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The original formula to calculate the tunneling rate through event horizons is apparently dependent on the type of coordinates used. In this paper, we propose an invariant expression under canonical transformations to study the tunneling effect. Moreover, the problem of factor 2 is solved naturally. As an application of this expression, we obtain the same tunneling rate both in the Schwarzschild and the Painlevé coordinates. It is shown that once the suitable formula to calculate tunneling rate is correctly identified, the tunneling method is manifestly covariant. [ABSTRACT FROM AUTHOR]

By designing pivotal phase-only masks based on canonical catastrophe theory, finite-energy optical quinary-cusp beams are experimentally generated for the first time. Such beams are a kind of new accelerating beams having five sampling points. Their optical topological structures and propagation characteristics are investigated subsequently. Moreover, we also find that the acceleration of quinary-cusp beams can be controlled by changing the Fourier transform lens with the different local lengths. Such research results are believed to pave the way toward future potential scientific applications of quinary-cusp beams. [ABSTRACT FROM AUTHOR]

Utilizing single-photon photoassociation, we have achieved ultracold rubidium molecules with a high number density that provides a new efficient approach toward molecular quantum degeneracy. A new detection mechanism for ultracold molecules utilizing inelastic atom-molecule collision is demonstrated. The resonant coupling effect on the formation of the X1Σ+ g ground state 85Rb2 allows for a sufficient number of more deeply bound ultracold molecules, which induced an additional trap loss and heating of the co-existing atoms owing to the inelastic atom-molecule collision. Therefore, after the photoassociation process, the ultracold molecules can be investigated using the absorption image of the ultracold rubidium atoms mixed with the molecules in a crossed optical dipole trap. The existence of the ultracold molecules was then verified, and the amount of accumulated molecules was measured. This method detects the final produced ultracold molecules, and hence is distinct from the conventional trap loss experiment, which is used to study the association resonance. It is composed of measurements of the time evolution of an atomic cloud and a decay model, by which the number density of the ultracold 85Rb2 molecules in the optical trap was estimated to be >5.2×1011 cm-3. [ABSTRACT FROM AUTHOR]

Localized optical Airy-Bessel configuration wave packets were first generated on the basis of a grating-telescope combination [Nat. Photon. 4 (2010) 103]. By studying the spatially induced group velocity dispersion effect of ultrashort pulsed Bessel beams during propagation, we find the universal physical foundation of generating Airy- Bessel wave packets (ABWs) in free space. The research results are expected to open up more common channels for generating stable linear localized ABWs. [ABSTRACT FROM AUTHOR]

Quantum discord, a measure of quantum correlation beyond entanglement, is initially defined as the discord between two classically equivalent while quantum discordant definitions of mutual information. In this paper, we report some new interpretations of discord which rely on the differences between measurement-induced effects on the local measured system and the whole system. Specifically, with proper quantitative definitions introduced in Buscemi et al (2008 Phys. Rev. Lett. 100 210504), we find that quantum discord can be interpreted as the differences of measurement-induced disturbance or information gain on the local measured system and on the whole system. Combined with previous similar results based on measurement-induced entanglement and decoherence, our results provide a unified view on quantum discord. [ABSTRACT FROM AUTHOR]

The mass neutrino interference phases along the null trajectory and the geodesic line in Kerr space-time are studied on the plane th = p/2. Because of the rotation object in Kerr space-time, a particle travelling along the radial geodesic must have a dragging effect produced by the angular momentum of the central object. We give the correction of the phase due to the rotation of the space-time. We find that the type-I interference phase along the geodesic remains the double of that along the null on the condition that the rotating quantity parameter a2 is preserved and the higher order terms are negligible (e.g. a4). In addition, we calculate the proper oscillation length in Kerr space-time. All of our results can return to those in Schwarzschild space-time as the rotating parameter a approaches zero. [ABSTRACT FROM AUTHOR]

Long-lived quantum speedup serves as a fundamental component for quantum algorithms. The quantum walk is identified as an ideal scheme to realize the long-lived quantum speedup. However, one finds that the duration of quantum speedup is too short in real systems to implement the quantum algorithms, for instance the speedup in the photosynthetic light-harvesting systems can last only dozens of femtoseconds. Here, we construct one plasmonic system with two-level molecules embodied in the hot spots of one-dimensional nanoparticle chains to realize the long-lived quantum speedup. The coherent and incoherent coupling parameters in the system are obtained by means of Green’s tensor technique. Our results reveal that the duration of quantum speedup in our scheme can exceed 500 fs under strong coherent coupling conditions. Moreover, our plasmonic system has far prospect in realizing high-dimensional quantum walk, which is very beneficial for quantum algorithms. [ABSTRACT FROM AUTHOR]

Solid refrigeration technology based on the elastocaloric effect has a great potential alternative to the conventional vapor compression cooling. Here we report the large elastocaloric effect in Ti–Ni (50 at%) shape memory alloy below its austenite finish temperature Af under different strain. Both Maxwell’s and Clausius–Clapeyron equations are used to estimate the entropy change. The strain-induced entropy change increases with raising the strain and gets a maximum value at a few kelvins below Af. The maximum entropy changes ΔSmax are −20.44 and −53.70 J/kg·K, respectively for 1% and 2% strain changes. Large entropy change may be obtained down to 20 K below Af. The temperature of the maximum entropy change remains unchanged before the plastic deformation appears but moves towards low temperature when the plastic deformation happens. [ABSTRACT FROM AUTHOR]

We investigate the spin–orbit coupling effect in a two-dimensional (2D) Wigner crystal. It is shown that sufficiently strong spin–orbit coupling and an appropriate sign of g-factor could transform the Wigner crystal to a topological phonon system. We demonstrate the existence of chiral phonon edge modes in finite size samples, as well as the robustness of the modes in the topological phase. We explore the possibility of realizing the topological phonon system in 2D Wigner crystals confined in semiconductor quantum wells/heterostructure. It is found that the spin–orbit coupling is too weak for driving a topological phase transition in these systems. It is argued that one may look for topological phonon systems in correlated Wigner crystals with emergent effective spin–orbit coupling. [ABSTRACT FROM AUTHOR]

We construct a density functional theory for two-dimensional electron (hole) gases subjected to both strong magnetic fields and external potentials. In particular, we are focused on regimes near even-denominator filling factors, in which the systems form composite fermion liquids. Our theory provides a systematic and rigorous approach to determine the properties of ground states in a fractional quantum Hall regime that is modified by artificial structures. We also propose a practical way to construct an approximated functional. [ABSTRACT FROM AUTHOR]

Airy beams and triple-cusp beams are two kinds of accelerating beams. The propagation characteristics and internal topological structures of accelerating Airy beams are well understood because of the developed mathematical theory about Airy function. However, limited information is available about the optical characteristics of accelerating triple-cusp beams. In this work, the relationship between Airy beams and triple-cusp beams is examined theoretically and experimentally. Results reveal some important optical characteristics of triple-cusp beams based on the optical characteristics of Airy beams. These findings are expected to provide a foundation for future applications of triple-cusp beams. [ABSTRACT FROM AUTHOR]

In this paper, we prove a stronger entanglement monogamy inequality in a 2[?]2[?]3 system's pure state |Ps[?]ABC. Specifically, we show that the linear entropy of rA, which is the entanglement between A and BC, is always larger than the sum of the square of concurrence between A and B and the square of concurrence of assistance between A and C. Our proof is based on direct generalizations of the qubit system's results. Our inequality is stronger than the known monogamy inequality of concurrence and shows that the entanglement of assistance always comes from the existing entanglement. However, our inequality also shows that unlike the three-qubit case, in higher dimensional systems the entanglement between A and BC cannot be completely transformed into bipartite entanglement with assistance. Through our proof, we also give some cases when the inequality reduces to an equality. [ABSTRACT FROM AUTHOR]

We analyze various possible superconducting pairing states and their relative stabilities in lightly doped graphene. It is shown that, when inter-sublattice electron-electron attractive interaction dominates and the Fermi level is close to the Dirac points, the system will favor intra-valley spin-triplet p + ip pairing state. Based on the novel pairing state, we further propose a scheme for doing topological quantum computation in graphene by engineering local strain fields and external magnetic fields. [ABSTRACT FROM AUTHOR]

The total reciprocal space magnetic flux threading through a closed Fermi surface is a topological invariant for a three-dimensional metal. For a Weyl metal, the invariant is nonzero for each of its Fermi surfaces. We show that such an invariant can be related to the magneto-valley-transport effect, in which an external magnetic field can induce a valley current. We further show that a strain field can drive an electric current, and that the effect is dictated by a second-class Chern invariant. These connections open the pathway to observe the hidden topological invariants in metallic systems. [ABSTRACT FROM AUTHOR]

We propose a general variational principle for mapping the interacting systems in continuous space to lattice models. Based on the principle, we derive a set of self-consistent nonlinear equations for the Wannier functions (or, equivalently for the Bloch functions). These equations show that the Wannier functions can be strongly influenced by the interaction and be significantly different from their non-interacting counterparts. The approach is demonstrated with interacting bosons in an optical lattice, and illustrated quantitatively by a simple model of interacting bosons in a double well potential. It is shown that the so-determined lattice model parameters can be significantly different from their non-interacting values. [ABSTRACT FROM AUTHOR]

It is important for a controlled release system to determine whether nanoparticles can penetrate cell membranes and deliver protein into the nuclear or cytosolic compartments of cells, and thus function as carriers. Here, we prepared different functionalized mesoporous magnetic hollow nanoparticles (MMHs) and chose bovine serum albumin (BSA) as a model protein to detect the intracellular trafficking of MMHs. The results showed that MMHs modified with amino groups (AMMHs) were efficient in protein loading and that the loading was dependent on the pH, temperature and ionic strength. Furthermore, we found that the AMMHs not only transported BSA into the cells but also released the BSA carried into the nuclear or cytosolic compartments of the cells. In addition, the nanoparticles were biocompatible, and the encapsulation of BSA in AMMHs did not affect their bioactivity. Taken together, AMMHs are excellent carriers for releasing protein into the cytosol and nucleus, and they have the potential to be used in a controlled release system. [ABSTRACT FROM AUTHOR]

An innovative drug delivery system based on magnetic and fluorescent multifunctional chitosan nanoparticles was developed, which combined magnetic targeting, fluorescent imaging and stimulus-responsive drug release properties into one drug delivery system. Water-soluble superparamagnetic Fe3O4 nanoparticles, CdTe quantum dots (QDs) and pharmaceutical drugs were simultaneously incorporated into chitosan nanoparticles; cross-linking the composite particles with glutaraldehyde tailored their size, morphology, surface properties and drug release behaviors. The system showed superparamagnetic and strong fluorescent properties, and was used as a controlled drug release vehicle, which showed pH-sensitive drug release over a long time. The composite magnetic and fluorescent chitosan nanoparticles are potential candidates as a smart drug delivery system. [ABSTRACT FROM AUTHOR]