Table of contents

We study the continuous variable entanglement of a system of two particles under the influence of the Earth's gravitational field. We determine a phase-space description of this bipartite system by calculating its Wigner function and verify its entanglement by applying a generalization of the PPT criterion for non-Gaussian states. We also examine the influence of gravity on entangled states at different potentials based on the correlation of states of the gravitational quantum well.

A fluctuation theorem (FT), both classical and quantum, describes the large-deviations in the approach to equilibrium of an isolated quasi-integrable system. Two characteristics make it unusual: i) it concerns the internal dynamics of an isolated system without external drive, and ii) unlike the usual FT, the system size, or the time, need not be small for the relation to be relevant, provided the system is close to integrability. As an example, in the Fermi-Pasta-Ulam chain, the relation gives information on the ratio of probability of death to resurrection of solitons. For a coarse-grained system the FT describes how the system "skis" down the (minus) entropy landscape: always descending but generically not along a gradient line.

It has been suggested that surface acoustic waves can couple remote quantum bits (qubits). Bulk diamond and chemical vapor deposition diamond films host the negatively charged nitrogen-vacancy color center (NV⁻¹) which carry an electronic spin-1. The latter is among the most promising qubits for implementing scalable quantum information processing. The characteristic features of the Rayleigh surface acoustic wave which can propagate near the free surface of a diamond thin film are investigated. The texture of the film is taken into account. A phenomenological theory of the spin-phonon interaction is applied to describe the coupling between the Rayleigh surface acoustic wave and the NV⁻¹ spin-qubits.

We study the impact of Lorentz-violating terms on a physical observable for both electrodynamics of chiral matter and an Abelian Higgs-like model in $3+1$ dimensions. Our calculation is done within the framework of the gauge-invariant, but path-dependent, variables formalism. Interestingly enough, for electrodynamics of chiral matter we obtain a logarithmic correction to the usual static Coulomb potential. Whereas for an Abelian Higgs model with a Lorentz-breaking term, our result displays new corrections to the Yukawa potential.

The α-decay is considered as a superasymmetric fission process. A fragmentation path is obtained by mean of the least action principle in a configuration space spanned by five degrees of freedom. The potential barrier is obtained within the macroscopic-microscopic model while the effective mass and the momentum of inertia within the cranking approach. The single-particle wave functions and the single-particle energies are supplied by the Woods-Saxon two-center shell model. The fine structure of ²¹¹Bi α-decay is treated within a set of generalized time-dependent pairing equations that takes into account the Landau-Zener effect and the Coriolis coupling. A low value of the internuclear collective velocity was used. The theoretical results showed a good agreement with the experimental data. Essentially, in the framework of the formalism, the fine structure for the ²¹¹Bi is due to the occurrence of the Coriolis coupling.

We report the onset of elastic turbulence in a two-dimensional Taylor-Couette geometry using numerical solutions of the Oldroyd-B model generated with the program OpenFOAM^®. Beyond a critical Weissenberg number, an elastic instability causes a supercritical transition from the laminar Taylor-Couette flow to a turbulent flow. The order parameter, the time average of secondary-flow strength, follows the scaling law $\Phi \propto (\mathrm{Wi} -\mathrm{Wi}_c)^{\gamma}$ with $\mathrm{Wi}_c=10$ and $\gamma = 0.45$. Additionally, the flow resistance increases beyond Wi_c. The temporal power spectra of the velocity fluctuations show a power-law decay with a characteristic exponent in the range $2< \alpha < 4$, which strongly depends on the radial position. The characteristic exponent β for the spatial power spectra obeys the necessary condition $\beta > 3$, associated with elastic turbulence, for all $\mathrm{Wi} > \mathrm{Wi}_c$.

The cavity ringing phenomenon is vital in both fundamental research and applications such as in the rapid detection and transient sensing. Here we report a novel method —the combination of the optothermal scanning method and Raman gain to achieve and control the ringing effect in a silica optical microsphere. Comparing to the usual method requiring laser sweeping, this method does not require sweeping the probe laser, which makes it easier and more stable in applications. The ringing strength can be easily controlled by adjusting the frequency detuning of the probe laser and changing the scanning speed of the pump laser. In particular, our dynamic models can fit well with the experimental results. This letter shows that the optothermal control of ringing is robust to external fluctuations, which can enhance the performance and stability of the transient microcavity sensors.

Metasurface is emerging as an important platform to design various functional devices due to the superior capability in controlling amplitude, phase and polarization of light through its ultrathin engineering interface. A polarized-selective hologram of all-dielectric metasurface is proposed to reconstruct multiplexed holographic images on different linear polarization status. Unlike early metasurfaces composed of plasmonic resonators with great ohmic loss at visible spectrum, the designed metasurface made of silicon nanoblocks supports a broader spectral response over the bandwidth from 600 to 760 nm with high diffraction efficiency and low crosstalk between different polarization states. Both simulation and experiment have demonstrated the feasibility and adjustability of the polarization-multiplexed metasurface hologram. We believe it will have significant technological potential in the design of optical functional devices.

We analyze the steric effect of electrolyte on the normal stress exerted on a wall and the free charge density in a nanoconfinement using the modified Poisson-Boltzmann (mPB) equation. The outward normal stress exerted on the channel wall (P_nn) is calculated by solving the mPB numerically with a constant surface potential for various equilateral polygonal channels and compared with one-dimensional and circular channels by varying the steric factor (γ) and asymmetry of ions (ξ). The results show that the averaged normal stress on the walls ($\overline{P_{nn}}$) and the averaged charge density in the channels ($\overline{\rho}$) are almost independent of the channel shape, and are the same with those of the circular channel. From the numerical observation, we infer the universality of average electric field ($\overline{E_n}$) and average electrical stress ($\overline{E_{n}^{2}}$) on the channel wall, both of which are independent of the channel shape if the hydraulic radius is the same.

We use experiments and numerical simulations to study the rapid buckling of thin-walled cones as they impact a solid surface at high velocities. The buildup of air pressure inside the cone localizes the deformations to the impacting interface with the solid surface, leading to the hierarchical formation of an ordered pattern of small rhomboidal cells. In contrast, when the inner air pressure is not allowed to develop, the ordered pattern is destabilized and the cone collapses in a highly disordered state on long length scales. Numerical simulations confirm that the transition between ordered and disordered crumpling is governed by the competition between the elastic deformation energy of the shells and the work required to pressurize the air. Our results show how dynamic stabilization via tensioning suppresses long wavelength subcritical instabilities in shells and leads to the localization and propagation of short wavelength patterns.

We investigate Airy-soliton interactions in self-defocusing media with PT potentials in one transverse dimension. We discuss different potentials in which the interacting beams with different phases are launched into the media at different separation distances. During interactions, there exist a primary collision region and a relaxation region accompanied by continuous interaction with the dispersed Airy tail. In the relaxation region, the beams exist as soliton-like and breathers-like propagation. The beam width and mean power are influenced by initial separation, phase shift and modulation depth of PT potentials. Especially, the collision distance decreases with the spatial beam separation and the mean power possesses sinusoidal dependence on the phase shift.

The x-ray and gamma-ray flashes observed in the Earth atmosphere during a thunderstorm are usually associated with the generation of runaway electrons (RE) in atmospheric electric fields. It is supposed that runaway electron avalanches initiated by cosmic rays play the main role in high-altitude discharges observed in a thunderstorm atmosphere. We have performed three-dimensional numerical calculations to investigate the mechanism of the development of a critical avalanche and to determine its parameters. It has been shown that the number of electrons in a critical avalanche occurring in air under conditions characteristic of thunderstorm discharges can reach a value of the order of 10¹⁸.

It is well known that the contribution of harmonic phonons to the thermal conductivity of 1D systems diverges with the harmonic chain length L. Within various one-dimensional models containing disorder it was shown that the thermal conductivity scales as $\sqrt{L}$ under certain boundary conditions. Here we show that when the chain is weakly coupled to the heat reservoirs and there is strong disorder this scaling can be violated. We find a weaker power-law dependence on L, and show that for sufficiently strong disorder the thermal conductivity ceases to be anomalous – it does not depend on L and hence obeys Fourier's law. This is despite both density of states and the diverging localization length scaling anomalously. Surprisingly, in this strong disorder regime two anomalously scaling quantities cancel each other to recover Fourier's law of heat transport.

Spin-polarized electron momentum densities of Nd-doped nickel ferrites (Ni_1−xNd_xFe₂O₄ where $x= 0.12$, 0.24) at 8 and 300 K temperatures are presented. The measurements have been made using the magnetic Compton scattering set-up available at SPring-8, Japan. The site-specific spin moments which contribute to the formation of the total spin moment are deduced by decomposition of the magnetic Compton profile (MCP) into constituent profiles. An increase in the spin moment at Fe site and a reduction at Ni site with Nd doping, as revealed by MCP data, are explained on the basis of the cationic redistribution at octahedral and tetrahedral sites using x-ray photoelectron spectroscopy (XPS) analysis. The XPS measurements suggest the emergence of Fe²⁺ ions in Nd-doped samples to maintain the charge neutrality. It is found that the net spin moment at the Nd site is antiparallel to that at Ni and Fe sites. The orbital magnetic moment (deduced from the difference of magnetic Compton and total magnetization data) is also discussed.

We have investigated the transport properties of a Kane-Mele normal-superconductor (NS) nano-junction using the familiar Blonder-Tinkham-Klapwijk (BTK) theory. The effects of the Rashba and the intrinsic spin-orbit coupling are mimicked by the inclusion of different transition metal adatoms adsorbed in a graphene nanoribbon. Specifically, we have focussed on the Andreev reflection phenomena for a range of Rashba and intrinsic coupling strengths. We have computed the spin resolved tunneling conductance where we found that the conductance characteristics are very sensitive to the strengths of the spin-orbit couplings. Further an interesting interplay between the Rashba and the intrinsic spin-orbit couplings is observed and its effects on the tunneling conductance are explored in detail. The possibility of tuning the spin-orbit couplings via different metal adatoms provides an experimental handle for achieving tunable conductance properties of this Kane-Mele nano-junction.

The Kirchhoff-Helmholtz principle of least heat dissipation is applied in order to take into account the electrostatic screening in the derivation of the stationary states of the spin-Hall effect. Spin-orbit interaction, spin-flip relaxation, and charge accumulation are treated on an equal footing in the variational approach. It is shown that the electrostatic screening modifies the steady-state continuity equation due to the presence of surface currents, and that the stationary state defined by a linear spin-accumulation potential and zero pure spin current corresponds to the minimum power dissipated in the device.

Sr₂IrO₄ has been shown to host a novel $J_{\mathrm{eff}}=1/2$ Mott spin-orbit insulating state with antiferromagnetic ordering. Here, the effects of Sm substitution at Sr-site on structural, electrical and magnetic properties are studied in Sr₂IrO₄. Sm-doped samples still retain the insulating behavior, but with the increase of Sm-doping concentration x, the resistivity firstly decreases for $x \le 0.1$ and then increases. We found that the increment of the Ir-O-Ir bond angle, combined with the modulation of the regularity of IrO₆ octahedra, results in the non-monotonic variation of resistivity with x. On the other hand, there are two types of magnetic exchange interactions (i.e., Ir⁴⁺-O-Ir⁴⁺ and Sm³⁺-O-Ir⁴⁺) in the Sm-doped Sr_2−xSm_xIrO₄ system. The antiferromagnetic component is greatly suppressed in the low concentration x and then an ascension emerges in the high concentration x, which is attributable to the competition between the weakened Ir⁴⁺-O-Ir⁴⁺ and enhanced Sm³⁺-O-Ir⁴⁺ exchange interactions.

We investigate a novel way to manipulate the spin-polarized transmission in a two-terminal zigzag graphene nanoribbon in the presence of the Rashba spin-orbit (SO) interaction with a circular-shaped cavity engraved into it. A usual technique to control the spin-polarized transport behaviour of a nanoribbon can be achieved by tuning the strength of the SO coupling, while we show that an efficient engineering of the spin-polarized transport properties can also be done via cavities of different radii engraved in the nanoribbon. Simplicity of the technique in creating such cavities in the experiments renders an additional handle to explore transport properties as a function of the location of the cavity in the nanoribbon. Further, a systematic assessment of the interplay of the Rashba interaction and the dimensions of the nanoribbon is presented. These results should provide useful input to the spintronic behaviour of such devices. In addition to the spin polarization, we have also included an interesting discussion on the charge transmission properties of the nanoribbon, where, in the absence of any SO interaction a metal-insulator transition induced by the presence of a cavity is observed.

Strategy persistence has been found to play an important role in the emergence and maintenance of cooperation. In this work, we propose a spatial prisoner's dilemma game in which there are two types of individuals, P-individuals with nonzero strategy persistence level and NP-individuals without strategy persistence. We concern with the question: Who should P-individuals be if the goal is to achieve a high level of cooperation? By investigating four different schemes, i.e., uniform, inversely degree-related, degree-related, and collective influence schemes, we find that highly cooperative outcomes emerge if P-individuals are played by leaders with high degrees regardless of the structures of the underlying networks. In contrast, if the masses with low degrees act as P-individuals where leaders change their strategies frequently, cooperation cannot be promoted and, instead, it can even be weakened.

We propose a novel method of detecting directed interactions of a general dynamic network from measured data. By repeating random state variable resetting of a target node and appropriately averaging over the measurable data, the pairwise coupling function between the target and the response nodes can be inferred. This method is applicable to a wide class of networks with nonlinear dynamics, hidden variables and strong noise. The numerical results have fully verified the validity of the theoretical derivation.

Recent two-dimensional computer simulations and experiments indicate that even supercooled liquids exhibit long-lived, long-range strain correlations expected only in solids. Here we investigate this issue in three dimensions via Newtonian molecular-dynamics simulations, by a generalized hydrodynamics approach, and by experiments on Brownian hard-sphere colloids. Both in the glassy state and in liquid regimes, strain correlations are predicted to decay with a $1/r^3$ power law, reminiscent of elastic fields around an inclusion. In contrast, the temporal evolution of the correlation amplitude is distinct in the liquid state, where it grows linearly with time, and in the glass, where it reaches a time-independent plateau. These predictions are assessed via molecular-dynamics simulations and experiments. In simple liquids, the size of the cooperative strain patterns is of the order of the distance traveled by (high-frequency) transverse sound prior to structural relaxation. This length is of the order of nanometers in a normal liquid and grows to macroscale upon approaching the glass transition.

Complex ecosystems generally consist of a large number of different species utilizing a large number of different resources. Several of their features cannot be captured by models comprising just a few species and resources. Recently, Tikhonov and Monasson have shown that a high-dimensional version of MacArthur's resource competition model exhibits a phase transition from a "vulnerable" to a "shielded" phase in which the species collectively protect themselves against an inhomogeneous resource influx from the outside. Here we point out that this transition is more general and may be traced back to the existence of non-negative solutions to large systems of random linear equations. Employing Farkas' Lemma we map this problem to the properties of a fractional volume in high dimensions which we determine using methods from the statistical mechanics of disordered systems.

Using Principal Component Analysis (PCA), the nodal injection and line flow patterns in a network model of a future highly renewable European electricity system are investigated. It is shown that the number of principal components needed to describe 95% of the nodal power injection variance first increases with the spatial resolution of the system representation. The number of relevant components then saturates at around 76 components for network sizes larger than 512 nodes, which can be related to the correlation length of wind patterns over Europe. Remarkably, the application of PCA to the transmission line power flow statistics shows that irrespectively of the spatial scale of the system representation a very low number of only 8 principal flow patterns is sufficient to capture 95% of the corresponding spatio-temporal variance. This result can be theoretically explained by a particular alignment of some principal injection patterns with topological patterns inherent to the network structure of the European transmission system.

A Mix-phase MgZnO thin film was fabricated on the c-plane sapphire substrate (Mg_0.4Zn_0.6O target) under high laser energy density condition by the PLD method. The internal quantum efficiency of the detector based on the mix-phase MgZnO thin film at 230 nm deep UV light reached 86% at 40 V bias voltage. And the I_uv(230 nm)/I_dark ratio of the MgZnO detector reached 864 at 40 V bias voltage, which is mainly caused by both the higher internal gain of the detector at deep UV light and its smaller I_dark. The high internal gain of the detector is mainly due to the higher density of interfaces between the different structure of MgZnO grains in the mix-phase MgZnO thin film, which is caused by the higher laser energy density deposition condition certified by contrast experiments. The small I_dark of the detector is mainly caused by the higher barriers in the mix-phase MgZnO thin film and more cubic MgZnO in the mix-phase MgZnO thin film, and higher laser energy density deposition condition and O-rich c-plane sapphire substrate surface are key factors, which also agree with the contrast experiments results. So when the mix-phase MgZnO thin film that is constituted by both a small number of narrower band gap hexagonal MgZnO and a large number of wide band gap cubic MgZnO is used in the deep UV detector, and the difference in band gaps between different structures of MgZnO is relatively higher, a higher signal/noise ratio of the device at 230 nm deep UV light is gained, which is meaningful for developing high-performance deep UV detection technology.

We propose a model of rumor spreading in which susceptible, but skeptically oriented individuals may oppose the rumor. Resistance may be implemented either by skeptical activists trying to convince spreaders to stop their activity, becoming stiflers or, passively (non-reactive) as a consequence, for example, of fact-checking. Interestingly, these two mechanisms, when combined, are similar to the (assumed) spreading of a fictitious zombie outbreak, where survivors actively target infected people. We analyse the well-mixed (mean-field) description and obtain the conditions for rumors (zombies) to spread through the whole population. The results show that when the skepticism is strong enough, the model predicts the coexistence of two fixed points (such bistability may be related to polarized situations), with the fate of rumors depending on the initial exposure to it.

Analyticity constraints for hadron amplitudes Nonexistence of PT-symmetric gain-loss photonic quantum systems Signature of Fermi arc surface states in Andreev reflection Is the relation between mass and energy universal?