Research articles

For hard Quantum Annealing problems, starting from the ground state might result into high failure probability due to nonadiabatic transitions where the quantum system leaves the ground state. Here, the authors propose an "excited-state" quantum annealing where a driven system starts in its vacuum state set to an effective excited state, and show that this approach is successful in reducing the failure probability.

The way interactions at the microscopic scale influence emerging flow properties in complex fluids at the macroscopic scale is one of the core problems in soft matter physics. This work provides experimental evidence together with a theoretical explanation for ‘Oobleck waves’, an instability arising from the coupling between the flow free surface and the non-monotonic rheological laws of shear-thickening suspensions.

Recently, inductively-coupled optomechanical systems have been realized. They represent an important step forward towards achieving strong light-matter interaction, offer extreme sensitivity to mechanical displacement, and allow to study quantum phenomena on a single quantum level. In this work, a superconducting device is inductively coupled to a microwave resonator forming an electromechanical system operating at the single-photon level.

Domain walls are the basic building blocks of a ferroic system and determine the overall ferroic properties. Here, the authors use aberration corrected scanning transmission electron microscopy to observe the formation of charged needle point domain walls in ferroelectric PbTiO₃ and how their characteristics depend on the lead vacancy concentration.

Coupling submicrometer mechanical elements such as nanowires to optical cavities is technically challenging because of the size difference between the resonators. Here, the authors demonstrate cavity optomechanical coupling of a nanowire mechanical resonator to an optical microsphere through near-field evanescent gradient forces and fine-tuning of resonance properties.

Understanding the spin-wave excitations of chiral magnetism is important to confirm such exotic magnetic order. Here, the authors obtain the spin wave spectrum for a given magnetic structure from Monte Carlo simulations and analyse the signatures when a ferromagnetic film undergoes a transition from a skyrmion crystal to a helical phase.

Ultrafast optical manipulation of excitons in semiconductor nanostructures offers practical access to quantum phenomena in condensed matter. The authors demonstrate a new scheme to control the exciton dephasing in large ensembles of quantum dots by application of resonant optical pulses that enable promising routes in the quest for quantum memories for information and communication technologies.

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.

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.

By interfacing graphene with other materials it is possible to break the intrinsic inversion symmetry and observe interesting quantum transport phenomena. Here, the authors conduct transport measurements of encapsulated graphene at different alignment angles and find evidence of nonlocal resistance above and below 60 K suggesting the existence of a quantum valley Hall state.

A wide variety of processes in nature and engineering ranging from rainfall and evaporation in soils to flow reversals in enhanced oil recovery and CO₂ geosequestration exhibit hysteresis, multivaluedness, and memory in the imbibition/drainage cycles. Here, the authors investigate the origins of these phenomena by developing a model based on first principles that, by accounting for the impact of pore space microstructure, provides a link between microscopic capillary heterogeneity and large-scale hysteresis in pressure-saturation curves.

The applicability of high-resolution mass measurements of optically trapped particles is currently limited by experimental constraints, with no access the lower picogram range. Here, the authors propose a broadly applicable optical balance to accurately weigh submicron aerosol droplets down to the picogram level.

The calculation of the topological invariants of non-Hermitian systems typically relies on the natural modes of the system. Here, an alternative method is presented which does not require the knowledge of the band structure, based on the Green’s function.

A quantum phase transition describes a phase change that occurs at zero temperature and involves collective quantum interactions that are thought to be independent of the system’s boundaries. Here, the authors theoretically demonstrate a quantum phase transition in an antiferromagnetic 1D spin chain, which can occur if the chain is constrained to frustrated boundary conditions, and that is driven by changing the subdominant interaction from ferromagnetic to antiferromagnetic.

While first order phase transitions between incoherence and synchronization are critical for collective behavior in various oscillator system application, e.g., the brain and power grids, such transitions typically require finely tuned properties. In this work the authors show that first order phase transitions and bistability can emerge naturally as a consequence of the presence of higher-order interactions between oscillators.

Precise electrical control of magnetic states in interacting nanomagnetic arrays is a requirement for these devices to be suitable for versatile low-power applications. Here, using simulations, the authors demonstrate reversible control of magnetic nanoislands using the current driven motion of a domain wall in an adjacent nanowire.

Under extreme conditions, nonlinear lattice dynamics in a material can manifest and reveal unexpected properties. Here, using inelastic neutron scattering and first-principles calculations the authors find the presence of nonlinear travelling waves in a fluorite structured system, which exhibit characteristics different from regular phonons.

Theoretical descriptions of photonic networks become increasingly complex as nonlinear, multimode systems are considered. Here, a statistical approach to determining the optical entropy of complex photonic chain networks is presented.

Studying the evolution of the network of amicable and hostile relations between countries allows powerful insights into global events such as the origin of wars, economy collapses, and the result of political elections. Here, the authors study 23 years of event data for international appraisals and find that the evolution of the corresponding network is consistent with structural balance theory, with triadic interactions evolving towards balanced relationships.

Second-order nonlinear optical processes are known to occur at the surface of centrosymmetric metals where quantum effects could be crucial for an accurate description of electron dynamics. Here, the authors develop a theoretical model based on quantum hydrodynamic theory which efficiently describes the complex nonlinear electron dynamics at the metal surface and predicts spill-out induced strong resonances in the second-harmonic generation efficiency spectra.