiplication mechanisms within the sensor may become of critical importance in cases where the photogenerated signal needs an intrinsic amplification before being acquired by the front-end electronics, such as in the case of a very weak photon flux or when single-photon detection is required. Some GaAs-based avalanche photodiodes (APDs) were grown by a molecular beam epitaxy to fulfill these needs; by means of band gap engineering, we realised devices with separate absorption and multiplication region(s) (SAM), the latter featuring a so-called staircase structure to reduce the multiplication noise. This work reports on the experimental characterisations of gain, noise, and charge collection efficiencies of three series of GaAs APDs featuring different thicknesses of the absorption regions. These devices have been developed to investigate the role of such thicknesses and the presence of traps or defects at the metal–semiconductor interfaces responsible for charge loss, in order to lay the groundwork for the future development of very thick GaAs devices (thicker than 100 μ m) for hard X-rays. Several measurements were carried out on such devices with both lasers and synchrotron light sources, inducing photon absorption with X-ray microbeams at variable and controlled depths. In this way, we verified both the role of the thickness of the absorption region in the collection efficiency and the possibility of using the APDs without reaching the punch-through voltage, thus preventing the noise induced by charge multiplication in the absorption region. These devices, with thicknesses suitable for soft X-ray detection, have also shown good characteristics in terms of internal amplification and reduction of multiplication noise, in line with numerical simulations. [ABSTRACT FROM AUTHOR]

Public transport use has drastically declined during the COVID-19 pandemic because the virus spreads through close contact with infected people and contaminated surfaces, especially in closed-environments. Evidence suggests that following the necessary safety guidelines can limit the spread of the virus, however, non-compliance to precautionary measures has been reported widely. Ignoring the precautionary measures may lead to quick transmission of the virus since public transport vehicles generally resemble closed-environments. This study explores people's intentions to use public transport during the COVID-19 pandemic while adhering to precautionary measures. For this purpose, a total of 1516 useable responses were collected through a questionnaire survey conducted in Lahore, Pakistan. Regression models were developed to model the intentions to use public transport during the pandemic, to adhere to the precautionary measures while using public transport during the pandemic, and to use public transport while suffering from COVID-19 disease. The results of this study will help in understanding the intentions of the public transport users during the COVID-19 pandemic. It will also provide insights for policymakers and public transport operators about further necessary actions to promote safe public transport use during the current and any possible future pandemics. As public transport use declined during the pandemic, policy implications for alternative mobility options such as demand-responsive-transport (DRT) are also presented. Considering the study results, a policy interventions framework is proposed to promote the safe use of various public transport modes, particularly in developing regions. [ABSTRACT FROM AUTHOR]

Applications relying on mid-infrared radiation (λ ~ 3-30 μm) have progressed at a very rapid pace in recent years, stimulated by scientific and technological breakthroughs like mid-infrared cameras and quantum cascade lasers. On the other side, standalone and broadband devices allowing control of the beam amplitude and/or phase at ultra-fast rates (GHz or more) are still missing. Here we show a free-space amplitude modulator for mid-infrared radiation (λ ~ 10 μm) that can operate at room temperature up to at least 1.5 GHz (−3dB cutoff at ~750 MHz). The device relies on a semiconductor heterostructure enclosed in a judiciously designed metal–metal optical resonator. At zero bias, it operates in the strong light-matter coupling regime up to 300 K. By applying an appropriate bias, the device transitions towards the weak-coupling regime. The large change in reflectance is exploited to modulate the intensity of a mid-infrared continuous-wave laser up to 1.5 GHz. Broadband integrated electrical modulators are key components for photonic systems. Here, the authors present a room temperature mid-IR free-space amplitude modulator based on a semiconductor heterostructure that exploits the change in reflectance occurring at the change between weak and strong coupling. [ABSTRACT FROM AUTHOR]

The coupling between electromagnetic fields and mechanical motion in micro‐ and nanostructured materials has recently produced intriguing fundamental physics, such as the observation of mesoscopic optomechanical phenomena in objects operating in the quantum regime. It is also yielding innovative device applications, for instance in the manipulation of the optical response of photonic elements. Following this concept, here it is shown that combining a nanostructured chiral metasurface with a semiconductor suspended micromembrane can open new scenarios where the mechanical motion affects the polarization state of a light beam, and vice versa. Optical characterization of the fabricated samples, assisted by theory and numerical modeling, reveals that the interaction is mediated via moving‐boundary and thermoelastic effects, triggered by intracavity photons. This work represents a first example of "Polarization Optomechanics," which can give access to new forms of polarization nonlinearities and control. It can also lead to wide applications in fast polarimetric devices, polarization modulators, and dynamically tunable chiral state generators and detectors. [ABSTRACT FROM AUTHOR]

A new setup for picosecond pump–probe X‐ray scattering at the Austrian SAXS beamline at Elettra‐Sincrotrone Trieste is presented. A high‐power/high‐repetion‐rate laser has been installed on‐site, delivering UV/VIS/IR femtosecond‐pulses in‐sync with the storage ring. Data acquisition is achieved by gating a multi‐panel detector, capable of discriminating the single X‐ray pulse in the dark‐gap of the Elettra hybrid filling mode. Specific aspects of laser‐ and detection‐synchronization, on‐line beam steering as well protocols for spatial and temporal overlap of laser and X‐ray beam are also described. The capabilities of the setup are demonstrated by studying transient heat‐transfer in an In/Al/GaAs superlattice structure and results are confirmed by theoretical calculations. [ABSTRACT FROM AUTHOR]

Photonic band structures are a typical fingerprint of periodic optical structures, and are usually observed in spectroscopic quantities such as transmission, reflection, and absorption. Here we show that the chiro-optical response of a metasurface constituted by a lattice of non-centrosymmetric, L-shaped holes in a dielectric slab shows a band structure, where intrinsic and extrinsic chirality effects are clearly recognized and connected to localized and delocalized resonances. Superchiral near-fields can be excited in correspondence to these resonances, and anomalous behaviors as a function of the incidence polarization occur. Moreover, we have introduced a singular value decomposition (SVD) approach to show that the above mentioned effects are connected to specific fingerprints of the SVD spectra. Finally, by means of an inverse design technique we have demonstrated that the metasurface based on an L-shaped hole array is a minimal one. Indeed, its unit cell geometry depends on the smallest number of parameters needed to implement arbitrary transmission matrices compliant with the general symmetries for 2d-chiral structures. These observations enable more powerful wave operations in a lossless photonic environment. [ABSTRACT FROM AUTHOR]

We report quantum well mid-infrared photo-detectors operating in the strong light-matter coupling regime. We claim that this is an ideal system to elucidate the elusive problem in intersubband polaritonics of the injection of electrons (single-particle fermionic states) into polaritonic modes (bosonic excitations). By reversing the perspective and focusing on the electron extraction, we have obtained experimental information on the transfer function between a polaritonic system and an electronic reservoir. In addition to its interest for fundamental science, this approach also opens promising avenues in view of adding previously unavailable functionalities to quantum well detectors and improving their performance. [ABSTRACT FROM AUTHOR]

We report on the effects of optical disorder on breaking the symmetry of the cavity modes of H3 photonic crystal cavities incorporating site-controlled pyramidal quantum dots (QDs) as the internal light source. The high in-plane symmetry of the polarization states of the pyramidal QDs simplifies the analysis of the polarization states of the H3 cavities. It is shown that the optical disorder induced by fabrication imperfections lifts the degeneracy of the two quadrupole cavity modes and tilts the elongation axes of the cavity mode patterns with respect to the ideal, hexagonal symmetry case. These results are useful for designing QD-cavity structures for polarization-entangled photon sources and few-QD lasers. [ABSTRACT FROM AUTHOR]

We report on the effects of optical disorder on breaking the symmetry of the cavity modes of H3 photonic crystal cavities incorporating site-controlled pyramidal quantum dots (QDs) as the internal light source. The high in-plane symmetry of the polarization states of the pyramidal QDs simplifies the analysis of the polarization states of the H3 cavities. It is shown that the optical disorder induced by fabrication imperfections lifts the degeneracy of the two quadrupole cavity modes and tilts the elongation axes of the cavity mode patterns with respect to the ideal, hexagonal symmetry case. These results are useful for designing QD-cavity structures for polarization-entangled photon sources and few-QD lasers. [ABSTRACT FROM AUTHOR]

The origin of the anomalous transport feature appearing at a conductance G ≈ 0.7 × (2e/h) in quasi-1D ballistic devices-the so-called 0.7 anomaly-represents a long standing puzzle. Several mechanisms have been proposed to explain it, but a general consensus has not been achieved. Proposed explanations have been based on quantum interference, the Kondo effect, Wigner crystallization, and other phenomena. A key open issue is whether the point defects that can occur in these low-dimensional devices are the physical cause behind this conductance anomaly. Here we adopt a scanning gate microscopy technique to map individual impurity positions in several quasi-1D constrictions and correlate these with conductance characteristics. Our data demonstrate that the 0.7 anomaly can be observed irrespective of the presence of localized defects, and we conclude that the 0.7 anomaly is a fundamental property of low-dimensional systems. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The ability to drive a system with an external input is a fundamental aspect of light-matter interaction. The key concept in many photonic applications is the 'critical coupling' condition: at criticality, all the energy fed to the system is dissipated within the system itself. Although this idea was crucial to enhance the efficiency of many devices, it was never considered in the context of systems operating in a non-perturbative regime. In this so-called strong-coupling regime, the matter and light degrees of freedom are mixed into dressed states, leading to new eigenstates called polaritons. Here we demonstrate that the strong-coupling regime and the critical coupling condition can coexist; in such a strong critical coupling situation, all the incoming energy is converted into polaritons. A general semiclassical theory reveals that such a situation corresponds to a special curve in the phase diagram of the coupled light-matter oscillators. In the case of a system with two radiating ports, the phenomenology shown is that of coherent perfect absorption (CPA; refs , ), which is then naturally understood in the framework of critical coupling. Most importantly, we experimentally verify polaritonic CPA in a semiconductor-based intersubband-polariton photonic crystal resonator. This result opens new avenues in polariton physics, making it possible to control the pumping efficiency of a system independent of the energy exchange rate between the electromagnetic field and the material transition. [ABSTRACT FROM AUTHOR]

We demonstrate mid-infrared detectors embedded into an array of double-metal nano-antennas. The antennas act as microcavities that squeeze the electric field into thin semiconductor layers, thus enhancing the detector responsivity. Furthermore, thanks to the ability of the antennas to gather photons from an area larger than the device's physical dimensions, the dark current is reduced without hindering the photo-generation rate. In these devices, the background-limited performance is improved with a consequent increase of the operating temperature. Our results illustrate how the antenna-coupled microcavity concept can be applied to enhance the performances of infrared opto-electronic devices. [ABSTRACT FROM AUTHOR]

We demonstrate that the formation of GaAs quantum wires on self-limiting AlGaAs grown on V grooves occurs via a transient increase of the growth rates in a set of different nanofacets. Upon growth of sufficiently thick layers on AlGaAs, the GaAs surface reaches a self-limiting profile as well, through an equalization of the relative growth rates on these facets. Atomic force microscopy studies show that the step density in the facets along the groove evolves with GaAs thickness in the same way as the facets extension, thus suggesting a role of the step distribution in the establishment of the self-limiting profiles. The self-limiting GaAs groove profile is much broader than the AlGaAs one at corresponding growth temperatures; however, it can be sharpened down to a radius of curvature of 5 nm for T = 550°C. Under these conditions, GaAs was successfully used as a barrier material for growing vertical arrays of self-ordered InGaAs wires. [ABSTRACT FROM AUTHOR]

Bismuth oxychloride photocatalysts were obtained using solvothermal synthesis and different additives (CTAB—cetyltrimethylammonium bromide, CTAC—cetyltrimethylammonium chloride, PVP–polyvinylpyrrolidone, SDS–sodium dodecylsulphate, U—urea and TU—thiourea). The effect of the previously mentioned compounds was analyzed applying structural (primary crystallite size, crystal phase composition, etc.), morphological (particle geometry), optical (band gap energy) parameters, surface related properties (surface atoms' oxidation states), and the resulted photocatalytic activity. A strong dependency was found between the surface tension of the synthesis solutions and the overall morpho-structural parameters. The main finding was that the characteristics of the semiconductors can be tuned by modifying the surface tension of the synthesis mixture. It was observed after the photocatalytic degradation, that the white semiconductor turned to grey. Furthermore, we attempted to explain the gray color of BiOCl catalysts after the photocatalytic decompositions by Raman and XPS studies. [ABSTRACT FROM AUTHOR]

In various fields such as the 5G antenna system and satellite communication system, there is a growing demand to develop a smart antenna with a frequency selective or beamforming function within a limited space. While antennas utilizing mechanical, electronic, and material characteristics are being studied, a method of having tunable frequency characteristics by applying a liquid crystal material with dielectric anisotropy to a planar patch antenna is proposed. In resonance mode, the design method for using only the minimum amount of expensive liquid crystals is systematically arranged while maximizing the amount of change in the operating frequency of the antenna by considering the electric field distribution on the surface of the patch antenna. Furthermore, to increase the dielectric anisotropy of the liquid crystal, the liquid crystal must be aligned. Simultaneously, in cases where the cell gap of the liquid crystal exceeds 100 μm, the alignment force is weakened. While compensating for this shortcoming, securing the radiation characteristics of the antenna is proposed, and simulations are performed. [ABSTRACT FROM AUTHOR]

In this work we demonstrate the achievement of light-matter strong coupling regime between an intersubband transition and the photonic bandlike mode supported by a metallic grating. Polaritonic resonances have been identified in the reflectivity spectra at 10° incidence, with a clear anticrossing appearing when the photonic mode is tuned across the transition line. Experimental results are in good agreement with the simulations performed with a scattering-matrix approach. This cavity design can be further optimized and is likely to open the way to a new class of time-resolved measurements, as it allows pump-and-probe measurements to be performed in collinear geometries. [ABSTRACT FROM AUTHOR]

A surface-acoustic-wave (SAW) driven light-emitting-diode structure that can implement a single-photon source for quantum-cryptography applications is demonstrated. Our lateral n-i-p junction is realized starting from an undoped GaAs/AlGaAs quantum well by gating. It incorporates interdigitated transducers for SAW generation and lateral gates for current control. We demonstrate acoustoelectric transport and SAW-driven electroluminescence. The acoustoelectric current can be controlled down to complete pinch-off by means of the lateral gates. [ABSTRACT FROM AUTHOR]

The properties of self-assembled InAs/GaAs quantum rings are investigated by conductive atomic force microscopy. Our two-dimensional current maps and current-voltage curves show a lower conductivity of the central ring hole as compared to rim and surrounding planar region. This result is quite surprising if we take into account the compositional profile of quantum rings: being the region with the highest In concentration, one would expect the central hole to be the region with the highest conductivity. However, including the presence of a surface oxide into numerical simulations yields consistent results, which show the same qualitative behavior as the measured conductivities. [ABSTRACT FROM AUTHOR]

We report on the coupling of optical transitions between excited conduction subbands in GaAs/AlGaAs heterostructures with the resonant photonic mode of a semiconductor microcavity. The coupling is found to increase with temperature, owing to the thermal excitation of carriers from the ground subband and, thanks to the large dipole-matrix element of the excited-state transition, a record splitting of 60 meV is shown in the room-temperature reflectance. The importance of translating the angle-dependent spectra into energy-wavevector dispersion when the coupling is so large is highlighted, and a theoretical fitting procedure is used to extract the value of the vacuum-field Rabi energy. [ABSTRACT FROM AUTHOR]

The authors report the external control of the polariton ground state by manipulating the coupling between the intersubband transition and the photonic mode of a GaAs/AlGaAs microcavity. The vacuum-field Rabi splitting is varied by means of charge transfer between the energetically-aligned ground subbands of asymmetric tunnel-coupled quantum wells. The authors propose the use of this structure concept for implementing ultrafast modulation of intersubband polaritons. [ABSTRACT FROM AUTHOR]

We demonstrate the external control of the coupling between the intersubband transition and the photonic mode of a GaAs/AlGaAs microcavity with multiple quantum wells embedded. By electrical gating, the charge density in the wells can be lowered, thereby quenching the intersubband polaritons and reverting the system to uncoupled excitations. The angle-dependent reflectance measurements are in good agreement with theoretical calculations performed in the transfer matrix formalism. The experiment shows the prospects offered by intersubband microcavities through manipulation of the system ground state. [ABSTRACT FROM AUTHOR]

We demonstrate selective electrodeposition of magnetic layers on doped semiconductors resulting in a self-aligned pattern which replicates the doping pattern in the semiconductor surface. A Schottky barrier forms at the interface between a semiconductor substrate and the electrolyte, which upon application of a cathodic potential is biased in the forward (reverse) direction for n- or p-type semiconductors, respectively. Electron transfer from an n-type semiconductor is thus possible, while breakdown of the Schottky barrier would be necessary for deposition on a p-type substrate. The process will thus be spatially selective on a lateral modulation of the substrate doping. As an example we demonstrate the deposition of Co on GaAs. [ABSTRACT FROM AUTHOR]

We report on the systematic study of two main scattering mechanisms on intersubband transitions, namely ionized impurity scattering and interface roughness scattering. The former mechanism has been investigated as a function of the dopants position within a multiple GaAs/AlGaAs quantum well structure and compared to the transition of an undoped sample. The study on the latter scattering mechanism has been conducted using the growth interruption technique. We report an improvement of the intersubband (ISB) transition linewidth up to 11% by interrupting growth at GaAs-on-AlGaAs interfaces. As a result, the lifetime of intersubband polaritons could be improved up to 9%. This leads to a reduction of 17% of the theoretical threshold intensity for polaritonic coherent emission. This work brings a useful contribution towards the realization of polariton-based devices. [ABSTRACT FROM AUTHOR]

Hybrid superconductor/semiconductor devices constitute a powerful platform where intriguing topological properties can be investigated. Here, we present fabrication methods and analysis of Josephson junctions formed by a high‐mobility InAs quantum‐well bridging two Nb superconducting contacts. We demonstrate supercurrent flow with transport measurements, critical temperature of 8.1 K, and critical fields of the order of 3 T. Modulation of supercurrent amplitude can be achieved by acting on two side gates lithographed close to the two‐dimensional electron gas. Low‐temperature measurements reveal also well‐developed quantum Hall plateaus, showing clean quantization of Hall conductance. Here, the side gates can be used to manipulate channel width and electron carrier density in the device. These findings demonstrate the potential of these hybrid devices to investigate the coexistence of superconductivity and Quantum Hall effect and constitute the first step in the development of new device architectures hosting topological states of matter. Quantum Hall states in proximity to a superconductor are expected to host topologically protected quasiparticles with non‐trivial braiding properties, with potential applications in quantum technologies. As a first step toward this goal, here, Guiducci et al. demonstrate observation of the quantum Hall effect in a Josephson junction device based on an InAs quantum well. [ABSTRACT FROM AUTHOR]