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The system of a transversely pumped Bose-Einstein condensate (BEC) coupled to a lossy ring cavity can favor a supersolid steady state. Here we find the existence of supersolid gap soliton in such a driven-dissipative system. By numerically solving the mean-field atom-cavity field coupling equations, gap solitons of a few different families have been identified. Their dynamical properties, including stability, propagation, and soliton collision, are also studied. Due to the feedback atom-intracavity field interaction, these supersolid gap solitons show numerous new features compared with the usual BEC gap solitons in static optical lattices.

Background. Metagenomic next-generation sequencing (mNGS) has made a revolution in the mode of pathogen identification. We decided to explore the diagnostic value of blood and bronchoalveolar lavage fluid (BALF) as mNGS samples in pneumonia. Methods. We retrospectively reviewed 467 mNGS results and assessed the diagnostic performance of paired blood and BALF mNGS in 39 patients with pneumonia. Results. For bacteria and fungi, 16 patients had culture-confirmed pathogen diagnosis, while 13 patients were culture-negative. BALF mNGS was more sensitive than blood mNGS (81.3% vs. 25.0%, p=0.003), and the specificity in BALF and blood mNGS was not statistically significant different (76.9% vs. 84.6%, p=0.317). For 10 patients without culture test, treatments were changed in 2 patients. For viruses, Epstein-Barr virus was positive in blood mNGS in 9 patients. Human adenovirus was detected in both BALF and blood mNGS in 3 patients. Conclusion. Our study suggests that BALF mNGS is more sensitive than blood mNGS in detecting bacteria and fungi, but blood also has advantages to identify the pathogens of pneumonia, especially for some viruses.

Memristive synapses from biomaterials are promising for building flexible and implantable artificial neuromorphic systems due to their remarkable mechanical and biological properties. However, these biological devices have relatively poor memristive switching characteristics, and thus fail to meet the requirement of neuromorphic networks for high learning accuracy. Here, memristive synapses based on carrageenan nanocomposites that possess desirable characteristics are demonstrated. These devices show highly reproducible analog resistive switching behaviors with 250 conductance states, low write noise, good write linearity, high retention of more than 104 s and endurance for at least 106 pulses. The enhanced switching properties are attributed to controllable and confined conductive filament growth, owing to the synergistic effect of self-assembled silver nanocluster doping and nanocone-shaped electrode contact. Moreover, the devices exhibit excellent reliability after 1000 bending cycles. Simulations including the non-ideal factors prove that the synaptic device array can operate with an online learning accuracy of 94.3%. These findings enable broader applications of biomaterials in flexible memristive devices and neuromorphic systems.

Electronic synapses based on memristive devices can potentially open a niche area for neuromorphic computing by replicating the function of biological synapses with high fidelity. Recently, two-terminal memristors based on halide perovskites have demonstrated outstanding memristive properties and a variety of synaptic characteristics, combining with their additional advantages such as a solution-processed fabrication method and low crystalline temperature. However, the concerns over the chemical and phase stability of halide perovskites greatly hinder their practical applications. In this study, by using a simple single-step spin-coating method, we report artificial synapses with superior ambient stability (>90 days under ambient conditions) based on fully inorganic nonperovskite δ-phase CsPbI3 in a cross-bar array architecture. The threshold switching memristive device exhibits a moderate ON/OFF ratio, a relatively low operation voltage (0.3 V) and high endurance (>5 × 105). More importantly, the electronic device can emulate synaptic characteristics such as short-term plasticity, paired-pulse facilitation, and the transition from short-term memory to long-term memory with a high output signal-to-noise ratio (>102). This work represents the first record for artificial synapses based on nonperovskite CsPbI3 and will be a step toward achieving low-cost and high-density practical synapse arrays.

We studied a system of atomic Bose-Einstein condensate coupled to a ring cavity within the mean-field theory. Due to the interaction between atoms and light field, the atoms can be self-trapped. This is verified with both variational and numerical methods. We examined the stability of these self-trapped states. For a weakly pumped cavity, they spread during the evolution; while at strong pumping, they can maintain the shape for a long time. We also studied the moving dynamics of these self-trapped waves, and found out that it can be strongly affected by the cavity decay rate. For a small cavity decay rate, the self-trapped waves undergo a damped oscillation. Increasing the cavity decay rate will lead to a deceleration of the self-trapped waves. We also compared the main results with the semiclassical theory in which atoms are treated as classical particles.

We study the transport of a spin-orbit-coupled atomic matter wave using a moving Dirac $\ensuremath{\delta}$-potential well. In a spin-orbit-coupled system, bound states can be formed in both ground and excited energy levels with a Dirac $\ensuremath{\delta}$ potential. Because Galilean invariance is broken in a spin-orbit-coupled system, moving of the potential will induce a velocity-dependent effective detuning. This induced detuning breaks the spin symmetry and makes the ground-state transporting channel be spin-$\ensuremath{\uparrow}$ ($\ensuremath{\downarrow}$) favored while makes the excited-state transporting channel be spin-$\ensuremath{\downarrow}$ ($\ensuremath{\uparrow}$) favored for a positive-direction (negative-direction) transporting. When the $\ensuremath{\delta}$-potential well moves at a small velocity, both the ground-state and the excited-state channels contribute to the transportation, and thus both the spin components can be efficiently transported. However, when the moving velocity of the $\ensuremath{\delta}$-potential well exceeds a critical value, the induced detuning is large enough to eliminate the excited bound state, and makes the ground bound state the only transporting channel, in which only the spin-$\ensuremath{\uparrow}$ ($\ensuremath{\downarrow}$) component can be efficiently transported in a positive (negative) direction. This work demonstrates a prototype of unidirectional spin transport.

Background Idiopathic pulmonary fibrosis (IPF) is a serious disorder with a high mortality rate worldwide. It is characterized by irreversible scarring of the lung parenchyma resulting from excessive collagen production by proliferating fibroblasts/myofibroblasts. Previous studies have revealed that mutations in surfactant protein‐related genes and telomerase complex genes are crucial underlying genetic factors. Methods In this study, we enrolled a family with IPF from the central southern region of China. Whole‐exome sequencing was employed to explore candidate genes in this family. Real‐time PCR and western blotting were used to study the functions of the identified mutations in vitro. Results A novel mutation (NM_001098668.4: c.619A>T; NP_001092138.1: p.N207Y) in surfactant protein A2 (SFTPA2,), having not been previously reported to be a mutation, was identified and co‐separated with all affected individuals in the IPF family. Functional research further revealed that the novel mutation affects the secretion of SFTPA2 protein and induces endoplasmic reticulum stress as well as apoptosis in A549 cells. Conclusion We are confident that this novel mutation (NM_001098668.4: c.619A>T; NP_001092138.1: p.N207Y) in SFTPA2 is the genetic mutation of the IPF family. Our study not only confirms the importance of SFTPA2 in IPF but also expands the spectrum of SFTPA2 mutations and contributes to the genetic diagnosis and counseling of IPF patients., Mutation in SFTPA2 was rare reported, and we identified a novel pathogenic mutation (p.N207Y) of SFTPA2 gene in idiopathic pulmonary fibrosis (IPF) patients in this study. Functional study further confirmed the novel mutation may affect the expression and secretion of surfactant protein A2 protein and induce endoplasmic reticulum stress and apoptosis. Our study not only confirmed the importance of SFTPA2 in IPF, but also expanded the spectrum of SFTPA2 mutations and contributed to the genetic diagnosis and counseling of IPF patients.

In this work we study the model of flux lattice, specifically a two-leg Bose–Hubbard ladder lattice subject to effective magnetic flux, which can be implemented using spin–orbit coupled cold atoms trapped in an optical lattice. This model has attracted much recent research interest due to that it provides a platform to study the interplay between artificial gauge fields and interactions. We consider that collective dipole oscillations are activated in this model via quenching an external harmonic trapping potential and show that this system can exhibit unique dynamical behaviors in terms that oscillation amplitude and period critically dependent on the spin–orbit coupling. A dynamical slowing down in collective dipole oscillations will take place near the transition point between the Meissner superfuild and vortex superfluid phases, which agrees quantitatively with a variational analysis. We show that such a quantum phase transition can also be probed via the damping of the collective dipole oscillation. When the quenching displacement is large, the collective center-of-mass motion behaves as damped oscillation and the damping reaches its maximum near the phase transition point. The specific dynamical phenomena are explained with eigenspectra and level populations after the quenching. In the presence of interactions, the time-dependent density–matrix renormalization group (tDMRG) method is hired to study the collective dynamics. The case with weak interactions is similar to that without interactions, except that interactions tend to enhance damping. In addition to that, Bragg reflection can be observed when the quenching displacement exceeds a critical value. The case with strong interactions is also studied, in which case the phase transition points will be dramatically changed and the system can even move into the Mott insulator phase, which will greatly affect the corresponding collective dynamics. The phenomena predicted in this work can be readily observed in current available experiments on atom flux lattices. •The two-leg ladders subject to magnetic flux with a trap show diverse dynamics.•The tDMRG method is employed to research the non-equilibrium dynamics.•Due to the existence of SOC, dipole oscillations behave odd in short time evolution.

Self-accelerating waves in conservative systems, which usually feature slowly decaying tails, such as Airy waves, have drawn great interest in studies of quantum and classical wave dynamics. They typically appear in linear media, while nonlinearities tend to deform and eventually destroy them. We demonstrate, by means of analytical and numerical methods, the existence of robust one- and two-dimensional (1D and 2D) self-accelerating tailless solitons and solitary vortices in a model of two-component Bose-Einstein condensates, dressed by a microwave (MW) field, whose magnetic component mediates long-range interaction between the matter-wave constituents, with the feedback of the matter waves on the MW field taken into account. In particular, self-accelerating 2D solitons may move along a curved trajectory in the coordinate plane. The system may also include the spin-orbit coupling between the components, leading to similar results for the self-acceleration. The effect persists if the contact cubic nonlinearity is included. A similar mechanism may generate 1D and 2D self-accelerating solitons in optical media with thermal nonlinearity., Comment: Accepted by Phys. Rev. A

We theoretically investigate quantum tunnelling escape of a spin-orbit (SO) coupled Bose-Einstein condensate (BEC) from a trapping well. The condensate is initially prepared in a quasi-one-dimensional harmonic trap. Depending on the system parameters, the ground state can fall in different phases --- single minimum, separated or stripe. Then, suddenly the trapping well is opened at one side. The subsequent dynamics of the condensate is studied by solving nonlinear Schr\"{o}dinger equations. We found that the diverse phases will greatly change the tunneling escape behavior of SO coupled BECs. In single minimum and separated phases, the condensate escapes the trapping well continuously, while in stripe phase it escapes the well as an array of pulses. We also found that SO coupling has a suppressing effect on the tunnelling escape of atoms. Especially, for BECs without inter-atom interaction, the tunnelling escape can be almost completely eliminated when the system is tuned near the transition point between single minimum and stripe phase. Our work thus suggests that SO coupling may be a useful tool to control the tunnelling dynamic of BECs, and potentially be applied in realization of atom lasers and matter wave switches., Comment: to be published in J. Phys. B: At. Mol. Phys

Non-spreading wave packets and matter-wave packets in ring traps both have attracted great research interests due to their miraculous physical properties and tempting applications for quite a long time. Here, we proved that there exists only one set of non-spreading matter-wave packets in a free ring, and this set of wave packets have been found analytically. These non-spreading matter-wave packets can be realized in a toroidal trapped Bose-Einstein condensate system with the help of Feshbach resonance to eliminate contact interaction between atoms. Since experimentally residual interaction noise will always exist, its effect on the stability of these non-spreading wave packets is also examined. Qualitatively, under weak residual interaction noise, these non-spreading wave packets can preserve their shape for quite a long time, while a stronger interaction noise will induce shape breathing of the wave packets. Shape-keeping abilities of these wave packets are further studied quantitatively. We found that this set of wave packets have the same shape-keeping ability against interaction noise. And, the shape-keeping ability is linearly related to the interaction noise strength.

Stable self-trapped vortex annuli (VAs) with large values of topological charge S (giant VAs) are not only a subject of fundamental interest, but are also sought for various applications, such as quantum information processing and storage. However, in conventional atomic Bose-Einstein condensates (BECs) VAs with S>1 are unstable. Here, we demonstrate that robust self-trapped fundamental solitons (with S=0) and bright VAs (with the stability checked up to S=5), can be created in the free space by means of the local-field effect (the feedback of the BEC on the propagation of electromagnetic waves) in a condensate of two-level atoms coupled by a microwave (MW) field, as well as in a gas of MW-coupled fermions with spin 1/2. The fundamental solitons and VAs remain stable in the presence of an arbitrarily strong repulsive contact interaction (in that case, the solitons are constructed analytically by means of the Thomas-Fermi approximation). Under the action of the moderate attractive contact interaction which, by itself, would lead to collapse, the fundamental solitons and VAs exist and are stable, respectively; it is interesting that higher-order VAs are more robust than their lower-order couterparts, on the contrary to what is known in other systems that may support stable self-trapped vortices. Conditions for the experimental realizations of the VAs are discussed., 7 pages, 6 figures, Physical Review A, in press

It was recently found that the electric local-field effect (LFE) can lead to a strong coupling of atomic Bose-Einstein condensates (BECs) to off-resonant optical fields. We demonstrate that the magnetic LFE gives rise to a previously unexplored mechanism for coupling a (pseudo-) spinor BEC or fermion gas to microwaves (MWs). We present a theory for the magnetic LFE and find that it gives rise to a short-range attractive interaction between two components of the (pseudo) spinor, and a long-range interaction between them. The latter interaction, resulting from deformation of the magnetic field, is locally repulsive but globally attractive, in sharp contrast with its counterpart for the optical LFE, produced by phase modulation of the electric field. Our analytical results, confirmed by the numerical computations, show that the long-range interaction gives rise to modulational instability of the spatially uniform state, and it creates stable ground states in the form of hybrid matter-wave-microwave solitons (which seem like one-dimensional magnetic monopoles), with a size much smaller than the MW wavelength, even in the presence of arbitrarily strong contact intercomponent repulsion. The setting is somewhat similar to exciton-polaritonic condensates in semiconductor microcavities. The release of matter waves from the soliton may be used for the realization of an atom laser. The analysis also applies to molecular BECs with rotational states coupled by the electric MW field.

We consider a matter wave packet of cold atom gas impinging upon a step potential created by the optical light field. In the presence of spin-orbit (SO) coupling, the atomic eigenstates contain two types of evanescent states, one of which is the ordinary evanescent state with pure imaginary wave vector while the other possesses complex wave vector and is recognized as oscillating evanescent state. We show that the presence and interplay of these two types of evanescent states can give rise to two different mechanisms for total internal reflection (TIR), and thus lead to unusual Goos-H\"anchen (GH) effect. As a result, not only large positive but also large negative GH shift can be observed in the reflected atomic beam. The dependence of the GH shift on the incident angle, energy and height of the step potential is studied numerically.