We investigate the Casimir free energy of a metallic film either sandwiched between two dielectric plates or in vacuum. It is shown that even for a thin film of several tens of nanometer thickness the Casimir free energy and pressure calculated with the Lifshitz theory using the Drude model and the …

[Phys. Rev. A 92, 042109] Published Tue Oct 13, 2015

]]>Any repeated use of a fixed experimental instrument is subject to memory effects. We design an estimation method uncovering the details of the underlying interaction between the system and the internal memory without having any experimental access to memory degrees of freedom. In such case, by defin…

[Phys. Rev. A 92, 042315] Published Tue Oct 13, 2015

]]>Using an isoclinic-point technique, we measured the ${D}_{1}$ collision shift by Xe, $\partial \left[\delta \nu \right]/\partial P$, and the exponent $\kappa $ of the shift's temperature dependence (i.e., $\delta \nu \sim {T}^{\kappa}$). As demonstrated in our examination of the Rb-Kr system [N. P. Wells *et al.*, Phys. Rev. A **89**, 052516 (2014)], the isoclinic point provides (…

[Phys. Rev. A 92, 042509] Published Tue Oct 13, 2015

]]>We present *ab initio* calculations for the double ionization of helium by fast proton impact, using the generalized-Sturmian-functions methodology and within a perturbative treatment of the projectile-target interaction. The cross-section information is extracted from the asymptotic behavior of the n…

[Phys. Rev. A 92, 042704] Published Tue Oct 13, 2015

]]>We excite ultracold rubidium atoms in a magneto-optical trap to a coherent superposition of the three $|{m}_{j}|$ sublevels of the $37{d}_{5/2}$ Rydberg state. After some delay, during which the relative phases of the superposition components can evolve, we apply an electric field pulse to ionize the Rydberg elec…

[Phys. Rev. A 92, 043412] Published Tue Oct 13, 2015

]]>The nonlinear absorption process and associated phase shift in coupled optical cavities are studied experimentally by observing optical resonance properties. In the coupled cavity configuration, two optical cavities, one for a fundamental beam and the other for a second-harmonic (SH) beam, are coupl…

[Phys. Rev. A 92, 043815] Published Tue Oct 13, 2015

]]>In traditional Hanbury Brown–Twiss (HBT) schemes, thermal intensity-intensity correlations (IICs) are phase insensitive. Here we propose a modified HBT scheme with phase conjugation to demonstrate phase-sensitive and nonfactorizable features of thermal IIC speckles. It shows that the novel phase-sen…

[Phys. Rev. A 92, 041802(R)] Published Mon Oct 12, 2015

]]>We propose a family of *local* $\mathcal{PT}$-symmetric photonic lattices with transverse refraction index gradient $\omega $, where the emergence of *stable* Bloch-Zener oscillations are controlled by the interplay of $\omega $ with the degree of non-Hermiticity $\gamma $ of the lattice. In the exact $\mathcal{PT}$-symmetric phase we identify a cond…

[Phys. Rev. A 92, 041803(R)] Published Mon Oct 12, 2015

]]>We report the theoretical prediction and experimental observation of averaging of stochastic events with an equivalent result of calculating the arithmetic mean (or sum) of a *rational* number of realizations of the process under test, not necessarily limited to an integer record of realizations, as d…

[Phys. Rev. A 92, 041804(R)] Published Mon Oct 12, 2015

]]>We introduce a conceptually simple and experimentally feasible method to realize and detect photonic topological Chern insulators with a one-dimensional circuit quantum electrodynamics lattice. By periodically modulating the couplings in this lattice, we show that this one-dimensional model can be m…

[Phys. Rev. A 92, 041805(R)] Published Mon Oct 12, 2015

]]>We analyze the role of the dynamical Casimir effect as a resource for quantum technologies, such as quantum cryptography and quantum metrology. In particular, we consider the generation of Einstein-Podolsky-Rosen steering and Gaussian interferometric power, two useful forms of asymmetric quantum cor…

[Phys. Rev. A 92, 042107] Published Mon Oct 12, 2015

]]>We establish a direct connection of quantum Markovianity of an open system to its classical counterpart by generalizing the criterion based on the information flow. Here the flow is characterized by the time evolution of Helstrom matrices, given by the weighted difference of statistical operators, u…

[Phys. Rev. A 92, 042108] Published Mon Oct 12, 2015

]]>Whereas in standard quantum-state tomography one estimates an unknown state by performing various measurements with known devices, and whereas in detector tomography one estimates the positive-operator-valued-measurement elements of a measurement device by subjecting to it various known states, we c…

[Phys. Rev. A 92, 042312] Published Mon Oct 12, 2015

]]>A discrete time quantum walk on the star network is considered, on which the walker has a waiting probability at any time step and for any of the $N$ nodes. This contrasts with a previous continuous time analysis, in which the walker in any of the $N-1$ leaf nodes is forced to jump back to the central h…

[Phys. Rev. A 92, 042313] Published Mon Oct 12, 2015

]]>The logic Bell-state which encodes many physical qubits in a logic qubit has great application potential in the future quantum communication field, for it is robust to the decoherence in a noisy environment. In this paper, we propose a complete logic Bell-state analysis (LBSA) with the help of the a…

[Phys. Rev. A 92, 042314] Published Mon Oct 12, 2015

]]>Participator resonant Auger decay spectra populating the $X,A,B$, and $C$ states of ${\mathrm{CO}}_{2}{}^{+}$ are recorded with angular and vibrational resolution for selected photon energies in the vicinity of the C $1s\to {\pi}^{*}$ resonance of ${\mathrm{CO}}_{2}$ using a narrow photon bandwidth and a high-resolution electron spectrometer. The me…

[Phys. Rev. A 92, 042506] Published Mon Oct 12, 2015

]]>The magic wavelength for an optical lattice for hydrogen atoms that cancels the lowest order ac Stark shift of the $1S\text{\u2212}2S$ transition is calculated to be 513 nm. The magnitudes of the ac Stark shift $\mathrm{\Delta}E=-119$ $\text{Hz}/(\text{kW}/{\mathrm{cm}}^{2})$ and the slope $d\mathrm{\Delta}E/d\nu =-2.77$ $\text{Hz}/(\text{GHz}\text{kW}/{\mathrm{cm}}^{2})$ at the magic wavelength suggest that a s…

[Phys. Rev. A 92, 042507] Published Mon Oct 12, 2015

]]>We calculated the spectra of the first six members of the Mg-like isoelectronic sequence using different approximations. The most accurate results were obtained with the configuration-interaction+all-order method (CI+AO), which provided relative accuracy for transition energies on the level of 0.1% …

[Phys. Rev. A 92, 042508] Published Mon Oct 12, 2015

]]>Knowledge of the detailed evolution of the whole charge-state distribution of projectile ions colliding with targets is required in several fields of research such as material science and atomic and nuclear physics but also in accelerator physics, and in particular in regard to the several foreseen …

[Phys. Rev. A 92, 042703] Published Mon Oct 12, 2015

]]>By photoionizing hyperfine (HF) levels of the Cs state $6{\phantom{\rule{0.16em}{0ex}}}^{2}{P}_{3/2}$ in a slow and cold atom beam, we find how their population depends on the excitation laser power. The long time (around $180\phantom{\rule{4pt}{0ex}}\mu \mathrm{s})$ spent by the slow atoms inside the resonant laser beam is large enough to enable exploration of a unique atom-l…

[Phys. Rev. A 92, 043408] Published Mon Oct 12, 2015

]]>We study the sensitive detection of a weak static magnetic field via Faraday rotation induced by an ensemble of spins in a bimodal degenerate microwave cavity. We determine the limit of the resolution for the sensitivity of the magnetometry achieved using either single-photon or multiphoton inputs. …

[Phys. Rev. A 92, 043409] Published Mon Oct 12, 2015

]]>We investigate the fast transport of an atom or a packet of atoms by different kinds of nonharmonic traps including power-law traps. The study is based on the reverse-engineering method. Exact results are obtained and applied to design robust transport protocols. The optimization of the transport tr…

[Phys. Rev. A 92, 043410] Published Mon Oct 12, 2015

]]>Using a three-dimensional semiclassical model that incorporates tunneling and Coulomb field effect, we investigate photoelectron angular distributions from single ionization of atoms in intense elliptically polarized laser fields. We have studied the photoelectron angular distributions of the first …

[Phys. Rev. A 92, 043411] Published Mon Oct 12, 2015

]]>Because of the inherent coupling, the influence from the phonon bath on the coherent energy exchange between a quantum-dot (QD) two-state system (TSS) and a resonant optical mode is a twofold action. One action is the influence on the construction of the coherence, and the other is on the constructe…

[Phys. Rev. A 92, 043811] Published Mon Oct 12, 2015

]]>The outstanding progress in nanostructure fabrication and cooling technologies allows what was unthinkable a few decades ago: bringing single-mode mechanical vibrations to the quantum regime. The coupling between photon and phonon excitations is a natural source of nonclassical states of light and m…

[Phys. Rev. A 92, 043812] Published Mon Oct 12, 2015

]]>Any lossless transformation on ${n}_{s}$ spatial and ${n}_{p}$ internal modes of light can be described by an ${n}_{s}{n}_{p}\times {n}_{s}{n}_{p}$ unitary matrix, but there is no known procedure to effect an arbitrary ${n}_{s}{n}_{p}\times {n}_{s}{n}_{p}$ unitary matrix on light in ${n}_{s}$ spatial and ${n}_{p}$ internal modes. We devise an algorithm to realize an arbitrary discr…

[Phys. Rev. A 92, 043813] Published Mon Oct 12, 2015

]]>We show that the frequency spectrum of two-dimensional photonic crystals is strongly influenced by Fano resonances which can be excited already in the linear array of dielectric cylinders. To support this claim, we calculate the transmission of an electromagnetic wave through a linear array of diele…

[Phys. Rev. A 92, 043814] Published Mon Oct 12, 2015

]]>In recent years, many efforts have been devoted to the construction of a proper measure of quantum non-Markovianity. However, those proposed measures are shown to be at variance in different situations. In this work, we utilize the theory of $k$-positive maps to generalize a hierarchy of $k$ divisibilit…

[Phys. Rev. A 92, 042105] Published Fri Oct 09, 2015

]]>We analyze the influence of relativistic effects on the minimum evolution time between two orthogonal states of a quantum system. Defining the initial state as a homogeneous superposition between two Hamiltonian eigenstates of an electron in a uniform magnetic field, we obtain a relation between the…

[Phys. Rev. A 92, 042106] Published Fri Oct 09, 2015

]]>Quantum annealing provides a promising route for the development of quantum optimization devices, but the usefulness of such devices will be limited in part by the range of implementable problems as dictated by hardware constraints. To overcome constraints imposed by restricted connectivity between …

[Phys. Rev. A 92, 042310] Published Fri Oct 09, 2015

]]>We implement a quantum-key-distribution protocol which works in analogy to the BB84 protocol with two discrete states each in frequency and time. Its security relies on the frequency-time uncertainty. We show how the protocol is realized with commercial telecom components and discuss technical const…

[Phys. Rev. A 92, 042311] Published Fri Oct 09, 2015

]]>An alternate method of two-photon spectroscopy is presented where cesium atoms interact with a phase-modulated laser beam. Doppler-free two-photon spectroscopy of the cesium atom $6S\to 8S$ hyperfine transition was used to experimentally demonstrate quantum interfered two-photon spectra. We calculated th…

[Phys. Rev. A 92, 042504] Published Fri Oct 09, 2015

]]>The critical nuclear charge ${Z}_{c}$ required for a heliumlike atom to have at least one bound state was recently determined with a high accuracy from variational calculations. Analysis of the wave functions further suggested that the bound state changes smoothly into a shape resonance as $Z$ crosses the cr…

[Phys. Rev. A 92, 042505] Published Fri Oct 09, 2015

]]>Percolation theory is applied to the phase-transition dynamics of domain pattern formation in segregating binary Bose-Einstein condensates in quasi-two-dimensional systems. Our finite-size-scaling analysis shows that the percolation threshold of the initial domain pattern emerging from the dynamic i…

[Phys. Rev. A 92, 043608] Published Fri Oct 09, 2015

]]>We study a non-Hermitian version of the Rabi model, where a two-level system is periodically driven with an imaginary-valued drive strength, leading to alternating gain and loss. In the Floquet picture, the model exhibits $\mathcal{PT}$ symmetry, which can be broken when the drive is sufficiently strong. We der…

[Phys. Rev. A 92, 042103] Published Thu Oct 08, 2015

]]>An atom attached to a micrometer-scale wire that is vibrating at a frequency $\sim 100\phantom{\rule{0.28em}{0ex}}\mathrm{MHz}$ and with displacement amplitude $\sim 1\phantom{\rule{0.28em}{0ex}}\mathrm{nm}$ experiences an acceleration magnitude $\sim {10}^{9}\phantom{\rule{0.28em}{0ex}}{\mathrm{m}\phantom{\rule{0.28em}{0ex}}\mathrm{s}}^{-2}$, approaching the surface gravity of a neutron star. As one application of such extreme noninertial forces in a mesoscopic setting, …

[Phys. Rev. A 92, 042104] Published Thu Oct 08, 2015

]]>We propose the square of convex-roof extended negativity (SCREN) as a powerful candidate to characterize strong monogamy of multiparty quantum entanglement. We first provide a strong monogamy inequality of multiparty entanglement using SCREN and show that the tangle-based multiqubit strong-monogamy …

[Phys. Rev. A 92, 042307] Published Thu Oct 08, 2015

]]>Many-body quantum eigenstates of generic Hamiltonians at finite-energy density typically satisfy the “volume law” of entanglement entropy: the von Neumann entanglement entropy and the Renyi entropies for a subregion scale in proportion to its volume. Here we provide a connection between the volume l…

[Phys. Rev. A 92, 042308] Published Thu Oct 08, 2015

]]>What can one do with a given tunable quantum device? We provide complete symmetry criteria deciding whether some effective target interaction(s) can be simulated by a set of given interactions. Symmetries lead to a better understanding of simulation and permit a reasoning beyond the limitations of t…

[Phys. Rev. A 92, 042309] Published Thu Oct 08, 2015

]]>We perform a detailed analysis of how the interplay between the residual binding potential and a strong laser field influences above-threshold ionization (ATI), employing a semianalytical, Coulomb-corrected strong-field approximation (SFA) in which the Coulomb potential is incorporated in the electr…

[Phys. Rev. A 92, 043407] Published Thu Oct 08, 2015

]]>An extension to a powerful technique for generating a sequence of short $\gamma $-ray pulses is proposed, where a set of several sequentially placed absorbers modulate the amplitudes and initial phases of the spectral components in the $\gamma $ ray with the resonant interaction between the light and the Doppler-shifted nuclear transitions.

[Phys. Rev. A 92, 043808] Published Thu Oct 08, 2015

]]>Electron dynamics excited by an optical near field (ONF) in a two-dimensional quantum dot model was investigated by solving a time-dependent Schrödinger equation. It was found that the ONF excitation of the electron caused two characteristic phenomena: a two-photon absorption and an induction of a m…

[Phys. Rev. A 92, 043809] Published Thu Oct 08, 2015

]]>We consider a two-dimensional homogeneous ensemble of cold bosonic atoms loaded inside two optical cavities and pumped by a far-detuned external laser field. We examine the conditions for these atoms to self-organize into triangular and honeycomb lattices as a result of superradiance. By collectivel…

[Phys. Rev. A 92, 043810] Published Thu Oct 08, 2015

]]>[Phys. Rev. A 92, 049901] Published Thu Oct 08, 2015

]]>The influence of cyclic electron delocalization associated with aromaticity on the high-order-harmonic generation (HHG) process is investigated in organic molecules. We show that the aromatic molecules benzene $\left({\mathrm{C}}_{6}{\mathrm{H}}_{6}\right)$ and furan $\left({\mathrm{C}}_{4}{\mathrm{H}}_{4}\mathrm{O}\right)$ produce high-order harmonics more efficiently than nonaromatic sy…

[Phys. Rev. A 92, 041801(R)] Published Wed Oct 07, 2015

]]>Interference effects in slow ${\mathrm{He}}^{2+}+\mathrm{H}\left(1s\right)$ charge-exchange collisions are analyzed within the framework of the dynamical adiabatic theory of atomic collisions. Analytic continuation of the dynamical adiabatic scaled-energy eigenvalues into the complex plane of internuclear separation $R$ for the ${\mathrm{HeH}}^{2+}$ …

[Phys. Rev. A 92, 042701] Published Wed Oct 07, 2015

]]>The linear polarization of x rays generated during a dielectronic recombination — an electron recombines with an ion and simultaneously excites a bound electron — is measured in good agreement with theoretical predictions, leading to a refined technique to diagnose the electron currents and magnetic fields in both high-temperature astrophysical and laboratory plasmas.

[Phys. Rev. A 92, 042702] Published Wed Oct 07, 2015

]]>We work out the theory and applications of a fast quasiadiabatic approach to speed up slow adiabatic manipulations of quantum systems by driving a control parameter as near to the adiabatic limit as possible over the entire protocol duration. We find characteristic time scales, such as the minimal t…

[Phys. Rev. A 92, 043406] Published Wed Oct 07, 2015

]]>We present a simple experimental scheme, based on standard atom-optics techniques, to design highly versatile model systems for the study of single-particle quantum transport phenomena. The scheme is based on a discrete set of free-particle momentum states that are coupled via momentum-changing two-…

[Phys. Rev. A 92, 043606] Published Wed Oct 07, 2015

]]>We study, within the framework of the classical-field approximation, the density correlations of a weakly interacting expanding Bose gas for the whole range of temperatures across the Bose-Einstein condensation threshold. We focus on elongated quasi-one-dimensional systems where there is a huge disc…

[Phys. Rev. A 92, 043607] Published Wed Oct 07, 2015

]]>We predict a sequence of magic-zero wavelengths for the Sr excited $5s5p{\phantom{\rule{0.16em}{0ex}}}^{3}{P}_{0}$ state, and provide a general roadmap for extracting transition matrix elements using precise frequency measurements. We demonstrate that such measurements can serve as a global benchmark of the spectroscopic accuracy that is …

[Phys. Rev. A 92, 040501(R)] Published Tue Oct 06, 2015

]]>Ergodicity, an essential property of a dynamical system for thermalization to occur, is found to be remarkably robust against disorder, which ultimately leads to many-body localization, and this robustness is predicted to be more significant in real-life-scale systems than in ultracold lattice experiments due to their limited size.

[Phys. Rev. A 92, 041601(R)] Published Tue Oct 06, 2015

]]>Optimal control theory is applied in the modern open-quantum-system framework to design systematically a sequence of microwave pulses that optimize the dynamic nuclear polarization, gaining an order-of-magnitude improvement in enhancing the nuclear polarization and consequently increasing the signal-to-noise ratio dramatically in the widely used technique of nuclear magnetic resonance (NMR) for detecting and/or imaging microstructures and biotissue.

[Phys. Rev. A 92, 042102] Published Tue Oct 06, 2015

]]>An exact analytic solution is presented for a two-state quantum system driven by a time-dependent external field with an exponential temporal shape in the presence of dephasing. In the absence of dephasing the model reduces to the well-known Demkov model originally introduced in slow atomic collisio…

[Phys. Rev. A 92, 043404] Published Tue Oct 06, 2015

]]>One of the challenges with quantum simulation in ion traps is that the effective spin-spin exchange couplings are not uniform across the lattice. This can be particularly important in Penning-trap realizations where the presence of an ellipsoidal boundary at the edge of the trap leads to dislocation…

[Phys. Rev. A 92, 043405] Published Tue Oct 06, 2015

]]>We consider soft-core bosons with on-site interaction loaded in the honeycomb lattice with different site energies for the two sublattices. Using both a mean-field approach and quantum Monte Carlo simulations, we show that the topology of the honeycomb lattice results in a nonvanishing Berry curvatu…

[Phys. Rev. A 92, 043605] Published Tue Oct 06, 2015

]]>We present polarization measurement of a Ni-like Ag x-ray laser working in the transient collisional excitation scheme. A calibrated membrane multilayer beam splitter was used to determine the energies of two mutually perpendicular polarization components ($s$ and $p$ components). As a result, we observ…

[Phys. Rev. A 92, 043807] Published Tue Oct 06, 2015

]]>We propose the use of non-equally-spaced decoupling pulses for high-resolution selective addressing of nuclear spins by a quantum sensor. The analytical model of the basic operating principle is supplemented by detailed numerical studies that demonstrate the high degree of selectivity and the robust…

[Phys. Rev. A 92, 042304] Published Mon Oct 05, 2015

]]>Parity measurement is a key step in many entanglement generation and quantum error correction schemes. We propose a protocol for nondestructive parity measurement of two remote qubits, i.e., macroscopically separated qubits with no direct interaction. The qubits are instead dispersively coupled to s…

[Phys. Rev. A 92, 042305] Published Mon Oct 05, 2015

]]>We define an entanglement witness in a composite quantum system as an observable having a nonnegative expectation value in every separable state. Then a state is entangled if and only if it has a negative expectation value of some entanglement witness. Equivalent representations of entanglement witn…

[Phys. Rev. A 92, 042306] Published Mon Oct 05, 2015

]]>Ultrafast relaxation dynamics in 2-methylfuran has been investigated by time-resolved photoelectron imaging. An “up” internal conversion from a low-lying state into a higher-lying one has been observed experimentally. Temporal photoelectron kinetic-energy distributions and angular distributions of t…

[Phys. Rev. A 92, 042501] Published Mon Oct 05, 2015

]]>We study the damping of the collective excitations of Bose-Einstein condensates in a harmonic trap potential loaded in an optical lattice. In the presence of a confining potential the system is inhomogeneous and the collective excitations are characterized by a set of discrete confined phononlike ex…

[Phys. Rev. A 92, 042502] Published Mon Oct 05, 2015

]]>We report the experimental value of electron affinity for TaC to be 1.928(0.056) eV by performing photodetachment of its anion at 355 nm. An excited-electronic state of the anion, stable against autodetachment, is observed lying 0.828 eV above the ground-electronic state. Five low-lying electronic s…

[Phys. Rev. A 92, 042503] Published Mon Oct 05, 2015

]]>We experimentally disentangle the contributions of different quantum paths in high-order-harmonic generation (HHG) from the spectrally and spatially resolved harmonic spectra. By adjusting the laser intensity and focusing position, we simultaneously observe the spectrum splitting, frequency shift, a…

[Phys. Rev. A 92, 043403] Published Mon Oct 05, 2015

]]>The transfer of orbital angular momentum from an optical vortex to an atomic Bose-Einstein condensate changes the vorticity of the condensate. The spatial mismatch between initial and final center-of-mass wave functions of the condensate significantly influences the two-photon optical dipole transit…

[Phys. Rev. A 92, 043603] Published Mon Oct 05, 2015

]]>An admixture of ${}^{87}$Rb and ${}^{171}$Yb atoms is prepared and cooled down to quantum degeneracy in a hybrid optical dipole trap independently tunable for both atomic species, which makes experimentalists ready to explore intriguing quantum phenomena such as the behavior of polarons on a lattice with alkali-metal–alkaline-earth-metal mixtures.

[Phys. Rev. A 92, 043604] Published Mon Oct 05, 2015

]]>We demonstrate ladder-type electromagnetically induced transparency (EIT) using an optical nanofiber suspended in a warm rubidium vapor. The signal and control fields are both guided along the nanofiber, which enables strong nonlinear interactions with the surrounding atoms at relatively low powers.…

[Phys. Rev. A 92, 043806] Published Mon Oct 05, 2015

]]>Various measures have been suggested recently for quantifying the coherence of a quantum state with respect to a given basis. We first use two of these, the ${l}_{1}$-norm and relative entropy measures, to investigate tradeoffs between the coherences of mutually unbiased bases. Results include relations be…

[Phys. Rev. A 92, 042101] Published Fri Oct 02, 2015

]]>The preparation of quantum states using short quantum circuits is one of the most promising near-term applications of small quantum computers, especially if the circuit is short enough and the fidelity of gates high enough that it can be executed without quantum error correction. Such quantum state …

[Phys. Rev. A 92, 042303] Published Fri Oct 02, 2015

]]>We investigate a shift of the maximum of photoelectron momentum distributions (PEMDs) produced in the ionization of a model atom by intense half-cycle and one-cycle circularly polarized pulses. Our analysis approaches the problem from two complementary directions: by solving the time-dependent Schrö…

[Phys. Rev. A 92, 043402] Published Fri Oct 02, 2015

]]>Making use of a generalized quantum theory of paraxial light propagation where the radiation-axis and the temporal coordinates play exchanged roles, we discuss the potential of bulk nonlinear optical media in cavityless configurations for quantum statistical mechanics studies of the conservative man…

[Phys. Rev. A 92, 043802] Published Fri Oct 02, 2015

]]>We describe a theoretical model, based on a density matrix and the Liouville equation, for the investigation of magneto-optical resonances in alkali-metal atomic vapor, in particular in the case of the electromagnetically induced transparency (EIT) in the presence of antirelaxation coatings. The inf…

[Phys. Rev. A 92, 043803] Published Fri Oct 02, 2015

]]>We study the optical forces acting on toroidal nanostructures. A great enhancement of optical force is unambiguously identified as originating from the toroidal dipole resonance based on the source representation, where the distribution of the induced charges and currents is characterized by the thr…

[Phys. Rev. A 92, 043804] Published Fri Oct 02, 2015

]]>The propagation of electromagnetic waves in isotropic dielectric media with local dispersion is studied under the assumption of small but nonvanishing $\lambda /\ell $, where $\lambda $ is the wavelength and $\ell $ is the characteristic inhomogeneity scale. It is commonly known that, due to nonzero $\lambda /\ell $, such waves can experie…

[Phys. Rev. A 92, 043805] Published Fri Oct 02, 2015

]]>Classical satisfiability (SAT) and quantum satisfiability (QSAT) are complete problems for the complexity classes NP and QMA, respectively, and they are believed to be intractable for both classical and quantum computers. Statistical ensembles of instances of these problems have been studied previou…

[Phys. Rev. A 92, 040301(R)] Published Thu Oct 01, 2015

]]>Removing a single logical gate from a classical information processor renders this processor useless. This is not so for a quantum information processor. A large number of quantum gates may be removed without significantly affecting the processor's performance. In this paper, focusing on the quantum…

[Phys. Rev. A 92, 042301] Published Thu Oct 01, 2015

]]>We present a device-independent quantum scheme for the *Byzantine generals* problem. The protocol is for three parties. Party $C$ is to send two identical one-bit messages to parties $A$ and $B$. The receivers $A$ and $B$ may exchange two one-bit messages informing the other party on the message received from $C$…

[Phys. Rev. A 92, 042302] Published Thu Oct 01, 2015

]]>We resolve the strong-field single ionization of acetylene into different channels by differentially normalizing the lateral momenta of the directly escaped electrons from the aligned and antialigned molecules. Distinct electron momentum distributions for different channels are observed using both n…

[Phys. Rev. A 92, 043401] Published Thu Oct 01, 2015

]]>In the present work, we investigate how single- and multi-vortex-ring states can emerge from a planar dark soliton in three-dimensional (3D) Bose-Einstein condensates (confined in isotropic or anisotropic traps) through bifurcations. We characterize such bifurcations quantitatively using a Galerkin-…

[Phys. Rev. A 92, 043601] Published Thu Oct 01, 2015

]]>We consider the time evolution of a dilute atomic Fermi gas after release from a trapping potential. A common difficulty with using fluid dynamics to study the expansion of the gas is that the theory is not applicable in the dilute corona, and that a naive treatment of the entire cloud using fluid d…

[Phys. Rev. A 92, 043602] Published Thu Oct 01, 2015

]]>We report on the dependence of the carrier frequency of a nondiffracting optical pulse on the amount of orbital angular momentum it carries. We provide a unified universal form of such a dependence for the cases of both scalar and vector pulses with arbitrary frequency spectra. For the case of parax…

[Phys. Rev. A 92, 043801] Published Thu Oct 01, 2015

]]>In this work, the effects from one-pion exchange in $ep$ and $\mu p$ bound states by two-photon coupling are discussed. We at first calculate the effective couplings of a pion with a lepton (electron or muon) by two-photon coupling and the corresponding effective nonrelativistic potential. Then we calculat…

[Phys. Rev. A 92, 032512] Published Wed Sep 30, 2015

]]>We show that the photoionization dynamics from the innermost shell of atoms changes significantly when instead of single atoms an ordered group of atoms or a crystal is considered. We find that the electronic current away from a given atom induced by pulsed photoionization is strongly suppressed in …

[Phys. Rev. A 92, 033424] Published Wed Sep 30, 2015

]]>We present reduced-dimensional stochastic projected Gross-Pitaevskii equations describing regimes of confinement and temperature where a one-dimensional (1D) or 2D superfluid is immersed in a 3D thermal cloud. The projection formalism provides both a formally rigorous and physically natural way to e…

[Phys. Rev. A 92, 033631] Published Wed Sep 30, 2015

]]>A regime of extreme self-compression of optical solitons to single-cycle duration with further shortening along with superbroad spectrum up-shifting is revealed when the Kerr nonlinearity and ionization process are independently controlled. This results in efficient optical-pulse compression as a wh…

[Phys. Rev. A 92, 033856] Published Wed Sep 30, 2015

]]>Filamentation and supercontinuum generation with 1.3-ps, 1055-nm laser pulses in YAG crystal is investigated numerically and experimentally. Numerical simulations based on solving the unidirectional nonparaxial propagation equation uncover that the self-focusing dynamics of a picosecond laser pulse …

[Phys. Rev. A 92, 033857] Published Wed Sep 30, 2015

]]>[Phys. Rev. A 92, 039906] Published Wed Sep 30, 2015

]]>We have in mind a register of qubits for an quantum information system, and consider its decoherence in an idealized but typical situation. Spontaneous decay and other couplings to the far environment, considered as the world outside the quantum apparatus, will be neglected, while couplings to quant…

[Phys. Rev. A 92, 030104(R)] Published Tue Sep 29, 2015

]]>We present a theoretical framework for describing an impurity in a trapped Bose system in one spatial dimension. The theory handles any external confinement, arbitrary mass ratios, and a weak interaction may be included between the Bose particles. To demonstrate our technique, we calculate the groun…

[Phys. Rev. A 92, 031601(R)] Published Tue Sep 29, 2015

]]>In most torsion pendulum experiments, the force resolution is dominantly limited by thermal noise, which is proportional to the pendulum's intrinsic rigidity. Thus, increasing the rigidity directly, such as through increasing torsion fiber's diameter, will decrease the resolution. Here, we present a…

[Phys. Rev. A 92, 032131] Published Tue Sep 29, 2015

]]>It is an established fact that entanglement is a resource. Sharing an entangled state leads to nonlocal correlations and to violations of Bell inequalities. Such nonlocal correlations illustrate the advantage of quantum resources over classical resources. In this paper, we quantitatively study Bell …

[Phys. Rev. A 92, 032329] Published Tue Sep 29, 2015

]]>A significant problem facing next-generation quantum technologies is how to generate and manipulate macroscopic entanglement in light and matter systems. Here we report a regime of dynamical light-matter behavior in which a giant, system-wide entanglement is generated by varying the light-matter cou…

[Phys. Rev. A 92, 032330] Published Tue Sep 29, 2015

]]>We introduce the concepts of cohering and decohering power of quantum channels. Using the axiomatic definition of the coherence measure, we show that the optimization required for calculations of these measures can be restricted to pure input states and hence greatly simplified. We then use two exam…

[Phys. Rev. A 92, 032331] Published Tue Sep 29, 2015

]]>Experimental cross sections for single and double ionization of ${\mathrm{H}}_{2}\mathrm{O}$ by swift ${\mathrm{H}}^{+}$ with energy ranging from 0.3 to 2.0 MeV are reported. In this energy range the ionization is the dominant collision process and charge transfer reactions can be disregarded. A multihit coincidence technique is used to me…

[Phys. Rev. A 92, 032714] Published Tue Sep 29, 2015

]]>There is an increasing interest in the extraction and control of the interfering quantum pathway amplitudes induced by control fields during laser-matter interactions. The Hamiltonian-encoding and observable-decoding (HE-OD) technique has been introduced for extracting the amplitudes of the pathways…

[Phys. Rev. A 92, 033423] Published Tue Sep 29, 2015

]]>We analyze the mean-field yrast spectrum of a two-component Bose gas in the ring geometry with arbitrary interaction asymmetry. Of particular interest is the possibility that the yrast spectrum develops local minima at which persistent superfluid flow can occur. By analyzing the mean-field energy fu…

[Phys. Rev. A 92, 033630] Published Tue Sep 29, 2015

]]>We present a heralded photon source based only on linear optics and weak coherent states. By time-tuning a Hong-Ou-Mandel interferometer fed with frequency-displaced coherent states, the output photons can be synchronously heralded following sub-Poisson statistics, which is indicated by the second-o…

[Phys. Rev. A 92, 033855] Published Tue Sep 29, 2015

]]>We report the creation of ultra-long-range ${\mathrm{Sr}}_{2}$ molecules comprising one ground-state $5{s}^{2}$ ${}^{1}{S}_{0}$ atom and one atom in a $5sns$ ${}^{3}{S}_{1}$ Rydberg state for $n$ ranging from 29 to 36. Molecules are created in a trapped ultracold atomic gas using two-photon excitation near resonant with the $5s5p$ ${}^{3}{P}_{1}$ intermediate sta…

[Phys. Rev. A 92, 031403(R)] Published Mon Sep 28, 2015

]]>We apply a distance-based Bell-test analysis method [E. Knill *et al.*, Phys. Rev. A **91**, 032105 (2015)] to three experimental data sets where conventional analyses failed or required additional assumptions. The first is produced from a classical source exploiting a “coincidence-time loophole” for whi…

[Phys. Rev. A 92, 032130] Published Mon Sep 28, 2015

]]>We investigate entanglement and quantum phase transition in a two-dimensional Heisenberg anisotropic spin-$1/2\mathit{XY}$ model, using the quantum renormalization-group method (QRG) on a square lattice of $N\times N$ sites. The entanglement through geometric average of concurrences is calculated after each step of th…

[Phys. Rev. A 92, 032327] Published Mon Sep 28, 2015

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