Editor's Highlights - Communications Physics

Quantifying, controlling, and correcting noise related errors is one of the current challenges in quantum computing. Here, the authors study the time dependence of the relaxation of a stationary state simulated on a quantum computer, and show that such spectroscopic signature is unique and can be used to characterize the noise on individual quantum computers.

Cavity optomechanics studies interactions between mechanical oscillators and the radiation pressure induced by intracavity photons. The authors embedded a nonlinear Josephson junction in their microwave cavity to make the cavity response highly nonlinear and observed a counter-intuitive optomechanical process, blue-tone mechanical cooling.

Drainage and imbibition in porous media are two opposite fluid displacement scenarios with remarkably different underlying mechanisms. Here, the authors demonstrate that strong imbibition in porous media shows features of self-organized criticality previously observed only in drainage

The presence of geometric boundaries is known to affect the collective behaviour of active particles. Here, the authors unravel exotic patterns of self-propulsion and non-equilibrium shape fluctuations in a system of active particles enclosed in a droplet and interacting with its soft boundaries.

Auxetics are an unusual family of materials that, for instance, when stretched in a particular direction will exhibit an expansion of the dimensions that are perpendicular to the applied stress; however, despite many known examples of auxectics there is no universal description of the material properties. Here, the authors report a model based on antiferromagnetic spins and demonstrate how this can be used to design a auxetic material with a Poisson ratio of -1 over a range of finite strain.

The move to the quantum internet demands developments in communication networks that are based on quantum entanglement. The authors discuss the phenomenon of entanglement percolation in a quantum network presenting solutions to significantly accelerate the intensive computation effort involved in the process.

The authors study an interesting phenomena of shape coexistence in ¹⁸⁶Pb. In an elegant and well-documented experiment, they confirm the coexistence of the three 0⁺ states in the ¹⁸⁶Pb nucleus and reassign the shapes associated with the excited 0⁺ states.

Most bound quantum states in condensed matter systems emerge due to two-body interactions. Here, the formation of a stable three-particle bound state, induced by irreducible three-particle interactions in an antiferromagnetic spin ladder, is evidenced analytically and numerically for realistic material parameters.

The non-Hermitian skin effect comprises of boundary localised eigenmodes and has been realised in a range of 1D systems such as photonics and metamaterials. Here, the authors achieve the same effect in a quantum many-body setting using ultra-cold gases and, by tuning the strength of the spin orbit coupling, realise a non-trivial band topology.

X-ray phase-contrast tomography offers a highly sensitive 3D imaging approach to investigate different disease-relevant networks at levels ranging from single cell through to intact organ. The authors present a concomitant study of the evolution of tissue damage and inflammation in different organs affected by the disease in the murine model for multiple sclerosis.

The bulk-boundary correspondence is a defining feature of non-trivial topological matter and extends from the many topological orders that can exist in these systems. Here, the authors theoretically propose a feature distinct from the conventional bulk-boundary correspondence whereby localised modes exist between two flat-band systems with different geometric characters.

Interaction of active matter with geometrical and topological constraints is a topic of intense research in the recent few years due to its potential for design and control of active flow patterns. Here, the authors experimentally study the growth and expansion of cell aggregates interleaved by passive colloidal particles, showing that inert particles can reshape the collective pattern formation in cellular aggregates.

While 3D printing applications range from aerospace manufacturing to the design of drug delivery systems, current technologies reaching the micro and nanoscale resolution are limited by the complexity and cost of their components. Here, the authors show that nanoscale cost-effective 3D printing can be achieved by using a gaming console optical drive pickup for 3D photopolymerization.

Intermediate band solar cell is a type of photovoltaic cell which includes additional narrow band states which allow absorption of low energy below-bandgap photons that might otherwise be transmitted from the host material. Here, the authors report a type of ratchet intermediate band solar cell prepared by doping GaAs with erbium and investigate the underlying energy transfer mechanisms.

Characterizing the interactions between viral and human proteins is key to understand the function and structure of viruses such as SARS-CoV-2 and for informing drug design and repurposing strategies. Here, the authors use statistical physics techniques to perform a systematic multiscale comparison of the effects on the human interactome of SARS-CoV-2 with respect to other viruses, and find that COVID-19 exhibits properties typical of systemic diseases.

URu₂Si₂ is known to exhibit a lower temperature phase transition termed a ‘hidden order’ due to the difficulty its detection using conventional solid-state probes and the exact mechanism still remains unknown. Here, the authors use scanning tunnelling microscopy to reveal a 1D charge density wave for cleaved samples of URu₂Si₂ and demonstrate a potential connection with the hidden order state.

Atoms embedded in dense hot plasmas are affected by complex many-body interactions which challenges our capacity to model high energy density plasma. The authors propose a solution to the effects of many-body interactions on ions in dense plasmas, with a particular focus on the threebody interaction.

Implementing large-scale quantum networks is one of the challenges at the core of quantum communication. Here, the authors present NetSquid, a quantum network simulator that allows studying how such networks can be built, including physical hardware modelling, modularity, scalability, and examples.

Emerging experimental observation suggests that asymmetrical partitioning in cell division plays an important role in cell-to-cell variability, cell fate determination, cellular aging, and rejuvenation. Here, the authors propose a method based on multicolor flow cytometry to measure asymmetric division of cellular organelles, finding that cell cytoplasm is divided symmetrically but mitochondria and membrane lipids are asymmetrically distributed, and explain these observations through a minimal model of asymmetric partitioning based on biased binomial statistics.

The manipulation of spins with ultrafast lasers is a promising route to control the properties of a wide variety of quantum materials. Here, the authors present a simulation of Floquet-engineered spin fluctuations in a correlated system and of their fingerprints in ultrafast inelastic X-ray scattering experiments.

The gain and loss inherent in non-Hermitian quantum systems can modify the flow of coherence between subsystems, which may be lost or recovered from the environment. Here, the coherence flow in PT-symmetric and anti-PT symmetric systems is investigated experimentally and theoretically.

Mechanical forces play important roles in cell biology and traction force microscopy (TFM) experiments have enabled quantification of the cell-generated forces when placed on substrates of distinct stiffnesses. Here the authors evaluate the effect of the Poisson’s ratio- one of the main descriptors of the material’s mechanical behaviour together with the Elastic Modulus, in the context of TFM experiments.

Liquid scintillator detectors have been used to study neutrinos ever since their discovery in 1956. The authors introduce an opaque scintillator detector concept for future neutrino experiments with increased capacity for particle identification and a natural affinity for doping.

Graphene-based Josephson junctions can make highly sensitive quantum probes and are dependent on properties related to the current phase relationship. Here, the authors theoretically investigate the power spectrum of the critical current fluctuations in graphene Josephson junctions and demonstrate that they have a 1/f dependence on frequency.

Water expands upon freezing, so what happens when it is brought below 0 °C in an undeformable, constant-volume container? Here, the authors use classical thermodynamics and kinetics to derive the phenomenology of freezing in an isochoric chamber, developing a framework therefrom to study the origin of the limiting effects of confinement on ice formation.

Established to explain high-energy particle physics, supersymmetry has since been invoked to describe the interplay between symmetry and topology in numerous fields. Here, supersymmetric transformations are shown theoretically and experimentally to destroy and restore topology in a photonic crystal.

Swarming is a ubiquitous behaviour in living systems, emerging from local interactions. Here, the authors exploit genetic mutations to experimentally characterize how distinct swarming phases of Bacillus subtilis emerge as a function of the shape and density of these bacteria.

Bound states in the continuum have recently found application to sensing, lasing and optoelectronics, but have not been realised in 1D. Here, destructive interference of electron spin in a tilted magnetic field is shown to give rise to bound states in the continuum of a 1D layered photonic crystal.

The assembly and manipulation of synthetic microswimmers often exploits parallels with living systems. Here, the authors show precessing magnetic fields induce rotation and translation in large self-assembled rafts of magnetic beads thanks to metachronal waves and in analogy with ciliates swimmers

How friction in liquids emerges from conservative forces between atoms is currently not well-understood, but it is a crucial parameter for dynamic processes in liquid matter. Here, the authors combine frequency-resolved simulation data with theory to show that the friction felt by a single molecule occurs abruptly below a certain frequency.

Floquet engineering describes the control of a quantum system using light-matter interactions and has received renewed interest due to recent developments in ultrafast spectroscopy techniques. Here, the authors use light scattering spectroscopy to investigate the Floquet state in MoS₂ and apply dynamical symmetries to understand the polarisation selection rules

Can living systems function as artificial neural networks for biophysical applications? Here, the authors show that living tumor spheroids can be employed as random optical learning machines and used to investigate cancer morphodynamics and quantify the effect of chemotherapy.

Control of nonlinear optical processes at the nanoscale is vital for the generation of on-chip short-wavelength sources, yet strong re-absorption of this radiation limits its efficiency in solids. Here, high harmonics are generated in an array of 1D silicon ridge waveguides, mitigating bulk re-absorption.

Large-scale containment measures that reduce the spread of COVID-19 have proven to have too large an impact on both the economy and our mental health to be sustainable in the long term. Here, the authors show that travel reductions between geographical regions and timely local control measures can reduce the region-to-region reproduction number below one, thus eliminating the epidemic and preventing recurrent waves without the need for long-term lockdown measures.

The chiral spin texture hosted by Kagome lattices is emerging as a prominent playground for investigating exotic phenomena related to topological quantum phases. Here the authors utilize a tight-binding approach to unveil the existence of spontaneous interactions capable of bridging the gap between magnonics and spin-orbitronics.

Quantum communication and computing is now in a data-intensive domain where a classical network describing a quantum system seems no longer sufficient to yield a generalization of complex networks methods to the quantum domain. The authors review recent progress into this paradigm shift that drives the creation of a network theory based fundamentally on quantum effects.

Magnonics involves the manipulation of spin waves in order to develop more energy efficient spintronics devices which do not rely on the movement of electronic charge. Here, the authors review the various methods designed to control magnonics with particular focus on voltage i.e. electric-field.

Optical frequency combs were realized nearly two decades ago to support the development of the world’s most precise atomic clocks, but their versatility has since made them useful instruments well beyond their original goal, and spans across a wide variety of fundamental and applied physics in a wide range of wavelengths. Fortier and Baumann present a comprehensive review of developments in optical frequency comb technology and a view to the future with these technologies.

The concept of non-Hermitian parity-time reversal symmetry in optics has given rise to a vast amount of research aimed at exploring some of the exotic features displayed by photonics systems. The authors present a brief account of the state-of-the-art on non-Hermitian photonics and provide their perspective on the topic.

The anapole, a non-radiating charge-current configuration, was recently observed in a variety of artificial materials and nanostructures. We provide a brief overview of this rapidly developing field and discuss implications for spectroscopy, energy materials, electromagnetics, as well as quantum and nonlinear optics.

The successful isolation of a single layer of graphene has led to great interest in finding other 2D materials with similar electronic characteristics with additional spin-dependent phenomena. In this work, a 2D allotrope of Sn is grown on an Au(111) surface and shown through angle-resolved photoemission spectroscopy to have a linear band dispersion at the zone center and anti-parallel spin polarization.

The valley Hall effect in transition metal dichalcogenides has been studied as a potential mean to develop new electronic and optoelectronic devices. The authors theoretically demonstrate that valley Hall effect can be derived from spin degrees of freedom, which is distinct from the conventional orbital related type.

Semiconductor microcavities coupled to a quantum well can produce three regimes of coherent light generation depending on the nature of the light–matter and electron–hole interactions. The authors design a Se/Te based microcavity containing a single quantum well which enables them to achieve all three lasing regimes in the one device.

The aim of quantum communications is to transmit quantum information at high rate over long distances, something that can only be achieved by quantum repeaters and quantum networks. Here the author presents the ultimate end-to-end capacities of a quantum network, also showing the advantages of multipath network routing versus single repeater chains.

BaFe₂Se₃ is a ladder-compound that exhibits superconductivity under pressure. Using a density matrix renormalization group calculation to compare results with resonant inelastic X-ray scattering measurements, the authors conclude that this material is realized in an orbital-selective Mott phase.

Revealing how to effectively produce nuclei remains one of the main motivations of recent nuclear reaction and nuclear transmutation studies of radioactive waste. The authors show the enhancement of proton rich isotope production using incomplete fusion mechanism on weakly bound nuclei using the incomplete fusion mechanism by the inverse kinematics technique, in which a radioactive beam of Palladium bombards a proton/deuteron target.

Prospects for new applications in quantum simulations, spectroscopic precision measurements and very low temperature physics and chemistry have resulted in significant advances in the study of cold molecules, with their trapping for long times remaining a major challenge. The authors present an experiment in which polar molecular radicals produced by Stark deceleration are magnetically trapped for a time of order 20 s providing an improvement of up to two orders of magnitude over room temperature experiments.

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.

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.

Small-world networks describe mathematically many natural and man-made networks such as neurons, power grids or social networks, but a measure of how small a small-world network is, remains a subject of debate. The authors identify the limiting cases with the shortest and longest average path for a given number of nodes and edges, which can be used as benchmarks to evaluate the average shortest path length for both empirical and model networks.

Progress in quantum technologies calls for increased precision in probing quantum systems. The authors present a method for substantially improving the precision bound of ultra low-temperature thermometry via dynamical control of a quantum thermometer.