Five Years of Communications Physics

Communications Physics is five years old. So we are celebrating, with a special anniversary collection. And as we do every day with exciting physics papers, we take a moment to reflect on our journey so far and our future direction.

February 22, 2023 marks an important milestone. We celebrate the fifth anniversary of Communications Physics.

For most lasing and photonic applications, it is essential to control the number of lasing modes that are present. In this work, an interface between two topologically distinct photonic crystals is used to ensure single-mode lasing with enhanced light-matter interactions due to a near-diffraction-limited mode volume.

Two-dimensional inorganic–organic hybrid perovskites are expected to play an important role in photovoltaic devices but suffer from issues related to dielectric confinement. The authors theoretically outline a method and experimentally succeed to overcome this issue by using materials with large dielectric constants.

Characterizing the non-equilibrium phase transition to a Bose-Einstein condensate is an open problem in condensed matter physics. The authors perform a detailed numerical characterization of this dynamical process, providing insights into the equilibration process after crossing the transition.

Observing the dynamical Casimir effect, where two particles are generated from the vacuum, is challenging in the optical regime due to its purely-temporal nature. The authors demonstrate a dispersion-oscillating fibre system operating in the near-infrared regime and capable of resolving correlated photon pairs as an analogue to the dynamical Casimir effect.

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.

Many real-world networks present structural symmetries that, while typically increasing robustness, deeply influence structural and dynamical properties. Here, the author studies the effect of symmetries on network measures and how they can be exploited to increase computational efficiency.

The discovery of superconductivity in doped NdNiO₂ has generated excitement due to similarities with cuprates. Here, the authors use first-principles calculations to show that different from cuprates, a hybridization between Ni d-orbitals and itinerant electrons in NdNiO₂ disfavours magnetism by screening Ni moment, as in Kondo systems.

Despite rapid scientific and technological development of organic polariton systems, the understanding of their nonlinear phenomena has eluded the community. This study unravels the mechanisms of the omnipresent energy shifts in organic polariton condensates, underlining the nonlinear dynamics in such systems.

How galaxies form their stars has been extensively studied but the role of the galactic gas content and the efficiency of its conversion into stars remain to be fully understood. Here the author presents a data-driven statistical analysis that reduces potential biases related to non-detections to quantify the link between star formation, molecular, and neutral gas in nearby galaxies.

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.

Manipulation of the magnetization is of major importance in spintronics. The authors demonstrate that an electric field triggers a transverse flow of orbital moment: the so-called orbital Hall effect. This enables the efficient magnetization control, holding the promise for fast and miniaturized memories and sensors.

Controlling active matter represents an exciting avenue for studying collective pattern formation. In this article the authors present optical control of persistent flows of active filaments-motor protein mixtures and show how boundaries determine the architecture of active flows

Flat bands in twisted transition metal dichalcogenide semiconductors can host a wide array of strongly correlated states of matter. Here, the authors theoretically identify a rich phase diagram of charge-ordered states with exotic magnetic ordering emerging in a new class of honeycomb Moiré superlattices.

Magnetic susceptibility measurements are an integral technique used across chemistry, physics and materials science; however, while straightforward to perform, interpretation of the data is often not. Here, the authors provide a basic guide to help newcomers interpret magnetic susceptibility data outlining examples based around the Curie-Weiss law that are ideal for those wishing to learn the basics of this method.

Experiments have shown that coupling ensembles of molecules to a cavity mode can modify chemical reactions, though theoretical studies have struggled to model the complexity of this many-body system. Here, matrix product states are used to study the reaction-relevant many-body quantum dynamics, revealing the importance of disorder on entanglement build-up.

Quantum fluctuations stabilize dense self-bound macroscopic quantum states in quantum gases. This work places an Erbium dipolar ultracold atomic gas with dominantly attractive long-range interactions in a 1D periodic lattice, and uses interferometric techniques and numerical modeling to characterize the importance of beyond mean-field effects, revealing the emergence of spatially-extended and single-site localized (2D) droplets and signatures of an anisotropic 2D soliton.

The discovery of topological insulators has given rise to a flourishing field dedicated to the investigation of the topological state of matter. This manuscript contributes to this field by introducing the idea of a topoelectrical circuit, whereby an assembly of conventional circuit elements realises various topological band structures.

For both fundamental and applied sciences topological states of matter is an area of intense research and most investigations are dedicated to realizing these materials using electronic and optical methods. Here the authors review recent efforts in a third avenue of research which seeks to emulate topological states using acoustics.

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 origin of Dark Matter (DM) in the Universe remains one of the main unresolved questions in Cosmology. The authors propose to probe a scenario where DM forms a compact object known as boson star, or a small DM halo bound to the Earth or sun, with a density higher than the local DM density making them detectable via atomic physics table top experiments.

Two dimensional materials can exhibit unique optical properties, making them interesting for new photonic devices and laser sources. Here, the strong optical nonlinearity of AuTe₂Se_4/3 is exploited to achieve a femtosecond infra-red laser with high stability.

The COVID-19 pandemic has demonstrated the need for non-pharmaceutical epidemic mitigation strategies that can be effective even if they are limited in duration. Here, the authors derive analytically optimal and near-optimal time-limited strategies for limiting the epidemic peak in the Susceptible-Infectious-Recovered model and show that, due to the sensitivity of such strategies to implementation errors, timely action is fundamental to non-pharmaceutical disease control.

It is generally accepted that the Universe is dominated by dark energy but the different methods to measure the Hubble constant disagree, giving origin to what is known as the "Hubble tension”. The authors demonstrate that the sole reduction of the sound horizon is not sufficient to fully resolve the Hubble tension.

Thin-film lithium niobate is a promising photonic platform owing to its strong optical nonlinearity and low losses. Here, the utility of this platform is demonstrated as a tunable dual frequency comb spectrometer based on second-order nonlinearities in a proof-of-principle experiment.

Microswimmers are ubiquitous in nature and present highly-dynamic collective motion. This study presents computational simulations of spheroidal model-microswimmers confined between two walls, revealing two collective dynamic states, giant motile clusters and active turbulence, depending on density and hydrodynamic interactions.

A crumpled sheet of paper is a common image in many contexts but crumpling dynamics are considered a complex problem. Using Mylar sheets the authors experimentally show that the evolution of the damage network in crumpling dynamics is largely history independent and the accumulation rate of the total length of all creases can be accurately predicted.

Skyrmions are magnetic topological features which are expected to play an important role in future data storage and information processing devices. The authors outline a theoretical method to calculate the size and wall width of an isolated skyrmion.

Secure transfer of quantum information is of importance for the development of quantum technology such as quantum communication and storage. Here, the authors use carbon nuclear spins coupled to a nitrogen vacancy center to achieve reliable quantum state transfer of photon polarization.

Thunderstorms are thought to produce two types of high-energy emissions, terrestrial gamma-ray flashes and gamma-ray glows however due to the difficulty in their observation the exact relation between the two is still not well-understood. Here, the authors report the simultaneous detection of a gamma-ray glow and a downward terrestrial gamma-ray flash suggesting the origin of the two phenomena are related.

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.

Twitter is becoming increasingly influential in the global political panorama. Here, the authors take a complex networks approach to study the Twitter debate around the Italian migrant crisis, finding evidence for "bots squads” amplifying the tweets of a few key political figures.

When watching a movie of a physical process, one can conjecture whether it is running forward or backward in time by examining key physical parameters in the process. Here, the authors show that superpositions of (thermodynamic) quantum processes with opposite time’s arrows are also physically possible and observable, and explore the thermodynamic role played by the interference term.

Electron-positron pair generation from nonlinear quantum electrodynamics is predicted at high intensities that are, so far, beyond experimental capabilities. Here, simulations predict a high yield of positrons can be obtained from gamma-gamma photon collisions in the linear regime, using counter-propagating pulses and a microstructured target.

In quantum physics, observables are generally believed to be Hermitian, but there are several examples of non-Hermitian systems possessing real positive eigenvalues, particularly among open systems. Here, the authors simulate the evolution of a non-Hermitian Hamiltonian on a superconducting quantum processor using a dilation procedure involving an ancillary qubit, and observe the parity–time (PT)-symmetry breaking phase transition at the exceptional points.

The genetic stability of DNA suffers from proton transfer along the hydrogen bonds that can lead to tautomerisation, creating mutations. The authors theoretically examine the tautomerisation of the GuanineCytosine (G-C) nucleotide base-pair using an open quantum systems approach, finding that the contribution of quantum tunnelling to the reaction rate outweighs classical barrier-hopping.

Different models exist to characterize magnetic reconnection, a process that converts magnetic energy into plasma thermal and kinetic energy, but a quantitative theoretical predictive model of how rapidly it proceeds has been lacking. Here, a self-consistent theory of the reconnection rate derived from first principles, and confirmed with numerical simulations, provides a new understanding of reconnection in solar flares and geomagnetic substorms.

To which extent and how do jazz musicians synchronize their timing to create swing? By analyzing jazz musical recordings and carrying out psychoacoustical experiments, the authors tackle a long-standing controversial question and find that microtiming deviations in the form of downbeat delays are a key component of swing in jazz.