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Magnonics is a research field complementary to spintronics, in which the quanta of spin waves (magnons) replace electrons as information carriers, promising lower dissipation1–3. The development of ultrafast, nanoscale magnonic logic circuits calls for new tools and materials to generate coherent spin waves with frequencies as high and wavelengths as short as possible4,5. Antiferromagnets can host spin waves at terahertz frequencies and are therefore seen as a future platform for the fastest and least dissipative transfer of information6–11. However, the generation of short-wavelength coherent propagating magnons in antiferromagnets has so far remained elusive. Here we report the efficient emission and detection of a nanometre-scale wavepacket of coherent propagating magnons in the antiferromagnetic oxide dysprosium orthoferrite using ultrashort pulses of light. The subwavelength confinement of the laser field due to large absorption creates a strongly non-uniform spin excitation profile, enabling the propagation of a broadband continuum of coherent terahertz spin waves. The wavepacket contains magnons with a shortest detected wavelength of 125 nm that propagate into the material with supersonic velocities of more than 13 km s–1. This source of coherent short-wavelength spin carriers opens up new prospects for terahertz antiferromagnetic magnonics and coherence-mediated logic devices at terahertz frequencies.Ultrashort light pulses generate nanometre-scale wavepackets of magnons that propagate coherently and at high speed in an antiferromagnet. This pushes antiferromagnetic magnonics forward as a future platform for information processing.

A boson two-leg ladder in the presence of a synthetic magnetic flux is investigated by means of bosonization techniques and density matrix renormalization group (DMRG). We follow the quantum phase transition from the commensurate Meissner to the incommensurate vortex phase with increasing flux at different fillings. When the applied flux is π and close to it, where is the filling per rung, we find a second incommensuration in the vortex state that affects physical observables such as the momentum distribution, the rung-rung correlation function and the spin-spin and charge-charge static structure factors.

In this work we address the study of topological phase protection of open quantum systems. Using the self-energy formalism, we investigate the paradigmatic case of an extended Kitaev model. The results show how the topological order can be affected by coupling the system to two external leads, giving rise to Non-Hermitian topological phases. Our results could be useful in spectroscopic measurements made on nanowire-based mesoscopic devices.

Since the 80 s when it was first proposed, Quantum Key Distribution (QKD) elicited great interest in the field of cryptography as a unique procedure for key generation that could in principle guarantee unconditionally secure communication “by the laws of Physics”. In the last fifteen years commercial solutions have started appearing on the market, showing that practical implementations of the protocol were not only possible but also competitive in terms of security and achievable secret-key rate. In this work we describe a simulation of the historical QKD protocol E91 on the IBM Quantum platform, making use of the qubit formalism to represent the quantum states received by two communicating nodes. Having implemented also the post-processing steps for the error correction and the privacy amplification, this model can represent a simple stand-alone tool to study the performance not only of one-to-one communication but of more complex systems that rely on QKD for security, one above all QKD networks.

Using the IBM Quantum Experience platform, we simulate the dissipative dynamics in the BB84 quantum key distribution protocol. We employ the Jaynes–Cummings model to simulate the attenuation in an optical fiber during the information transmission process and calculate the quantum bit error rate (QBER). The results of QBER as a function of the distance give a satisfactory agreement with experimental data when the system is in a Markovian regime.

We investigate the topological properties of a ladder given by two one dimensional p-wave superconductors coupled together site to site by transversal hopping t. For small t, we also derive an effective model whose simpler form is feasible to implement some braiding procedures proposed in the literature.

Molecular mechanisms protecting cardiomyocytes from stress-induced death, including tension stress, are essential for cardiac physiology and defects in these protective mechanisms can result in pathological alterations. Bcl2-associated athanogene 3 (BAG3) is expressed in cardiomyocytes and is a component of the chaperone-assisted autophagy pathway, essential for homeostasis of mechanically altered cells. BAG3 ablation in mice results in a lethal cardiomyopathy soon after birth and mutations of this gene have been associated with different cardiomyopathies including stress-induced Takotsubo cardiomyopathy (TTC). The pathogenic mechanism leading to TTC has not been defined, but it has been suggested that the heart can be damaged by excessive epinephrine (epi) spillover in the absence of a protective mechanism. The aim of this study was to provide more evidence for a role of BAG3 in the pathogenesis of TTC. Therefore, we sequenced BAG3 gene in 70 TTC patients and in 81 healthy donors with the absence of evaluable cardiovascular disease. Mutations and polymorphisms detected in the BAG3 gene included a frequent nucleotide change g2252c in the BAG3 3′-untranslated region (3′-UTR) of Takotsubo patients ( P <0.05), resulting in loss of binding of microRNA-371a-5p (miR-371a-5p) as evidenced by dual-luciferase reporter assays and argonaute RNA-induced silencing complex catalytic component 2/pull-down assays. Moreover, we describe a novel signaling pathway in cardiomyocytes that leads to BAG3 upregulation on exposure to epi through an ERK-dependent upregulation of miR-371a-5p. In conclusion, the presence of a g2252c polymorphism in the BAG3 3′-UTR determines loss of miR-371a-5p binding and results in an altered response to epi, potentially representing a new molecular mechanism that contributes to TTC pathogenesis.

The reported ranges of aortic root (AR) diameters are limited by small sample size, different measurement sites, and heterogeneous cohorts. The aim of this study was to explore the full spectrum of AR diameters by 2-dimensional transthoracic color Doppler echocardiography (TTE) in a large cohort of healthy adults. From June 2007 to December 2013, a total of 1,043 Caucasian healthy volunteers (mean age 44.7 ± 15.9 years, range 16 to 92 years, 503 men [48%]) underwent comprehensive TTE. TTE measurements of the AR were made at end-diastole in parasternal long-axis views at 4 levels: (1) annulus, (2) sinuses of Valsalva, (3) sinotubular junction, and (4) proximal ascending aorta. The absolute aortic diameters were significantly greater in men than in women at all levels, whereas body surface area–indexed aortic diameters were greater in women (p = 0.0001). No significant gender differences were registered for sinuses of Valsalva and sinotubular junction to annulus diameter ratios (p = 0.9), whereas ascending aorta to annulus diameter ratio was higher in women (p = 0.0001). There was a straight correlation between aortic diameters (absolute and indexed values), their ratios, and age in both genders (p = 0.0001). In conclusion, we provide the full range of AR diameters by TTE. Knowledge of upper physiological limits of aortic dimensions is mandatory to detect aorta dilatation, follow up the disease over time, and plan appropriate therapeutic interventions.

Lattice and charge degrees of freedom of cuprate superconductors remain an intensively debated topic, both experimentally and theoretically, because of the strong anomalies observed in some of the phonon branches. In particular, the bond-stretching phonon modes show a knee like softening and a large damping for momenta around 0.25–0.3 r.l.u. along, e.g., (1, 0, 0) direction of the Brillouin zone. We discuss a phenomenological model where these anomalies are caused by coupling to electron charge fluctuations and explore a possibility to extract the spectrum of the latter from the phonon data. In particular, we predict a significant deviation from the standard value of the oxygen isotope substitution effect on the phonon spectrum itself. The phonon dispersion and linewidth are shown to contain complementary information related to the isotope effect which could allow a detailed description of the electronic spectrum.