Anomalous motional heating is a major obstacle to scalable quantum information processing with trapped ions. Although the source of this heating is not yet understood, several previous studies suggest that noise due to surface contaminants is the limiting heating mechanism in some instances. We demo…

[Phys. Rev. A 92, 020302(R)] Published Fri Aug 28, 2015

]]>The puzzling properties of quantum mechanics, i.e., wave-particle duality, entanglement, and superposition, have been dissected experimentally over the past decades. However, hidden-variable (HV) models based on three classical assumptions of wave-particle objectivity, determinism, and independence …

[Phys. Rev. A 92, 022126] Published Fri Aug 28, 2015

]]>We show how to construct loss-tolerant linear steering inequalities using a generic set of von Neumann measurements that are violated by $d$-dimensional states, and that rely only upon a simple property of the set of measurements used (the maximal overlap between measurement directions). Using these i…

[Phys. Rev. A 92, 022354] Published Fri Aug 28, 2015

]]>The no-signaling principle arising from the finite speed of light is considered, and it is shown how this simple principle directly leads to tight bounds for various quantum communication tasks.

[Phys. Rev. A 92, 022355] Published Fri Aug 28, 2015

]]>We suggest a way to quantify a type of macroscopic entanglement via distillation of Greenberger-Horne-Zeilinger states by local operations and classical communication. We analyze how this relates to an existing measure of quantum macroscopicity based on the quantum Fisher information in several exam…

[Phys. Rev. A 92, 022356] Published Fri Aug 28, 2015

]]>Quantum interference between energetically close states is theoretically investigated, with the state structure being observed via laser spectroscopy. In this work, we focus on hyperfine states of selected hydrogenic muonic isotopes, and on how quantum interference affects the measured Lamb shift. T…

[Phys. Rev. A 92, 022514] Published Fri Aug 28, 2015

]]>We investigate the four-body Coulomb process of low-energy elastic positronium-hydrogen (Ps-H) scattering below the Ps($n=2$) excitation threshold using scattering wave functions that include Hylleraas-type correlation terms. Using the complex Kohn variational method, we compute phase shifts through t…

[Phys. Rev. A 92, 022713] Published Fri Aug 28, 2015

]]>We present a numerical study for optimization of ultrabroad supercontinuum spectrum by controlling the waveforms of laser fields, with the ultimate goal to generate isolated ultrashort attosecond pulses. Specifically, we extend a derivative-free nonconvex optimization algorithm for maximization of t…

[Phys. Rev. A 92, 023423] Published Fri Aug 28, 2015

]]>We present ground-state calculations for low-density Fermi gases described by two model interactions, an attractive square-well potential and a Lennard-Jones potential, of varying strength. We use the optimized Fermi-hypernetted chain integral equation method, which has been proved to provide, in th…

[Phys. Rev. A 92, 023640] Published Fri Aug 28, 2015

]]>We introduce a theoretical approach to determine the spin structure of harmonically trapped atoms with two-body zero-range interactions subject to an equal mixture of Rashba and Dresselhaus spin-orbit coupling created through Raman coupling of atomic hyperfine states. The spin structure of bosonic a…

[Phys. Rev. A 92, 023641] Published Fri Aug 28, 2015

]]>A moving boundary separating two otherwise homogeneous regions of a dielectric is known to emit radiation from the quantum vacuum. An analytical framework based on the Hopfield model, describing a moving refractive-index step in $1+1$ dimensions for realistic dispersive media has been developed by S. …

[Phys. Rev. A 92, 023851] Published Fri Aug 28, 2015

]]>We use a microscopic model, the mirror-oscillator-field (MOF) model proposed by C. R. Galley, R. O. Behunin, and B. L. Hu [Phys. Rev. A **87**, 043832 (2013)], to describe the quantum entanglement between a mirror's center-of-mass (c.m.) motion and a field. In contrast with the conventional approach whe…

[Phys. Rev. A 92, 023852] Published Fri Aug 28, 2015

]]>Exact Hermite-Gaussian solutions to the Klein-Gordon equation for particle beams are obtained here that depend on the 4-position of the beam waist. These are Bateman-Hillion solutions that are shown to include Gouy phase and preserve their forms under Lorentz transformations. As the wave function co…

[Phys. Rev. A 92, 023853] Published Fri Aug 28, 2015

]]>We report an experimental comparison of critical intensities of nonlinear self-focusing in air with conventional focusing and spatiotemporal focusing schemes. Our results show that the conventional focusing with the focal lens completely filled with the incident beam allows for a higher peak intensi…

[Phys. Rev. A 92, 023854] Published Fri Aug 28, 2015

]]>We investigate the properties of the optical output fields from a cavity optomechanical system, where the cavity is optically driven by a strong coupling field and a weak probe field and the mechanical resonator is driven by a coherent mechanical pump. When the frequency of the mechanical pump match…

[Phys. Rev. A 92, 023855] Published Fri Aug 28, 2015

]]>The universal three-fermion bound states arising at a p-wave Feshbach resonance when the three particles are confined in two dimensions are studied, and a universal effective potential that is responsible for the scaling of these states is identified.

[Phys. Rev. A 92, 020504(R)] Published Thu Aug 27, 2015

]]>Based on the theory of quantum mechanics, intrinsic randomness in measurement distinguishes quantum effects from classical ones. From the perspective of states, this quantum feature can be summarized as coherence or superposition in a specific (classical) computational basis. Recently, by regarding …

[Phys. Rev. A 92, 022124] Published Thu Aug 27, 2015

]]>We study a simple open quantum system with a $\mathcal{PT}$-symmetric defect potential as a prototype in order to illustrate a number of general features of $\mathcal{PT}$-symmetric open quantum systems; however, the potential itself could be mimicked by a number of $\mathcal{PT}$ systems that have been experimentally studied quite re…

[Phys. Rev. A 92, 022125] Published Thu Aug 27, 2015

]]>A general quantum search algorithm aims to evolve a quantum system from a known source state $|s\rangle $ to an unknown target state $|t\rangle $. It uses a diffusion operator ${D}_{s}$ that has the source state as one of its eigenstates and ${I}_{t}$, where ${I}_{\psi}$ denotes the selective phase inversion of the $|\psi \rangle $ state. It evolves $|s\rangle $…

[Phys. Rev. A 92, 022353] Published Thu Aug 27, 2015

]]>Potential-functional theory is an intriguing alternative to density-functional theory for solving electronic-structure problems. We derive and solve equations using interacting potential functionals. A semiclassical approximation to exchange in one dimension with hard-wall boundary conditions is fou…

[Phys. Rev. A 92, 022513] Published Thu Aug 27, 2015

]]>The dynamic electric dipole polarizability function for the magnesium atom is formed by assembling the atomic electric dipole oscillator strength distribution from combinations of theoretical and experimental data for resonance oscillator strengths and for photoionization cross sections of valence a…

[Phys. Rev. A 92, 022712] Published Thu Aug 27, 2015

]]>We consider the recollision process occurring during the ionization of a neutral atom or molecule by a very strong linearly polarized near-infrared laser field. We find that Coulomb focusing persists even when the Coulomb field of the ion is barely noticeable compared with the laser field. We focus …

[Phys. Rev. A 92, 023422] Published Thu Aug 27, 2015

]]>We conduct a detailed analysis of a phase estimation experiment with a Bose-Einstein condensate in a double potential well. Our goal is to confront the theoretical considerations with the conditions of a real experiment. We present a typical experimental procedure and the theoretical model. We simul…

[Phys. Rev. A 92, 023639] Published Thu Aug 27, 2015

]]>We study the directional properties of a radiation field emitted by a geometrically small system composed of two identical two-level emitters located at short distances and driven by an optical vortex beam, a Laguerre-Gaussian beam which possesses a structured phase and amplitude. We find that the s…

[Phys. Rev. A 92, 023850] Published Thu Aug 27, 2015

]]>Complex quantum systems consisting of large numbers of strongly coupled states exhibit characteristic level repulsion, leading to a non-Poisson spacing distribution which can be described by random matrix theory. Scattering resonances observed in ultracold atomic and molecular systems exhibit simila…

[Phys. Rev. A 92, 020702(R)] Published Wed Aug 26, 2015

]]>Optomechanics is currently believed to provide a promising route towards the achievement of genuine quantum effects at the large, massive-system scale. By using a recently proposed figure of merit that is well suited to address continuous-variable systems, in this paper we analyze the requirements n…

[Phys. Rev. A 92, 022123] Published Wed Aug 26, 2015

]]>A universal deterministic noiseless quantum amplifier has been shown to be impossible. However, probabilistic noiseless amplification of a certain set of states is physically permissible. Regarding quantum state amplification as quantum state transformation, we show that deterministic noiseless ampl…

[Phys. Rev. A 92, 022352] Published Wed Aug 26, 2015

]]>We analyze the momentum distribution function and its artificial-gauge-field dependence for the Mott insulator phases of the Hofstadter-Bose-Hubbard model. By benchmarking the results of the random-phase approximation approach against those of the strong-coupling expansion for the Landau and symmetr…

[Phys. Rev. A 92, 023636] Published Wed Aug 26, 2015

]]>We study energy transport in a chain of quantum harmonic and anharmonic oscillators where the anharmonicity is induced by interaction between local vibrational states of the chain. Using adiabatic elimination and numerical simulations with matrix product states, we show how strong interactions signi…

[Phys. Rev. A 92, 023637] Published Wed Aug 26, 2015

]]>Beliaev damping in a superfluid is the decay of a collective excitation into two lower-frequency collective excitations; it represents the only decay mode for a bosonic collective excitation in a superfluid at $T=0$. The standard treatment for this decay assumes a linear spectrum, which in turn implie…

[Phys. Rev. A 92, 023638] Published Wed Aug 26, 2015

]]>Increasing the electron density of collisionally pumped plasma-based soft-x-ray lasers offers promising opportunities to deliver ultrashort pulses. However, strong nonlinear effects, such as overionization-induced refraction and self-focusing, hinder the propagation of the laser beam and thus the ge…

[Phys. Rev. A 92, 023848] Published Wed Aug 26, 2015

]]>We study both theoretically and experimentally the effects of introducing deliberate disorder in a slow-light photonic crystal waveguide on the photon density of states. We introduce a theoretical model that includes both deliberate disorder through statistically moving the hole centers in the photo…

[Phys. Rev. A 92, 023849] Published Wed Aug 26, 2015

]]>We have measured the hyperfine structure and isotope shifts of the 402.0- and 399.6-nm resonance lines in ${}^{229}\mathrm{Th}^{+}$. These transitions could provide pathways towards the excitation of the ${}^{229}\mathrm{Th}$ low-energy isomeric nuclear state. An unexpected negative isotope shift relative to ${}^{232}\mathrm{Th}^{+}$ is observed for th…

[Phys. Rev. A 92, 020503(R)] Published Tue Aug 25, 2015

]]>Anisotropy of the dipolar interaction between Rydberg atoms near a resonance is experimentally mapped out and controllability is demonstrated, opening up many possibilities in the implementation of quantum information protocols and the quantum simulation of many-body spin systems.

[Phys. Rev. A 92, 020701(R)] Published Tue Aug 25, 2015

]]>Quantum electrodynamics under conditions of distinguishability of interacting matter entities, and of controlled actions and back-actions between them, is considered. Such “mesoscopic quantum electrodynamics” is shown to share its dynamical structure with the classical stochastic electrodynamics. In…

[Phys. Rev. A 92, 022122] Published Tue Aug 25, 2015

]]>Resonant charge transfer (RCT) between negative ions and a metallic nanosystem was investigated by means of a high-performance *ab initio* three-dimensional (3D) numerical solver. During RCT, an electron was shown to occupy succesively nanosystem eigenstates along the $z,\rho $, and $\phi $ coordinates. Electron…

[Phys. Rev. A 92, 022710] Published Tue Aug 25, 2015

]]>A theoretical method for treating collisions in the presence of multiple potentials is developed by employing the Schwinger variational principle. The current treatment agrees with the local (regularized) frame transformation theory and extends its capabilities. Specifically, the Schwinger variation…

[Phys. Rev. A 92, 022711] Published Tue Aug 25, 2015

]]>We study theoretically many-body equilibrium magnetic phases and corresponding thermodynamic characteristics of ultracold three-component fermionic mixtures in optical lattices described by the SU(3)-symmetric single-band Hubbard model. Our analysis is based on the generalization of the exact diagon…

[Phys. Rev. A 92, 023633] Published Tue Aug 25, 2015

]]>We study a system of few fermions in a one-dimensional harmonic trap and focus on the case of dipolar majority particles in contact with a single impurity. The impurity is used both for quenching the system and for tracking the system evolution after the quench. Employing exact diagonalization, we i…

[Phys. Rev. A 92, 023634] Published Tue Aug 25, 2015

]]>Scaling in the dynamical properties of complex many-body systems has been of strong interest since turbulence phenomena became the subject of systematic mathematical studies. In this article, dynamical critical phenomena far from equilibrium are investigated with functional renormalization-group equ…

[Phys. Rev. A 92, 023635] Published Tue Aug 25, 2015

]]>Information of plasmonic modes in the Buckminster fullerene C${}_{60}$ is extracted from $a\phantom{\rule{0}{0ex}}b$ $i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}o$ time-dependent density-functional-theory calculations with excellent agreement with experimental results, which underlines the importance of multipole (high angular momentum) contributions to the collective excitations well beyond what has been understood by previous models.

[Phys. Rev. A 92, 021403(R)] Published Mon Aug 24, 2015

]]>Optical frequency transfer with record-high accuracy ($1\times {10}^{-20}$ uncertainty) is realized over a 1400km loop of underground fiber between Braunschweig and Strasbourg, which enables reliable synchronization of state-of-the-art atomic clocks that are accurate enough to detect changes in the fabric of space-time.

[Phys. Rev. A 92, 021801(R)] Published Mon Aug 24, 2015

]]>Solving realistic quantum systems coupled to an environment is a challenging task. Here we develop a hierarchical functional derivative (HFD) approach for efficiently solving the non-Markovian quantum trajectories of an open quantum system embedded in a bosonic bath. An explicit expression for arbit…

[Phys. Rev. A 92, 022119] Published Mon Aug 24, 2015

]]>In this paper, we characterize the *global* multipartite nonlocality in one-dimensional infinite-size spin-1/2 chains. For this purpose, we calculate the multipartite nonlocality of $n$-site subchains, and take the large-$n$ limit. As $n$ increases from 2 to 100, we find that the average revenue and the mar…

[Phys. Rev. A 92, 022120] Published Mon Aug 24, 2015

]]>It remains a challenge for theory to simulate nonperturbative and non-Markovian quantum dissipative dynamics at low temperatures. In this study we suggest a Hermitian non-Markovian stochastic master equation suitable for dissipative dynamics at arbitrary temperatures. The memory effect of the bath i…

[Phys. Rev. A 92, 022121] Published Mon Aug 24, 2015

]]>The analysis of a physical problem simplifies considerably when one uses a suitable coordinate system. We apply this approach to the discrete-time quantum walks with coins given by $2j+1$-dimensional Wigner rotation matrices (Wigner walks), a model which was introduced in Miyazaki *et al.* [Phys. Rev. A…

[Phys. Rev. A 92, 022347] Published Mon Aug 24, 2015

]]>The simulated annealing algorithm, a method commonly used to calculate properties of condensed-matter systems, is used to calculate entanglement of formation for higher-dimensional mixed states. The method relies on representing a mixed state as a pure state in an enlarged Hilbert space, and on the …

[Phys. Rev. A 92, 022348] Published Mon Aug 24, 2015

]]>The recently developed formalism of Markovian master equations for quantum open systems with external periodic driving is applied to the theory of dynamical decoupling by periodic control. This new approach provides a more detailed quantitative picture of this phenomenon applicable both to tradition…

[Phys. Rev. A 92, 022349] Published Mon Aug 24, 2015

]]>Spin-chain models have been widely studied in terms of quantum information processes, for instance for the faithful transmission of quantum states. Here, we investigate the limitations of mapping this process to an equivalent one through a bosonic chain. In particular, we keep in mind experimental i…

[Phys. Rev. A 92, 022350] Published Mon Aug 24, 2015

]]>We consider networks featuring preparation, transformation, and measurement devices, in which devices exchange communication via mediating physical systems. We investigate the problem of testing the dimension of the mediating systems in the device-independent scenario, that is, based on observable d…

[Phys. Rev. A 92, 022351] Published Mon Aug 24, 2015

]]>We present extreme ultraviolet and visible spectra of promethiumlike tungsten and gold obtained with an electron beam ion trap. Although the contributions from a few charge states are involved in the spectra, the charge state of the ion assigned to the observed lines is definitely identified by the …

[Phys. Rev. A 92, 022510] Published Mon Aug 24, 2015

]]>A counterintuitive scheme to produce ultracold hydrogen via fragmentation of laser cooled diatomic hydrides is presented where the final atomic H temperature is inversely proportional to the mass of the molecular parent. In addition, the critical density for formation of a Bose-Einstein condensate (…

[Phys. Rev. A 92, 022511] Published Mon Aug 24, 2015

]]>We present a linear-scaling approach based on semidefinite programs (SDPs) to compute the density matrix for effective one-electron theories. Traditional methods constrain the density matrix to represent a Slater determinant and hence rely on parameterization or purification. We eliminate the need f…

[Phys. Rev. A 92, 022512] Published Mon Aug 24, 2015

]]>Stopping powers of antiprotons in H, He, Ne, Ar, Kr, and Xe targets are calculated using a semiclassical time-dependent convergent close-coupling method. The helium target is treated using both frozen-core and multiconfiguration approximations. The electron-electron correlation of the target is full…

[Phys. Rev. A 92, 022707] Published Mon Aug 24, 2015

]]>We explore the magnetic Feshbach spectra of ultracold ground-state Li+Er systems. Our calculations predict many tunable resonances at fields below 1000 G that could be stably tuned in ultracold experiments. We show that Li+Er spectra are much less congested than those of systems involving heavier hi…

[Phys. Rev. A 92, 022708] Published Mon Aug 24, 2015

]]>Optical Feshbach resonances (OFRs) have generated significant experimental interest in recent years. These resonances are promising for many-body physics experiments, yet the practical application of OFRs has been limited. The theory of OFRs has been based on an approximate model that fails in impor…

[Phys. Rev. A 92, 022709] Published Mon Aug 24, 2015

]]>We perform a systematic analysis of quantum interference in nonsequential double ionization focusing on the recollision excitation with subsequent ionization (RESI) mechanism, employing the strong-field approximation (SFA). We find that interference has a major influence on the shape, localization, …

[Phys. Rev. A 92, 023421] Published Mon Aug 24, 2015

]]>We investigate the ground-state properties of Bose-Bose mixtures with Rashba-type spin-orbit (SO) coupling in a square lattice. The system displays rich physics from the deep Mott insulator (MI) all the way to the superfluid (SF) regime. In the deep MI regime, exotic spin-ordered phases arise due to…

[Phys. Rev. A 92, 023630] Published Mon Aug 24, 2015

]]>The relationship between natural orbitals, one-body coherences, and two-body correlations is explored for bosonic many-body systems of definite parity with two occupied single-particle states. We show that the strength of local two-body correlations at the parity-symmetry center characterizes the nu…

[Phys. Rev. A 92, 023631] Published Mon Aug 24, 2015

]]>We study an extended Bose-Hubbard model with next-nearest-neighbor (NNN) hopping in a shaken optical lattice. We show how mean-field phase diagram evolves with the change of NNN hopping amplitude ${t}_{2}$, which can be easily tuned via shaking amplitude. As ${t}_{2}$ increases, a ${Z}_{2}$-symmetry-breaking superfluid $\dots $

[Phys. Rev. A 92, 023632] Published Mon Aug 24, 2015

]]>We theoretically analyze linear and nonlinear coherent propagation of linearly polarized, plane-wave, resonant single-cycle terahertz pulses through spatially extended rigid-rotor molecular media. Our model incorporates mixed state medium preparation, nonperturbative nonlinearities, saturation, cohe…

[Phys. Rev. A 92, 023843] Published Mon Aug 24, 2015

]]>Radiation torques exerted by focused Laguerre-Gaussian beams on a microsphere are investigated with the generalized Lorenz-Mie theory. It is shown that the spin and orbital torques, in particular, those exerted by circularly polarized beams, can be far larger than the net torque in magnitude, which …

[Phys. Rev. A 92, 023844] Published Mon Aug 24, 2015

]]>Motivated by a recent experiment with optical lattices that has realized a ladder geometry with an effective magnetic field [Atala *et al.*, Nat. Phys. **10**, 588 (2014)], we study the dynamics of bosons on a tight-binding two-leg ladder with complex hopping amplitudes. This system displays a quantum ph…

[Phys. Rev. A 92, 023845] Published Mon Aug 24, 2015

]]>We explain the probe field transmission spectrum under the influence of a strong pump field in a hybrid optomechanical system, composed of an optical cavity, a mechanical resonator, and a two-level atom. We show fast (superluminal) and slow (subluminal) light effects of the transmitted probe field i…

[Phys. Rev. A 92, 023846] Published Mon Aug 24, 2015

]]>The quantum correlation of light and atomic collective excitation can be used to compose an SU(1,1)-type hybrid light-atom interferometer, where one arm in the optical SU(1,1) interferometer is replaced by the atomic collective excitation. The phase-sensing probes include not only the photon field b…

[Phys. Rev. A 92, 023847] Published Mon Aug 24, 2015

]]>We discuss the deterministic Gaussian entangling procedure between continuous variables of two directly noninteracting oscillators. The oscillators can only couple to the same mediating oscillator, which is initially at arbitrary noisy state and can be lost after the procedure. Unitary idealization …

[Phys. Rev. A 92, 022346] Published Fri Aug 21, 2015

]]>We propose a dark-state cooling method of trapped ion systems in the Lamb-Dicke limit. By microwave dressing the ion, we can obtain two electromagnetically induced transparency structures. The heating effects caused by the carrier and the blue sideband transition vanish due to electromagnetically in…

[Phys. Rev. A 92, 023420] Published Fri Aug 21, 2015

]]>We study propagation of $\gamma $ radiation from a Mössbauer radioactive source through a vibrating recoilless resonant absorber and find the optimal conditions to produce a periodic train of $\gamma $-ray pulses with maximum peak intensity, several times higher than the intensity from the source, and minimum durat…

[Phys. Rev. A 92, 023841] Published Fri Aug 21, 2015

]]>We investigate theoretically the quantum Rabi model in the large-detuning regime. When the frequency of the cavity field is near one-third of the atomic transition frequency, we show that there exists a resonant three-photon coupling via intermediate states connected by counter-rotating processes. W…

[Phys. Rev. A 92, 023842] Published Fri Aug 21, 2015

]]>We investigate the weak measurement experiment demonstrated by Ritchie *et al.* [N. W. M. Ritchie, J. G. Story, and R. G. Hulet, Phys. Rev. Lett. **66**, 1107 (1991)] from the viewpoint of the statistical hypothesis testing for the weak-value amplification proposed by Susa and Tanaka [Y. Susa and S. Tanak…

[Phys. Rev. A 92, 022118] Published Thu Aug 20, 2015

]]>“Contagious quantum germs”, a type of error in quantum computing that can continue to cause error for every infected qubit with arbitrary quantum entanglement and correlation, is proposed, analyzed, and with a “cure” found to reduce the error to a milder, quasi-independent error by teleportation.

[Phys. Rev. A 92, 022345] Published Thu Aug 20, 2015

]]>A first-principles, QED derivation reveals a different type of line broadening of atomic levels induced by blackbody radiation, which is expected to help in the understanding of the evolution of the early universe when hydrogen atoms were first formed.

[Phys. Rev. A 92, 022508] Published Thu Aug 20, 2015

]]>We have measured the $3{s}_{1/2}\text{\u2212}3{p}_{3/2}$ transition in sodiumlike ${\mathrm{Eu}}^{52+}$ situated at 41.232 Å with an uncertainty of 73 ppm. Our measurement extends previous high-precision measurements into the $56<Z<78$ range of atomic numbers. We also present measurements of $3{s}_{1/2}\text{\u2212}3{p}_{3/2}$ and $3{p}_{1/2}\text{\u2212}3{d}_{3/2}$ transitions in …

[Phys. Rev. A 92, 022509] Published Thu Aug 20, 2015

]]>A fully quantum procedure, based on the numerical solution of the time-dependent Schrödinger equation (TDSE) with two spatial dimensions for every electron, is developed to study the attosecond double-ionization (DI) dynamics from aligned ${\mathrm{H}}_{2}$ molecules in strong laser fields. Our simulations are able…

[Phys. Rev. A 92, 023418] Published Thu Aug 20, 2015

]]>We present calculations of the Zeeman effect of narrow photoassociation lines of ${}^{40}\mathrm{Ca}$ near the ${}^{3}P_{1}+{}^{1}S_{0}$ asymptote. Using a coupled-channel model we find a nonlinear Zeeman effect that even at low fields of a few mT amounts to several kHz. With this model we analyze previous measurements and give corr…

[Phys. Rev. A 92, 023419] Published Thu Aug 20, 2015

]]>When vortices are displaced in Bose-Einstein condensates (BECs), the Magnus force gives the system a momentum transverse in the direction to the displacement. We show that BECs in long channels with vortices exhibit a quantization of the current response with respect to the spatial vortex distributi…

[Phys. Rev. A 92, 023629] Published Thu Aug 20, 2015

]]>We observe experimentally the spectral signature of the collision between a soliton and the dispersive wave initially emitted from the soliton itself. This collision, interpreted in terms of an optical event horizon, is controlled by the use of an axially varying fiber which allows us to shape both …

[Phys. Rev. A 92, 023837] Published Thu Aug 20, 2015

]]>The photon blockade based on weak nonlinearities is called the unconventional photon blockade. The study of the unconventional photon blockade in recent decades has mainly focused on the ${\chi}^{\left(3\right)}$ Kerr nonlinearity. In this paper, we study the photon blockade in two weakly coupled nonlinear cavities via ${\dots}^{}$

[Phys. Rev. A 92, 023838] Published Thu Aug 20, 2015

]]>We show that confluent Darboux-Crum transformations with emergent Jordan states are an effective tool for the design of optical systems governed by the Helmholtz equation under the paraxial approximation. The construction of generic, asymptotically real and periodic, $PT$-symmetric systems with local …

[Phys. Rev. A 92, 023839] Published Thu Aug 20, 2015

]]>We investigate the spatiotemporal evolution of a Gaussian probe pulse propagating through a four-level $N$-type atomic medium. At two-photon resonance of probe and control fields, weaker probe pulses may propagate through the medium with low absorption and pulse shape distortion. In contrast, we find …

[Phys. Rev. A 92, 023840] Published Thu Aug 20, 2015

]]>We develop a numerical procedure to efficiently model the nonequilibrium steady state of one-dimensional arrays of open quantum systems based on a matrix-product operator ansatz for the density matrix. The procedure searches for the null eigenvalue of the Liouvillian superoperator by sweeping along …

[Phys. Rev. A 92, 022116] Published Wed Aug 19, 2015

]]>Postselection is the process of discarding outcomes from statistical trials that are not the event one desires. Postselection can be useful in many applications where the cost of getting the wrong event is implicitly high. However, unless this cost is specified exactly, one might conclude that disca…

[Phys. Rev. A 92, 022117] Published Wed Aug 19, 2015

]]>We propose and experimentally demonstrate a scheme for the implementation of a maximally entangling quantum controlled-$Z$ gate between two weakly interacting systems. We conditionally enhance the interqubit coupling by quantum interference. Both before and after the interqubit interaction, one of the…

[Phys. Rev. A 92, 022341] Published Wed Aug 19, 2015

]]>We study the generation of entangled light in planar semiconductor microcavities. The focus is on a particular pump configuration where the dissipative internal polariton dynamics leads to the emission of entangled light in a $W$ state. Our study is based on the nonlinear equations of motion for the p…

[Phys. Rev. A 92, 022342] Published Wed Aug 19, 2015

]]>We have studied here the evolution of entanglement towards criticality in the $\mathit{XY}$ model when quantum phase transition (QPT) is induced by a quench. To this end, we have utilized the relation of the Berry phase acquired by a spin state when it traverses a closed path at criticality with the concurrenc…

[Phys. Rev. A 92, 022343] Published Wed Aug 19, 2015

]]>We propose a physical implementation of time and spatial parity transformations, as well as Galilean boosts, in a trapped-ion quantum simulator. By embedding the simulated model into an enlarged simulating Hilbert space, these fundamental symmetry operations can be fully realized and measured with i…

[Phys. Rev. A 92, 022344] Published Wed Aug 19, 2015

]]>Fluorescence yields (FYs) for the Ge $L$ shell were determined by a theoretical and two experimental groups within the framework of the International Initiative on X-Ray Fundamental Parameters Collaboration. Calculations were performed using the Dirac-Fock method, including relativistic and QED correc…

[Phys. Rev. A 92, 022507] Published Wed Aug 19, 2015

]]>We have experimentally and theoretically studied the fragmentation dynamics of argon trimer $\left(\mathrm{A}{\mathrm{r}}_{3}\right)$ in intense laser fields. By coincidently measuring the momentum vectors, we obtained the emission geometry of the three fragmental ions produced in the three-body fragmentation process. In addition to t…

[Phys. Rev. A 92, 023417] Published Wed Aug 19, 2015

]]>Diffraction phenomena usually can be formulated in terms of a potential that induces the redistribution of a wave's momentum. Using an atomic Bose-Einstein condensate coupled to the orbitals of a state-selective optical lattice, we investigate a hitherto unexplored nonadiabatic regime of diffraction…

[Phys. Rev. A 92, 023628] Published Wed Aug 19, 2015

]]>We investigate multiple Fano, comblike scattering resonances in single-layered, concentric core-shell nanoparticles composed of magnetic materials. Using the Lorenz-Mie theory, we derive, in the long-wavelength limit, an analytical condition for the occurrence of comblike resonances in the single sc…

[Phys. Rev. A 92, 023835] Published Wed Aug 19, 2015

]]>We propose a method to transform a single-photon field into bunches of pulses with controllable timing and number of pulses in a bunch. The method is based on transmission of a photon through an optically thick single-line absorber vibrated with a frequency appreciably exceeding the width of the abs…

[Phys. Rev. A 92, 023836] Published Wed Aug 19, 2015

]]>Side-channel attacks currently constitute the main challenge for quantum key distribution (QKD) to bridge theory with practice. So far two main approaches have been introduced to address this problem, (full) device-independent QKD and measurement-device-independent QKD. Here we present a third solut…

[Phys. Rev. A 92, 022337] Published Tue Aug 18, 2015

]]>We identify a key difference between quantum search by discrete- and continuous-time quantum walks: a discrete-time walk typically performs one walk step per oracle query, whereas a continuous-time walk can effectively perform multiple walk steps per query while only counting query time. As a result…

[Phys. Rev. A 92, 022338] Published Tue Aug 18, 2015

]]>We describe a criterion for the detection of entanglement between two multiboson systems. The criterion is based on calculating correlations of Gell-Mann matrices with a fixed boson number on each subsystem. This applies naturally to systems such as two entangled spinor Bose-Einstein condensates. We…

[Phys. Rev. A 92, 022339] Published Tue Aug 18, 2015

]]>The impact of control sequences on the environmental coupling of a quantum system can be described in terms of a filter. Here we analyze how the coherent evolution of two interacting spins subject to periodic control pulses, using the example of a nitrogen vacancy center coupled to a nuclear spin, c…

[Phys. Rev. A 92, 022340] Published Tue Aug 18, 2015

]]>We present two approaches to enhance the resolving power for measuring hyperfine structure constants using resonance ionization spectroscopy. The first method employs a 2D-resonance ionization spectroscopy scanning technique with pulsed, narrowband Ti:sapphire lasers (1 GHz linewidth), allowing us t…

[Phys. Rev. A 92, 022506] Published Tue Aug 18, 2015

]]>We present here the performance of a simultaneous dual-species matter-wave accelerometer for measuring the differential acceleration between two different atomic species (${}^{87}\mathrm{Rb}$ and ${}^{85}\mathrm{Rb}$). We study the expression and the extraction of the differential phase from the interferometer output. The differen…

[Phys. Rev. A 92, 023626] Published Tue Aug 18, 2015

]]>To formulate the zero modes in a finite-size system with spontaneous breakdown of symmetries in quantum field theory is not trivial, for in the naive Bogoliubov theory, one encounters difficulties such as phase diffusion, the absence of a definite criterion for determining the ground state, and infr…

[Phys. Rev. A 92, 023627] Published Tue Aug 18, 2015

]]>We outline a general perturbative method of evaluating scattering features of finite-range complex potentials and use it to examine complex perturbations of a rectangular barrier potential. In optics, these correspond to modulated refractive index profiles of the form $\mathfrak{n}\left(x\right)={n}_{0}+f\left(x\right)$, where ${n}_{0}$ is real,…

[Phys. Rev. A 92, 023831] Published Tue Aug 18, 2015

]]>Quantum polarization is investigated by means of a trajectory picture based on the Bohmian formulation of quantum mechanics. Relevant examples of classical-like two-mode field states are thus examined, namely, Glauber and SU(2) coherent states. Although these states are often regarded as classical, …

[Phys. Rev. A 92, 023832] Published Tue Aug 18, 2015

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