We discuss the interaction of spatial solitary waves in nematic liquid crystals, termed nematicons, with localized inhomogeneities in the distribution of the optic axis. For beam waists small compared with the defect width, self-localization is preserved; in the opposite limit the spatial solitary waves undergo significant attenuation due to diffractive losses, to the extent that nematicons are essentially destroyed. Owing to their power-waist dependence spatial solitary waves interacting with defects in nematic liquid crystals are subject to an excitation-dependent transition from particlelike to wavelike behavior. In the latter regime their trajectory varies with input power, leading to novel approaches to the design and realization of all-optical circuits.

We use coherently rotating hydrogen molecules and demonstrate a continuous-wave optical modulator at a frequency of 17.6 THz that can modulate any laser within the optical region of the spectrum. The molecules are coherently excited using two intense laser beams spaced by the Raman transition frequency inside a high-finesse cavity.

We study the coherent transport of a single photon in a one-dimensional coupled-resonator array, nonlocally coupled to a two-level system. Since its inherent structure is a Mach-Zehnder interferometer, we explain the destructive interference phenomenon of the transmission spectra according to the effect of which-way detection. The quantum realization of the present model is a nanoelectromechanical resonator array with two nearest resonators coupled to a single spin via their attached magnetic tips. Its classical simulation is a waveguide of a coupled-defected cavity array with double couplings to a side-defected cavity.

We study discrete surface solitons in semi-infinite, one-dimensional, nonlinear (Kerr), quasiperiodic waveguide arrays of the Fibonacci and Aubry-André types, and explore different families of localized surface modes, as a function of optical power content (“nonlinearity”) and quasiperiodic strength (“disorder”). We find a strong asymmetry in the power content of the mode as a function of the propagation constant, between the cases of focusing and defocusing nonlinearity, in both models. We also examine the dynamical evolution of a completely localized initial excitation at the array surface. We find that, in general, for a given optical power, a smaller quasiperiodic strength is required to effect localization at the surface than in the bulk. Also, for fixed quasiperiodic strength, a smaller optical power is needed to localize the excitation at the edge than inside the bulk.

The choice of the wrong kernel for describing the cooperative effects in an ensemble of identical atoms, in most instances, leads to wrong predictions for the system's dynamics whether the system initially was excited weakly or nearly was inverted. In this Brief Report, using previously derived theoretical expressions, I compare the numerical values for the emission amplitude as a function of time for the complex exponential and the sine kernels for different-size spheres. The deviations found in the respective results show that, in general, the two kernels are not, as often claimed, up to a frequency shift in their spectra, interchangeable.

We analyze the security and feasibility of a protocol for quantum key distribution (QKD) in a context where only one of the two parties trusts his measurement apparatus. This scenario lies naturally between standard QKD, where both parties trust their measurement apparatuses, and device-independent QKD (DI-QKD), where neither do, and can be a natural assumption in some practical situations. We show that the requirements for obtaining secure keys are much easier to meet than for DI-QKD, which opens promising experimental opportunities. We clarify the link between the security of this one-sided DI-QKD scenario and the demonstration of quantum steering, in analogy to the link between DI-QKD and the violation of Bell inequalities.

We show that coherence between two excited rovibrational states belonging to the same molecular electronic configuration arises quite naturally due to their interaction with electromagnetic vacuum. For initial preparation of a molecule in the desired rovibrational states, we propose to employ the method of ultracold photoassociation. Spontaneous decay of the excited molecule then gives rise to vacuum-induced coherence between the excited ro-vibrational states. We demonstrate theoretically an interesting interplay of effects due to vacuum-induced coherence and photoassociation. We apply our theory to photoassociation of bosonic ytterbium (${}^{174}$Yb) atoms, which appear to be a promising system for exploring such interplay. The effects discussed here can be important for controlling decoherence and dissipation in molecular systems.

We study the phase diagram for spin-2 bosons loaded in a one-dimensional optical lattice. By using the non-Abelian density matrix renormalization group (DMRG) method we identify three possible phases: ferromagnetic, dimerized, and trimerized phases. We sketch the phase boundaries based on DMRG. We illustrate two methods for identifying the phases. The first method is based on the spin-spin correlation function, while in the second method one observes the excitation gap as a dimerization, or a trimerization superlattice is imposed. The advantage of the second method is that it also can be easily implemented in experiments. By using the scattering lengths in the literature we estimate that ${}^{83}$Rb, ${}^{23}$Na, and ${}^{87}$Rb can be ferromagnetic, dimerized, and trimerized, respectively.

We presented a general classification scheme for the tripartite $L\times N\times N$ entangled system under stochastic local operation and classical communication. The whole classification procedure consists of two correlated parts: the simultaneous similarity transformation of a commuting matrix pair into a canonical form and the study of internal symmetry of parameters in the canonical form. Based on this scheme, a concrete example of entanglement classification for a $3\times N\times N$ system is given.

We present a decoding procedure to transmit classical information in a quantum channel which, saturating asymptotically the Holevo bound, achieves the optimal rate of the communication line. In contrast to previous proposals, it is based on performing a sequence of projective yes-no measurements which in $N$ steps determines which codeword was sent by the sender ($N$ being the number of the codewords). Our analysis shows that, as long as $N$ is below the limit imposed by the Holevo bound, the error probability can be sent to zero asymptotically in the length of the codewords.

The accuracy of the Faddeev random phase approximation (FRPA) method is tested by evaluating total and ionization energies in the basis-set limit. A set of light atoms up to Ar is considered. Comparisons are made with the results of coupled-cluster singles and doubles (CCSD), with third-order algebraic diagrammatic construction [ADC(3)], and with the experiment. It is seen that even for two-electron systems, He and Be${}^{2+}$, the inclusion of RPA effects leads to satisfactory results, and therefore it does not overcorrelate the ground state. The FRPA becomes progressively better for larger atomic numbers, where it gives $\approx$5 mH more correlation energy, and it shifts ionization potentials by 2–10 mH with respect to the similar ADC(3) method. The ionization potentials from FRPA tend to reduce the discrepancies with the experiment.

We perform laser spectroscopy of Yb${}^{+}$ ions on the 4$f^{14}6s{}^2{S}_{1/2}$-$4f^{13}5d6s$ ${}^{3}D{[3/2]}_{1/2}$ transition at 297 nm. The frequency measurements for ${}^{170}$Yb${}^{+}$, ${}^{172}$Yb${}^{+}$, ${}^{174}$Yb${}^{+}$, and ${}^{176}$Yb${}^{+}$ reveal the specific mass shift as well as the field shifts. In addition, we demonstrate laser cooling of Yb${}^{+}$ ions using this transition and show that light at 297 nm can be used as the second step in the photoionization of neutral Yb atoms.

A large amount of work has been performed on positron and positronium (Ps) binding to atoms. Positron binding was treated in our last paper [Phys. Rev. A 83, 032504 (2011)], of which the present paper is a continuation. For Ps binding, 12 atoms have been found to bind with Ps, and 2 atoms have been found not to bind with Ps. We fit the known binding energies to a simple expression involving a few common physical properties and then use it to predict the Ps-binding energies of the other atoms. The model and results appear to be reliable.

Electrostatic patch potentials give rise to forces between neutral conductors at distances in the micrometer range and must be accounted for in the analysis of Casimir force experiments. In this paper we develop a quasilocal model for describing random potentials on metallic surfaces. In contrast to some previously published results, we find that patches may provide a significant contribution to the measured signal and thus may be a more important systematic effect than was previously anticipated. Additionally, patches may render the experimental data at distances below 1 $\mu$m compatible with theoretical predictions based on the Drude model.

We have investigated photoassociative formation of RbCs molecules in the ${\left(2\right)}^3\Pi$ excited state correlated to $v=8$, $\left(5\right)0^{+}$ vibrational level in detail. The metastable ground-state RbCs molecules formed by spontaneous decay are ionized by pulsed dye laser through resonance-enhanced two-photon ionization. A rate equation of the photoionization process is introduced to explain the dependence of RbCs${}^{+}$ molecular ion intensity on the ionization laser intensity. The saturation effect of molecular ion intensity appears as the photoassociation laser intensity increases. The rotational constant and centrifugal distortion constant are derived to be 0.01304 cm${}^{-1}$ and 0.000015 cm${}^{-1}$ from the photoassociation spectrum with a high sensitivity, respectively. The measured electric dipole moment of the observed $\left(2\right){}^3\Pi$ state RbCs molecules is 4.7(6) D by Stark effect in static electric field.

We study the elastic scattering of a muon neutrino by an electron in the presence of a linearly polarized laser field in the frame of the standard model, and multiphoton processes are observed. The distributions of a multiphoton energy transfer (MPET) spectrum are greatly affected even by the laser fields in a moderate intensity range, while the total differential cross section can be largely changed by several orders of magnitude only in extreme strong laser fields with ultrarelativistic electrons. The method of stationary phase approximation is used for analyzing and elucidating the phenomena of cutoff, oscillation, and shift found in a MPET spectrum. We also analyze the reason giving rise to “dark windows” and geometric asymmetry initially noted in the potential scattering. By comparing the results we reach the conclusion that these effects are closely related to the order and arguments of generalized Bessel functions.

We theoretically investigate a two-photon process via molecular internal conversion, driven by correlated photons with time delay. As an example, a molecular system approximated by Morse oscillators is used in order to evaluate the efficiency of the process, in terms of how the efficiency changes with the nonadiabatic coupling rate of vibronic states. We show that an efficient two-photon process requires two different correlated photon pairs with positive and negative energy correlations, depending on the value of the nonadiabatic coupling rate.