We present a procedure to completely determine the complex modular values of arbitrary observables of pre- and postselected ensembles, which works experimentally for all measurement strengths and all postselected states. This procedure allows us to discuss the physics of modular and weak values in i…

[Phys. Rev. A 93, 042124] Published Thu Apr 28, 2016

]]>Estimation of channel parameters is important for extending the range and increasing the key rate of continuous-variable quantum key distribution protocols. We propose an estimator for the channel noise parameter based on the method-of-moments. The method-of-moments finds an estimator from the momen…

[Phys. Rev. A 93, 042343] Published Thu Apr 28, 2016

]]>We present an experimental and computational analysis of dissociative double ionization of ${\mathrm{N}}_{2}$ and CO molecules under electron impact. Experiments are performed at three energies, viz. 1, 3, and 5 keV, in order to observe the effect of impact energy on the dissociative ionization kinematics. We compa…

[Phys. Rev. A 93, 042712] Published Thu Apr 28, 2016

]]>We use Rabi spectroscopy to explore the low-energy excitation spectrum of a finite-temperature Bose gas of rubidium atoms across the phase transition to a Bose-Einstein condensate (BEC). To record this spectrum, we coherently drive the atomic population between two spin states. A small relative disp…

[Phys. Rev. A 93, 043624] Published Thu Apr 28, 2016

]]>We study the ground-state phases of a spin-orbit-coupled Bose-Einstein condensate loaded in a two-dimensional optical lattice. We find three types of helical supersolid phases, which are dependent on the anisotropy of the spin-orbit coupling with respect to the relative strength of the $y$ and $x$ direc…

[Phys. Rev. A 93, 043625] Published Thu Apr 28, 2016

]]>Applying large magnetic fields to gain access to the hyperfine Paschen-Back regime can isolate three-level systems in a hot alkali metal vapors, thereby simplifying usually complex atom-light interactions. We use this method to make the first direct measurement of the $|\langle 5P|\left|er\right||5D\rangle |$ matrix element i…

[Phys. Rev. A 93, 043854] Published Thu Apr 28, 2016

]]>Recently, different proposals for generating isolated attosecond pulses with elliptical polarization have emerged. In this comprehensive study, two schemes based on the noncollinear interaction of two counter-rotating circularly polarized lasers beams are analyzed, showing a mechanism to produce isolated pulses of pure circular polarization.

[Phys. Rev. A 93, 043855] Published Thu Apr 28, 2016

]]>[Phys. Rev. A 93, 049906] Published Thu Apr 28, 2016

]]>Measuring the power spectral density of a stochastic process, such as a stochastic force or magnetic field, is a fundamental task in many sensing applications. Quantum noise is becoming a major limiting factor to such a task in future technology, especially in optomechanics for temperature, stochast…

[Phys. Rev. A 93, 042121] Published Wed Apr 27, 2016

]]>We present a phase-space study of a non-Hermitian Hamiltonian with $\mathcal{PT}$ symmetry based on the Wigner distribution function. For an arbitrary complex potential, we derive a generalized continuity equation for the Wigner function flow and calculate the related circulation values. Studying the vicinity o…

[Phys. Rev. A 93, 042122] Published Wed Apr 27, 2016

]]>We derive a quantum master equation for an atom coupled to a heat bath represented by a charged particle many-body environment. In the Born-Markov approximation, the influence of the plasma environment on the reduced system is described by the dynamical structure factor. Expressions for the profiles…

[Phys. Rev. A 93, 042711] Published Wed Apr 27, 2016

]]>We investigate the resonance-like enhancement (RLE) in high-order above-threshold ionization (ATI) spectra of the polyatomic molecules ${\mathrm{C}}_{2}{\mathrm{H}}_{4}$ and ${\mathrm{C}}_{2}{\mathrm{H}}_{6}$. In the spectrum-intensity maps, strong and weak RLE areas emerge alternatively for both ${\mathrm{C}}_{2}{\mathrm{H}}_{4}$ and ${\mathrm{C}}_{2}{\mathrm{H}}_{6}$ but in different sequences. Theoretical calculat…

[Phys. Rev. A 93, 043422] Published Wed Apr 27, 2016

]]>We present experimental work for improved atom loading in the optical molasses of a cesium fountain clock, employing a low-velocity intense source of atoms [Lu *et al.*, Phys. Rev. Lett **77**, 3331 (1996)], which we modify by adding a dark-state pump laser. With this modification the atom source has a m…

[Phys. Rev. A 93, 043423] Published Wed Apr 27, 2016

]]>It is well known that ions stored in a Paul trap, one of the most versatile tools in atomic, molecular, and optical (AMO) physics, may undergo a transition from a disordered cloud state to a geometrically well-ordered crystalline state, the Wigner crystal. In this paper we predict that close to the …

[Phys. Rev. A 93, 043424] Published Wed Apr 27, 2016

]]>The dynamic behavior of vortex pairs in two-component coherently (*Rabi*) coupled Bose-Einstein condensates is investigated in the presence of harmonic trapping. We discuss the role of the surface tension associated with the domain wall connecting two vortices in condensates of atoms occupying differe…

[Phys. Rev. A 93, 043623] Published Wed Apr 27, 2016

]]>Coupling a quantum many-body system to a cavity can create bifurcation points in its phase diagram, where the ground state makes sudden switchings between different phases. Here we study the dynamical quantum phase transition of a transverse field Ising model coupled to a cavity. We show that an inf…

[Phys. Rev. A 93, 043850] Published Wed Apr 27, 2016

]]>We present a unified approach to cascaded stimulated Brillouin scattering and frequency-comb generation in which the multitude of interacting pump, Stokes, and anti-Stokes optical fields is described by a single forward wave and a single backward wave at a single carrier frequency. The envelopes of …

[Phys. Rev. A 93, 043851] Published Wed Apr 27, 2016

]]>In the scheme recently proposed by M. Scala *et al.* [Phys. Rev. Lett. **111**, 180403 (2013)], a gravity-dependent phase shift is induced on the spin of a nitrogen-vacancy (NV) center in a trapped nanodiamond by the interaction between its magnetic moment and the quantized motion of the particle. This pr…

[Phys. Rev. A 93, 043852] Published Wed Apr 27, 2016

]]>We investigate the supersymmetry (SUSY) structures for inductor-capacitor circuit networks on a simple regular graph and its line graph. We show that their eigenspectra must coincide (except, possibly, for the highest eigenfrequency) due to SUSY, which is derived from the topological nature of the c…

[Phys. Rev. A 93, 043853] Published Wed Apr 27, 2016

]]>[Phys. Rev. A 93, 049904] Published Wed Apr 27, 2016

]]>[Phys. Rev. A 93, 049905] Published Wed Apr 27, 2016

]]>The experimentally measured cross section for super energy transfer collisions between a hyperthermal H atom and an ambient molecule is presented here. This measurement substantiates an emerging energy transfer mechanism with significant cross section, whereby a major fraction of atomic translation…

[Phys. Rev. A 93, 040702(R)] Published Tue Apr 26, 2016

]]>We demonstrate a technique for cooling a degenerate Fermi gas in a crossed-beam optical dipole trap, where high-energy atoms can be selectively removed from the trap by modulating the stiffness of the trapping potential with anharmonic trapping frequencies. We measure the dependence of the cooling e…

[Phys. Rev. A 93, 041401(R)] Published Tue Apr 26, 2016

]]>We address the dynamics of quantum correlations for a bipartite continuous-variable quantum system interacting with its fluctuating environment. In particular, we consider two independent quantum oscillators initially prepared in a Gaussian state, e.g., a squeezed thermal state, and compare the dyna…

[Phys. Rev. A 93, 042119] Published Tue Apr 26, 2016

]]>It is shown that a convex combination of two non-Markovian evolutions may lead to a Markovian semigroup. This shows that the convex combination of quantum evolutions displaying nontrivial memory effects may result in a perfectly memoryless evolution.

[Phys. Rev. A 93, 042120] Published Tue Apr 26, 2016

]]>We provide a characterization of memory effects in non-Markovian system-bath interactions from a quantum information perspective. More specifically, we establish sufficient conditions for which generalized measures of multipartite quantum, classical, and total correlations can be used to quantify th…

[Phys. Rev. A 93, 042337] Published Tue Apr 26, 2016

]]>The future of quantum repeater networking will require interoperability between various error-correcting codes. A few specific code conversions and even a generalized method are known, however, no detailed analysis of these techniques in the context of quantum networking has been performed. In this …

[Phys. Rev. A 93, 042338] Published Tue Apr 26, 2016

]]>A robust control over quantum dynamics is of paramount importance for quantum technologies. Many of the existing control techniques are based on smooth Hamiltonian modulations involving repeated calculations of basic unitaries resulting in time complexities scaling rapidly with the length of the con…

[Phys. Rev. A 93, 042339] Published Tue Apr 26, 2016

]]>A permutation-invariant code on $m$ qubits is a subspace of the symmetric subspace of the $m$ qubits. We derive permutation-invariant codes that can encode an increasing amount of quantum information while suppressing leading-order spontaneous decay errors. To prove the result, we use elementary number …

[Phys. Rev. A 93, 042340] Published Tue Apr 26, 2016

]]>One of the great challenges of electronic structure theory is the quest for the exact functional of density functional theory. Its existence is proven, but it is a complicated multivariable functional that is almost impossible to conceptualize. In this paper the asymmetric two-site Hubbard model is …

[Phys. Rev. A 93, 042511] Published Tue Apr 26, 2016

]]>A dispersionally corrected Gaussian profile describing Doppler-broadened spectral line shapes is presented. Proposed corrections include the frequency dependence of the Doppler shifting caused by dispersion as well as by light frequency variation over the whole spectral line shape. It is shown that …

[Phys. Rev. A 93, 042512] Published Tue Apr 26, 2016

]]>The recent progress in designing optical lattice clocks with fractional uncertainties below ${10}^{-17}$ requires unprecedented precision in estimating the role of higher-order effects of atom-lattice interactions. In this paper, we present results of systematic theoretical evaluations of the multipole, no…

[Phys. Rev. A 93, 043420] Published Tue Apr 26, 2016

]]>We investigate the impact of a rotating-wall potential on perpendicular laser cooling in a Penning ion trap. By including energy exchange with the rotating wall, we extend previous Doppler laser-cooling theory and show that low perpendicular temperatures are more readily achieved with a rotating wal…

[Phys. Rev. A 93, 043421] Published Tue Apr 26, 2016

]]>We examine analytically and numerically the spectral properties of three quasi-one-dimensional lattices, namely, kagome, Lieb, and stub lattices, which are characterized for having flatbands in their spectrum. It is observed that the degenerate eigenmodes modes of these flatbands form a Starklike la…

[Phys. Rev. A 93, 043847] Published Tue Apr 26, 2016

]]>The tuning of odd and even high-order harmonics of ultrashort pulses along the strong resonance of laser-produced indium plasma using an optical parametric amplifier of white-light continuum radiation (1250–1400 nm) allowed observation of different harmonics enhanced in the vicinity of the $4{d}^{10}5{s}^{2}\phantom{\rule{0.16em}{0ex}}{}^{1}{S}_{\mathrm{\dots}}$

[Phys. Rev. A 93, 043848] Published Tue Apr 26, 2016

]]>Applying a multiphoton-subtraction technique to the two-color macroscopic squeezed vacuum state of light generated via high-gain parametric down-conversion we conditionally prepare a different state of light: bright multimode low-noise twin beams. A lower noise in the sum of the photon numbers opens…

[Phys. Rev. A 93, 043849] Published Tue Apr 26, 2016

]]>We propose a feasible scheme to implement a universal set of quantum gates based on geometric phases and superadiabatic quantum control. Consolidating the advantages of both strategies, the proposed quantum gates are robust and fast. The diamond nitrogen-vacancy center system is adopted as a typical…

[Phys. Rev. A 93, 040305(R)] Published Mon Apr 25, 2016

]]>The eigenvalues of a non-Hermitian Hamilton operator are complex and provide not only the energies but also the lifetimes of the states of the system. They show a nonanalytical behavior at singular (exceptional) points (EPs). The eigenfunctions are biorthogonal, in contrast to the orthogonal eigenfu…

[Phys. Rev. A 93, 042116] Published Mon Apr 25, 2016

]]>We present a self-consistent mean-field model based on a two-component Pauli-like equation that incorporates quantum and relativistic effects (up to second order in $1/c$) for both external and internal electromagnetic fields. By taking the semirelativistic limit of the Dirac-Maxwell equations in the …

[Phys. Rev. A 93, 042117] Published Mon Apr 25, 2016

]]>One of the central features of quantum theory is that there are pairs of quantum observables that cannot be measured simultaneously. This incompatibility of quantum observables is a necessary ingredient in several quantum phenomena, such as measurement uncertainty relations, violation of Bell inequa…

[Phys. Rev. A 93, 042118] Published Mon Apr 25, 2016

]]>We study families of positive and completely positive maps acting on a bipartite system ${\mathbb{C}}^{M}\otimes {\mathbb{C}}^{N}$ (with $M\le N$). The maps have a property that, when applied to any state (of a given entanglement class), result in a separable state or, more generally, a state of another certain entanglement class (e.g., Sch…

[Phys. Rev. A 93, 042335] Published Mon Apr 25, 2016

]]>Inspired by the experimental measurement of the Rényi entanglement entropy in a lattice of ultracold atoms by Islam *et al.* [Nature (London) **528**, 77 (2015)], we propose a method to entangle two spatially separated qubits using the quantum many-body state as a resource. Through local operations access…

[Phys. Rev. A 93, 042336] Published Mon Apr 25, 2016

]]>Density-functional theory (DFT) is notorious for the absence of gradient corrections to the two-dimensional (2D) Thomas-Fermi kinetic-energy functional; it is widely accepted that the 2D analog of the 3D von Weizsäcker correction vanishes, together with all higher-order corrections. Contrary to this…

[Phys. Rev. A 93, 042510] Published Mon Apr 25, 2016

]]>The process of electron-loss to the continuum (ELC) has been studied for the collision systems ${\mathrm{U}}^{28+}+{\mathrm{H}}_{2}$ at a collision energy of 50 MeV/u, ${\mathrm{U}}^{28+}+{\mathrm{N}}_{2}$ at 30 MeV/u, and ${\mathrm{U}}^{28+}+\mathrm{Xe}$ at 50 MeV/u. The energy distributions of cusp electrons emitted at an angle of ${0}^{\circ}$ with respect to the projectile beam were measur…

[Phys. Rev. A 93, 042709] Published Mon Apr 25, 2016

]]>Observation of Auger electron emission from Al under the impact of He ions, at energies below the excitation threshold of Al-Al collisions, gives evidence for charge transfer in He-Al collisions. Excitation of $2p$-shell electrons in Al is produced by vacancy transfer, following double excitation of H…

[Phys. Rev. A 93, 042710] Published Mon Apr 25, 2016

]]>The direct ionization of the helium atom by intense coherent high-frequency short laser pulses is investigated theoretically from first principles. To this end, we solve numerically the time-dependent Schrödinger equation for the two-electron wave packet and its interaction with the linearly polariz…

[Phys. Rev. A 93, 043418] Published Mon Apr 25, 2016

]]>We investigate the composite adiabatic passage (CAP) reported by B. T. Torosov *et al.* [Phys. Rev. Lett. **106**, 233001 (2011)] in a nonlinear two-level system in which the level energies depend on the occupation of the levels, representing a mean-field type of interaction between the particles. A high-…

[Phys. Rev. A 93, 043419] Published Mon Apr 25, 2016

]]>We theoretically investigate two-particle and ground-state many-particle Anderson localizations of a spin-orbit coupled ultracold atomic Fermi gas trapped in a quasiperiodic potential and subjected to an out-of-plane Zeeman field. We solve exactly the two-particle problem in a finite length system b…

[Phys. Rev. A 93, 043621] Published Mon Apr 25, 2016

]]>The dynamical instability of weakly interacting two-component Bose-Einstein condensates with coaxial quantized vortices is analytically investigated in a two-dimensional isotopic harmonic potential. We examine whether complex eigenvalues appear on the Bogoliubov–de Gennes equation, implying dynamica…

[Phys. Rev. A 93, 043622] Published Mon Apr 25, 2016

]]>We analyze the correlation properties of light in nonlinear waveguides and transmission lines, predict the position-momentum realization of the Einstein-Podolsky-Rosen paradox for photon pairs in Kerr-type nonlinear photonic circuits, and we show how two-photon entangled states can be generated and …

[Phys. Rev. A 93, 043842] Published Mon Apr 25, 2016

]]>In this work we develop a semianalytical variational *Ansatz* to study the properties of few-photon excitations interacting with a collection of quantum emitters in regimes that go beyond the rotating-wave approximation. This method can be used to approximate both the static and dynamical properties o…

[Phys. Rev. A 93, 043843] Published Mon Apr 25, 2016

]]>We report an efficient mechanism to generate a squeezed state of a mechanical mirror in an optomechanical system. We use an especially tuned parametric amplifier (PA) inside the cavity and the parametric photon phonon processes to transfer quantum squeezing from photons to phonons with almost 100% e…

[Phys. Rev. A 93, 043844] Published Mon Apr 25, 2016

]]>The concept of directionally unbiased optical multiports is introduced, in which photons may reflect back out the input direction. A linear-optical implementation is described, and the simplest three-port version studied. Symmetry arguments demonstrate potential for unusual quantum information proce…

[Phys. Rev. A 93, 043845] Published Mon Apr 25, 2016

]]>The optical isolation functionality is of key importance in many photonic systems. However, a robust optical isolation is rather challenging to obtain due to the weak nonreciprocal response of conventional materials. Here, we theoretically explore novel solutions to obtain one-way propagation of cir…

[Phys. Rev. A 93, 043846] Published Mon Apr 25, 2016

]]>A general method is devised to determine if any given measurement can be implemented by “local operations and classical communication” (LOCC) alone, leading to fundamental results in quantum measurement theory. The procedure proves the impossibility of a measurement by LOCC even when an infinite number of rounds of communication are allowed.

[Phys. Rev. A 93, 042334] Published Fri Apr 22, 2016

]]>In one dimension, one can dissect a scattering potential $v\left(x\right)$ into pieces ${v}_{i}\left(x\right)$ and use the notion of the transfer matrix to determine the scattering content of $v\left(x\right)$ from that of ${v}_{i}\left(x\right)$. This observation has numerous practical applications in different areas of physics. The problem of finding an anal…

[Phys. Rev. A 93, 042707] Published Fri Apr 22, 2016

]]>Recently, a new type of Feshbach resonance, i.e., orbital Feshbach resonance (OFR), was proposed for the ultracold alkaline-earth-metal–like atoms and was experimentally observed in the ultracold gases of ${}^{173}\mathrm{Yb}$ atoms. Unlike most of the magnetic Feshbach resonances of ultracold alkali atoms, when th…

[Phys. Rev. A 93, 042708] Published Fri Apr 22, 2016

]]>One-dimensional Bose-Hubbard models are well known to obey a transition from regular to quantum-chaotic spectral statistics. We are extending this concept to relatively simple two-dimensional many-body models. Also in two dimensions a transition from regular to chaotic spectral statistics is found a…

[Phys. Rev. A 93, 043620] Published Fri Apr 22, 2016

]]>We report on the temporal pulse characteristics of individual harmonics in an attosecond pulse train by means of photoelectron streaking in a strong low-frequency transient. The scheme allows one to retrieve the pulse durations and first-order chirp of individual harmonics without the need for tempo…

[Phys. Rev. A 93, 043838] Published Fri Apr 22, 2016

]]>We consider the coupling of two optical waveguides in the few-cycle regime. The analysis is performed in the frame of a generalized Kadomtsev-Petviashvili model. A set of two coupled modified Korteweg–de Vries equations is derived, and it is shown that three types of coupling can occur, involving th…

[Phys. Rev. A 93, 043839] Published Fri Apr 22, 2016

]]>We theoretically investigate the dipolar molecular system driven by monochromatic periodic, linear, parabolic, and ${\mathrm{sech}}^{2}$ forms external fields, respectively. The two-level Hamiltonian model with nonzero diagonal dipole matrix elements is adopted to describe the population dynamics of the driven dipo…

[Phys. Rev. A 93, 043840] Published Fri Apr 22, 2016

]]>Due to the existence of quantum correlations between photon pairs, their average position can be determined more precisely than the individual position of each photon. This effect is exploited to enhance the precision and the resolution of measuring optical displacements.

[Phys. Rev. A 93, 043841] Published Fri Apr 22, 2016

]]>[Phys. Rev. A 93, 049903] Published Fri Apr 22, 2016

]]>We demonstrate how to create localized $\mathcal{PT}$-symmetric directionally invisible scatterers directly from a governing wave equation. Moreover, we can construct general non-$\mathcal{PT}$-symmetric objects which exhibit directional invisibility, though such an effect is typically associated with $\mathcal{PT}$-symmetric objects.…

[Phys. Rev. A 93, 041803(R)] Published Thu Apr 21, 2016

]]>Quantum Fisher information (QFI) is a key concept in quantum state estimation, and Berry curvature (BC) is another basic concept to describe geometric properties of quantum states. In this paper, we consider pure states undergoing unitary parametrization processes and show that the BC serves as a lo…

[Phys. Rev. A 93, 042115] Published Thu Apr 21, 2016

]]>We use the Koashi-Imoto decomposition of the degrees of freedom of joint system-environment initial states to investigate the reduced dynamics. We show that a subset of joint system-environment initial states guarantees completely positive reduced dynamics if and only if the system privately owns al…

[Phys. Rev. A 93, 042332] Published Thu Apr 21, 2016

]]>We model repetitive quantum error correction (QEC) with the single-error-correcting five-qubit code on a network of individually controlled qubits with always-on Ising couplings. We use our previously designed universal set of quantum gates based on sequences of shaped decoupling pulses. In addition…

[Phys. Rev. A 93, 042333] Published Thu Apr 21, 2016

]]>We investigate the nonsequential double ionization (NSDI) process of an atom in IR+XUV two-color intense laser fields, where the photon energy of the XUV laser is higher than the atomic ionization threshold. By using the frequency-domain theory, we consider the NSDI as a process caused by the collis…

[Phys. Rev. A 93, 043417] Published Thu Apr 21, 2016

]]>We propose a simple scheme for the realization of a topological quasienergy band structure with ultracold atoms in a periodically driven optical square lattice. It is based on a circular lattice shaking in the presence of a superlattice that lowers the energy on every other site. The topological ban…

[Phys. Rev. A 93, 043618] Published Thu Apr 21, 2016

]]>This work contains a detailed analysis of the properties of the ground state of a two-component two-site Bose-Hubbard model, which captures the physics of a binary mixture of Bose-Einstein condensates trapped in a double-well potential. The atom-atom interactions within each species and among the tw…

[Phys. Rev. A 93, 043619] Published Thu Apr 21, 2016

]]>We have experimentally determined the terahertz- (THz-) wave parametric gain of stimulated Raman scattering (SRS) by phonon-polaritons in $\mathrm{LiNb}{\mathrm{O}}_{3}$. Our approach is based on ultrabright THz-wave generation from SRS under stimulated Brillouin scattering suppression with subnanosecond pump pulses. To obt…

[Phys. Rev. A 93, 043836] Published Thu Apr 21, 2016

]]>We investigate spontaneous four-wave mixing (SFWM) in a single-channel side-coupled integrated spaced sequence of resonators (SCISSOR). Analytic expressions for the number of photon pairs generated, as well as the biphoton wave function (joint spectral amplitude) describing the pairs, are derived an…

[Phys. Rev. A 93, 043837] Published Thu Apr 21, 2016

]]>We present a model of quantum metrology inspired by the computational model known as deterministic quantum computation with one quantum bit (DQC1). Using only one pure qubit together with $l$ fully mixed qubits we obtain measurement precision (defined as root-mean-square error for the parameter being …

[Phys. Rev. A 93, 040304(R)] Published Wed Apr 20, 2016

]]>It has been argued that it is incompatible to maintain unitary time evolution for time-dependent non-Hermitian Hamiltonians when the metric operator is explicitly time dependent. We demonstrate here that the time-dependent Dyson equation and the time-dependent quasi-Hermiticity relation can be solve…

[Phys. Rev. A 93, 042114] Published Wed Apr 20, 2016

]]>The Casimir free energy and pressure of thin metal films deposited on metallic plates are considered using the Lifshitz theory and the Drude and plasma model approaches to the role of conduction electrons. The bound electrons are taken into account by using the complete optical data of film and plat…

[Phys. Rev. A 93, 042508] Published Wed Apr 20, 2016

]]>We identify a systematic present in two-photon direct frequency comb spectroscopy (DFCS) which is a result of chirped laser pulses and is a manifestation of the first-order Doppler effect. We carefully analyze this systematic and propose methods for its mitigation within the context of our measureme…

[Phys. Rev. A 93, 042509] Published Wed Apr 20, 2016

]]>A theoretical method is presented for the estimation of cross sections and rates for excitation and charge-transfer processes in low-energy hydrogen-atom collisions with neutral atoms, based on an asymptotic two-electron model of ionic-covalent interactions in the neutral atom-hydrogen-atom system. …

[Phys. Rev. A 93, 042705] Published Wed Apr 20, 2016

]]>This paper generalizes the Siegert pseudostate (SPS) formulation of scattering theory to arbitrary finite-range potentials without any symmetry in the three-dimensional (3D) case. The orthogonality and completeness properties of 3D SPSs are established. The SPS expansions for scattering states, outg…

[Phys. Rev. A 93, 042706] Published Wed Apr 20, 2016

]]>Electric noise from metallic surfaces is a major obstacle towards quantum applications with trapped ions due to motional heating of the ions. Here, we discuss how the same noise source can also lead to pure dephasing of motional quantum states. The mechanism is particularly relevant at small ion-sur…

[Phys. Rev. A 93, 043415] Published Wed Apr 20, 2016

]]>The cutoff regime of high-order harmonic generation (HHG) by atoms in an intense laser field is studied numerically and analytically. We find that the cutoff regime is characterized by equal dephasing between the successive harmonics. The change of the harmonic phase locking when HHG evolves from th…

[Phys. Rev. A 93, 043416] Published Wed Apr 20, 2016

]]>Since the well-known $\mathcal{PT}$ symmetry has its fundamental significance and implication in physics, where $\mathcal{PT}$ denotes a joint operation of space inversion $\mathcal{P}$ and time reversal $\mathcal{T}$, it is important and intriguing to explore exotic $\mathcal{PT}$-invariant topological metals and to physically realize them. Here we develop …

[Phys. Rev. A 93, 043617] Published Wed Apr 20, 2016

]]>We investigate an optomechanical system which realizes the Jaynes-Cummings (JC) model known in cavity QED. Such a system consists of a single photon and an optomechanical cavity with two optical cavity modes and one mechanical mode. Under the resonance condition when the mechanical frequency is clos…

[Phys. Rev. A 93, 043834] Published Wed Apr 20, 2016

]]>We analyze the impact of delayed optical feedback (OF) on the spatiotemporal dynamics of the Lugiato-Lefever model. First, we carry out linear stability analysis and reveal the role of the OF strength and phase on the shape of the bistable curve as well as on Turing, Andronov-Hopf, and traveling-wav…

[Phys. Rev. A 93, 043835] Published Wed Apr 20, 2016

]]>It is known that any bipartite unitary operator of Schmidt rank 3 is equivalent to a controlled unitary under local unitaries. We propose a standard form of such operators. Using the form we improve the upper bound for the entanglement cost to implement such operators under local operations and clas…

[Phys. Rev. A 93, 042331] Published Tue Apr 19, 2016

]]>Recently introduced time-dependent renormalized-natural-orbital theory (TDRNOT) is extended towards a multicomponent approach in order to describe ${{\mathrm{H}}_{2}}^{+}$ beyond the Born-Oppenheimer approximation. Two kinds of natural orbitals, describing the electronic and the nuclear degrees of freedom are introduced…

[Phys. Rev. A 93, 043414] Published Tue Apr 19, 2016

]]>We show that, for ultracold neutral bosonic atoms held in a three-dimensional periodic potential or optical lattice, a Hubbard model with dominant, attractive three-body interactions can be generated. In fact, we derive that the effect of pairwise interactions can be made small or zero starting from…

[Phys. Rev. A 93, 043616] Published Tue Apr 19, 2016

]]>A new design for an optical frequency shifter combines a tunable filter and slow-light techniques.

[Phys. Rev. A 93, 043832] Published Tue Apr 19, 2016

]]>We explore theoretically the driven-dissipative physics of geometrically frustrated lattices of cavity resonators with relatively weak nonlinearities, i.e., a photon-photon interaction smaller than the loss rate. In such systems, photon modes with zero probability at dark sites are present at the si…

[Phys. Rev. A 93, 043833] Published Tue Apr 19, 2016

]]>By performing local projective measurements on a two-qubit entangled state one can certify in a device-independent way up to one bit of randomness. We show here that general measurements, defined by positive-operator-valued measures, can certify up to two bits of randomness, which is the optimal amo…

[Phys. Rev. A 93, 040102(R)] Published Mon Apr 18, 2016

]]>We investigate how the combination of nonequilibrium effects and material properties impacts on the Casimir-Polder interaction between an atom and a surface. By addressing systems with temperature inhomogeneities and laser interactions, we show that nonmonotonous energetic landscapes can be produced…

[Phys. Rev. A 93, 042111] Published Mon Apr 18, 2016

]]>Singly ionized lutetium has recently been suggested as a potential clock candidate. Here we report a joint experimental and theoretical investigation of ${\mathrm{Lu}}^{+}$. Measurements relevant to practical clock operation are made and compared to atomic structure calculations. Calculations of scalar and tensor p…

[Phys. Rev. A 93, 042112] Published Mon Apr 18, 2016

]]>The nonlocal properties of the $W$ states are investigated under particle loss. By removing all but two particles from an $N$-qubit $W$ state, the resulting two-qubit state is still entangled. Hence, the $W$ state has high persistency of entanglement. We ask an analogous question regarding the persistency o…

[Phys. Rev. A 93, 042113] Published Mon Apr 18, 2016

]]>The relatively low key rate seems to be the major barrier to its practical use for the decoy-state measurement-device-independent quantum key distribution (MDI-QKD). We present a four-intensity protocol for the decoy-state MDI-QKD that hugely raises the key rate, especially in the case in which the …

[Phys. Rev. A 93, 042324] Published Mon Apr 18, 2016

]]>Although quantum key distribution (QKD) is theoretically secure, there is a gap between the theory and practice. In fact, real-life QKD may *not* be secure because component devices in QKD systems may deviate from the theoretical models assumed in security proofs. To solve this problem, it is necessar…

[Phys. Rev. A 93, 042325] Published Mon Apr 18, 2016

]]>Catalytic coherence transformations allow the otherwise impossible state transformations using only incoherent operations with the aid of an auxiliary system with finite coherence that is not being consumed in any way. Here we find the necessary and sufficient conditions for the deterministic and st…

[Phys. Rev. A 93, 042326] Published Mon Apr 18, 2016

]]>Quantum gates in topological quantum computation are performed by braiding non-Abelian anyons. These braiding processes can presumably be performed with very low error rates. However, to make a topological quantum computation architecture truly scalable, even rare errors need to be corrected. Error …

[Phys. Rev. A 93, 042327] Published Mon Apr 18, 2016

]]>Device-independent quantum key distribution (DIQKD) guarantees unconditional security of a secret key without making assumptions about the internal workings of the devices used for distribution. It does so using the loophole-free violation of a Bell's inequality. The primary challenge in realizing D…

[Phys. Rev. A 93, 042328] Published Mon Apr 18, 2016

]]>We investigate a hybrid system of a superconducting charge qubit interacting directly with a single neutral atom via electric dipole coupling. Interfacing of the macroscopic superconducting circuit with the microscopic atomic system is accomplished by varying the gate capacitance of the charge qubit…

[Phys. Rev. A 93, 042329] Published Mon Apr 18, 2016

]]>We have explored the dipole-dipole mediated, resonant energy transfer reaction, $32{p}_{3/2}+32{p}_{3/2}\to 32s+33s$, in an ensemble of cold ${}^{85}\mathrm{Rb}$ Rydberg atoms. Stark tuning is employed to measure the population transfer probability as a function of the total electronic energy difference between the initial and fi…

[Phys. Rev. A 93, 042505] Published Mon Apr 18, 2016

]]>We present an interrogation scheme for the next generation of quantum clocks to suppress frequency shifts induced by laser probing fields that are themselves based on generalized hyper-Ramsey resonances. Sequences of composite laser pulses with a specific selection of phases, frequency detunings, an…

[Phys. Rev. A 93, 042506] Published Mon Apr 18, 2016

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