Using *ab initio* non-Born-Oppenheimer simulations, we demonstrate the amplification of XUV radiation in a high-harmonic-generation-type process using the example of the hydrogen molecular ion. A small fraction of the molecules is pumped to a dissociative excited state from which IR-assisted XUV ampli…

[Phys. Rev. A 93, 021402(R)] Published Thu Feb 04, 2016

]]>One longstanding difficult problem in quantum dissipative dynamics is to solve the spin-boson model in a non-Markovian regime where a tractable systematic master equation does not exist. The spin-boson model is particularly important due to its crucial applications in quantum noise control and manip…

[Phys. Rev. A 93, 022105] Published Thu Feb 04, 2016

]]>High-dimensional quantum entanglement is drawing attention because it enables us to perform quantum information tasks that are robust against noises. To test the nonlocality of entangled qudits, the Collins-Gisin-Linden-Massar-Popescu (CGLMP) inequality has been proposed and demonstrated using qudit…

[Phys. Rev. A 93, 022307] Published Thu Feb 04, 2016

]]>We consider a Dirac one-electron atom placed in a weak, static, uniform magnetic field. We show that, to the first order in the strength $B$ of the external field, the only electric multipole moments, which are induced by the perturbation in the atom, are those of an even order. Using the Sturmian exp…

[Phys. Rev. A 93, 022504] Published Thu Feb 04, 2016

]]>The lifetime of ultra-long-range strontium Rydberg molecules is measured in the low-lying vibrational states, where its resemblance to the lifetime of the parent Rydberg atoms demonstrates that a $p$-wave resonance, which is absent in the present case but prevalent in Rydberg molecules comprised of alkali-metal atoms, plays an important role in determining the lifetime of such molecules.

[Phys. Rev. A 93, 022702] Published Thu Feb 04, 2016

]]>We calculate and analyze Feshbach resonance spectra for ultracold $\mathrm{Yb}\left({}^{1}{S}_{0}\right)+\mathrm{Yb}\left({}^{3}{P}_{2}\right)$ collisions as a function of an interatomic potential scaling factor $\lambda $ and external magnetic field. We show that, at zero field, the resonances are distributed randomly in $\lambda $, but that signatures of quantum chaos emerge …

[Phys. Rev. A 93, 022703] Published Thu Feb 04, 2016

]]>In recent experiments bosonic [Atala *et al.*, Nat. Phys. **10**, 588 (2014); Stuhl *et al.*, Science **349**, 1514 (2015)] as well as fermionic ladders [Mancini *et al.* Science **349**, 1510 (2015)] with a uniform flux were studied and different interesting many-body states were observed. Motivated by these exp…

[Phys. Rev. A 93, 023608] Published Thu Feb 04, 2016

]]>Vortex lattices in rapidly rotating Bose-Einstein condensates lead to a periodic modulation of the superfluid density with a triangular symmetry. Here we show that this symmetry can be combined with an external perturbation in order to create superlattice structures with two or more periodicities. C…

[Phys. Rev. A 93, 023609] Published Thu Feb 04, 2016

]]>We develop a Gaussian state treatment that allows a transparent quantum description of the continuous, nondestructive imaging of and feedback on a Bose-Einstein condensate. We have previously demonstrated [A. C. J. Wade *et al.*, Phys. Rev. Lett. **115**, 060401 (2015)] that the measurement backaction of…

[Phys. Rev. A 93, 023610] Published Thu Feb 04, 2016

]]>We investigate the Rabi oscillation of an atom placed inside a quantum cavity where each mirror is formed by a chain of atoms trapped near a one-dimensional waveguide. This proposal was studied previously with the use of Markov approximation, where the delay due to the finite travel time of light be…

[Phys. Rev. A 93, 023808] Published Thu Feb 04, 2016

]]>We present a theoretical model for a Kerr-like interaction between two registers of a compound gradient echo memory (GEM). This type of interaction is known to generate cross-phase modulation (XPM) between optical fields, an effect that is limited by the typically small values of nonlinearities in c…

[Phys. Rev. A 93, 023809] Published Thu Feb 04, 2016

]]>We report the observation of quantum reflection from a narrow attractive potential using bright solitary matter waves formed from a ${}^{85}\mathrm{Rb}$ Bose-Einstein condensate. We create the attractive potential using a tightly focused, red-detuned laser beam, and observe reflection of up to 25% of the atoms, alo…

[Phys. Rev. A 93, 021604(R)] Published Wed Feb 03, 2016

]]>We consider the general problem of estimating an unknown control parameter of an open quantum system. We establish a direct relation between the evolution of both system and environment and the precision with which the parameter can be estimated. We show that when the open quantum system undergoes a…

[Phys. Rev. A 93, 022103] Published Wed Feb 03, 2016

]]>We present the amount of information, fidelity, and reversibility obtained by arbitrary quantum measurements on completely unknown states. These quantities are expressed as functions of the singular values of a measurement operator corresponding to the obtained outcome. As an example, we consider a …

[Phys. Rev. A 93, 022104] Published Wed Feb 03, 2016

]]>Here we study multiplayer linear games, a natural generalization of xor games to multiple outcomes. We generalize a recently proposed efficiently computable bound, in terms of the norm of a game matrix, on the quantum value of two-player games to linear games with $n$ players. As an example, we bound …

[Phys. Rev. A 93, 022305] Published Wed Feb 03, 2016

]]>We prove that the squared Rényi-$\alpha $ entanglement ($\mathrm{SR}\alpha \mathrm{E}$), which is the generalization of entanglement of formation, obeys a general monogamy inequality in an arbitrary $N$-qubit mixed state. Furthermore, for a class of Rényi-$\alpha $ entanglement, we prove that the monogamy relations of the $\mathrm{SR}\alpha \mathrm{E}$ have a hierarch…

[Phys. Rev. A 93, 022306] Published Wed Feb 03, 2016

]]>The tunneling ionization of an excited hydrogen atom by a static electric field $\mathbf{E}$ is investigated for the case where the initial electron has an orbital angular momentum $\mathbf{L}$ nonparallel to $\mathbf{E}$. The outgoing electron has a nonzero mean transverse velocity $\langle {\mathbf{v}}_{\mathrm{T}}\rangle $ in the direction of $\mathbf{E}\times \langle \mathbf{L}\rangle $. During this proce…

[Phys. Rev. A 93, 023403] Published Wed Feb 03, 2016

]]>We experimentally determine the equation of state of a laser-cooled gas. By employing the Lane-Emden formalism, widely used in astrophysics, we derive the equilibrium atomic profiles in large magneto-optical traps where the thermodynamic effects are cast in a polytropic equation of state. The effect…

[Phys. Rev. A 93, 023404] Published Wed Feb 03, 2016

]]>We theoretically investigate the generation of atom-light entanglement via Raman superradiance in an optical cavity, and show how this can be used to enhance the sensitivity of atom interferometry. We model a realistic optical cavity, and show that by careful temporal shaping of the optical local os…

[Phys. Rev. A 93, 023607] Published Wed Feb 03, 2016

]]>A concrete mixed-state model for quantum metrology is proposed. The scheme can achieve quantum-enhanced precision scaling with the size of the used atomic ensemble.

[Phys. Rev. A 93, 023805] Published Wed Feb 03, 2016

]]>The control of light transmission through a standing-wave Fabry-Pérot cavity containing atoms is theoretically and numerically investigated, when the cavity mode beam and an intersecting control beam are both close to specific atomic resonances. A four-level atomic system is considered and its inter…

[Phys. Rev. A 93, 023806] Published Wed Feb 03, 2016

]]>We propose a pump-probe signal, whereby the sample is excited by a classical pulse, and—after a variable time delay—probed by a photon from an entangled pair, which is finally detected in coincidence with its twin. This setup offers an improved time and frequency resolution compared to a classical p…

[Phys. Rev. A 93, 023807] Published Wed Feb 03, 2016

]]>Non-Markovian effects in the evolution of open quantum systems have recently attracted widespread interest, particularly in the context of assessing the efficiency of energy and charge transfer in nanoscale biomolecular networks and quantum technologies. With the aid of many-body simulation methods,…

[Phys. Rev. A 93, 020102(R)] Published Tue Feb 02, 2016

]]>We resolve the real-time dynamics of a purely dissipative $s=1/2$ quantum spin or, equivalently, hard-core boson model on a hypercubic $d$-dimensional lattice. The considered quantum dissipative process drives the system to a totally symmetric macroscopic superposition in each of the ${S}^{3}$ sectors. Differe…

[Phys. Rev. A 93, 021602(R)] Published Tue Feb 02, 2016

]]>We analyze the spin dynamics of an out-of-equilibrium large spin dipolar atomic Bose gas in an optical lattice. We observe a smooth crossover from a complex oscillatory behavior to an exponential behavior throughout the Mott-to-superfluid transition. While both of these regimes are well described by…

[Phys. Rev. A 93, 021603(R)] Published Tue Feb 02, 2016

]]>Both longitudinal and transverse relaxations exist in the practical environment. Their simultaneous eliminations are extremely demanding in real applications. Previous experimental work has focused mainly on the suppression of transverse relaxation. In this paper we investigate the performance of th…

[Phys. Rev. A 93, 022304] Published Tue Feb 02, 2016

]]>Photoemission spectroscopy is one of the most frequently used tools for characterizing the electronic structure of condensed matter systems. We discuss a scheme for simulating photoemission from finite systems based on time-dependent density-functional theory. It allows for the first-principles calc…

[Phys. Rev. A 93, 022502] Published Tue Feb 02, 2016

]]>We find very good agreement between our theoretically evaluated lifetimes of the $5d{\phantom{\rule{0.16em}{0ex}}}^{2}{D}_{3/2}$ and $5d{\phantom{\rule{0.16em}{0ex}}}^{2}{D}_{5/2}$ states of Cs with the experimental values reported by DiBerardino *et al.* [Phys. Rev. A **57**, 4204 (1998)], which were demonstrated to disagree with an earlier rigorous theoretical study [Safronova and …

[Phys. Rev. A 93, 022503] Published Tue Feb 02, 2016

]]>We explore the conditions for resolving high-order electronic recollisions in high-order-harmonic spectroscopy. We identify intrinsic phase mismatch and time-frequency uncertainty as the two fundamental limitations against the spectral distinguishability of these multiple rescatterings. Our numerica…

[Phys. Rev. A 93, 023402] Published Tue Feb 02, 2016

]]>We derive from first principles the momentum exchange between a photon and a quantum mirror upon reflection, by considering the boundary conditions imposed by the mirror surface on the photon wave equation. We show that the system generally ends up in an entangled state, unless the mirror position u…

[Phys. Rev. A 93, 023803] Published Tue Feb 02, 2016

]]>We observe strong collective coupling between an optical cavity and the forbidden spin singlet to triplet optical transition ${}^{1}S_{0}$ to ${}^{3}P_{1}$ in an ensemble of ${}^{88}\text{Sr}$. Despite the transition being 1000 times weaker than a typical dipole transition, we observe a well-resolved vacuum Rabi splitting. We use th…

[Phys. Rev. A 93, 023804] Published Tue Feb 02, 2016

]]>Quantum nonlocality is a counterintuitive phenomenon that lies beyond the purview of causal influences. Recently, Bell inequalities have been generalized to the case of quantum inputs, leading to a powerful family of semiquantum Bell inequalities that are capable of detecting any entangled state. He…

[Phys. Rev. A 93, 020101(R)] Published Mon Feb 01, 2016

]]>We have observed ${L}_{23}^{2}-{M}^{3}$ Auger decay in argon where a double vacancy is filled by two valence electrons and a single electron is ejected from the atom. A well-resolved spectrum of these two-to-one electron transitions is compared to the result of the second-order perturbation theory and its decay br…

[Phys. Rev. A 93, 021401(R)] Published Mon Feb 01, 2016

]]>For $N$ spin-polarized fermions with harmonic pair interactions in a one-dimensional trap an odd-even effect is found. The spectrum of the one-particle reduced density matrix of the system's ground state differs qualitatively for $N$ odd and $N$ even. This effect only occurs for strong attractive and repu…

[Phys. Rev. A 93, 021601(R)] Published Mon Feb 01, 2016

]]>We propose a scheme of the exact fast forwarding of standard quantum dynamics for a charged particle. The present idea allows the acceleration of both the amplitude and the phase of the wave function throughout the fast-forward time range and is distinct from that of Masuda and Nakamura [Proc. R. So…

[Phys. Rev. A 93, 022101] Published Mon Feb 01, 2016

]]>We suggest a simple method to engineer a tight-binding quantum network based on proper coupling to an auxiliary non-Hermitian cluster. In particular, it is shown that effective complex non-Hermitian hopping rates can be realized with only complex onsite energies in the network. Three applications of…

[Phys. Rev. A 93, 022102] Published Mon Feb 01, 2016

]]>We present a concept of non-Gaussian measurement composed of a non-Gaussian ancillary state, linear optics, and adaptive heterodyne measurement, and on the basis of this we also propose a simple scheme of implementing a quantum cubic gate on a traveling light beam. In analysis of the cubic gate in t…

[Phys. Rev. A 93, 022301] Published Mon Feb 01, 2016

]]>We present two complete maximally hyperentangled state analysis protocols for photons entangled in the polarization and spatial-mode degrees of freedom. The first protocol is a hyperentangled Bell state analysis scheme for two photons, and the second is a hyperentangled Greenberger-Horne-Zeilinger (…

[Phys. Rev. A 93, 022302] Published Mon Feb 01, 2016

]]>Among the most popular and well-studied quantum characterization, verification, and validation techniques is randomized benchmarking (RB), an important statistical tool used to characterize the performance of physical logic operations useful in quantum information processing. In this work we provide…

[Phys. Rev. A 93, 022303] Published Mon Feb 01, 2016

]]>Recent advances in theoretical calculations of ${\mathrm{H}}_{2}$ dissociation energies and ultra-accurate measurements of ${\mathrm{H}}_{2}$ transition frequencies give possibilities not only for testing QED and relativistic effects, but also for searching for physics beyond the standard model. In this paper we show that at the l…

[Phys. Rev. A 93, 022501] Published Mon Feb 01, 2016

]]>We present a time-dependent calculation of the velocity-dependent forces which act on an excited atomic dipole in relative motion with respect to ground state atoms of a different kind. Both its interaction with a single atom and with a dilute atomic plate are evaluated. In either case, the total fo…

[Phys. Rev. A 93, 022701] Published Mon Feb 01, 2016

]]>A procedure is suggested for using transient absorption spectroscopy above the ionization threshold to measure the polarization of the continuum induced by an intense optical pulse. In this way transient absorption measurement can be used to probe subfemtosecond intense field dynamics in atoms and m…

[Phys. Rev. A 93, 023401] Published Mon Feb 01, 2016

]]>We study the dynamics of two gray solitons in a Bose-Einstein condensate confined by a toroidal trap with a tight confinement in the radial direction. Gross-Pitaevskii simulations show that solitons can be long-living objects passing through many collisional processes. We have observed quite differe…

[Phys. Rev. A 93, 023601] Published Mon Feb 01, 2016

]]>Ultracold atomic Fermi gases have been a popular topic of research, with attention being paid recently to two-dimensional (2D) gases. In this work, we perform $T=0$ *ab initio* diffusion Monte Carlo calculations for a strongly interacting two-component Fermi gas confined to two dimensions. We first go o…

[Phys. Rev. A 93, 023602] Published Mon Feb 01, 2016

]]>We experimentally and numerically demonstrate deterministic creation and manipulation of a pair of oppositely charged singly quantized vortices in a highly oblate Bose-Einstein condensate (BEC). Two identical blue-detuned, focused Gaussian laser beams that pierce the BEC serve as repulsive obstacles…

[Phys. Rev. A 93, 023603] Published Mon Feb 01, 2016

]]>We numerically investigate an experimentally viable method for generating and manipulating on-demand several vortices in a highly oblate atomic Bose-Einstein condensate (BEC) in order to initialize complex vortex distributions for studies of vortex dynamics. The method utilizes moving laser beams to…

[Phys. Rev. A 93, 023604] Published Mon Feb 01, 2016

]]>The variance of a many-particle operator is a very sensitive probe of many-body correlations. In contrast to the expectation value of such operators which depends on the condensation fraction of the Bose-Einstein condensate (BEC), their variance depends on the absolute number of depleted particles. …

[Phys. Rev. A 93, 023605] Published Mon Feb 01, 2016

]]>We explore theoretically how to tune the dynamics of a quasi-one-dimensional harmonically trapped Bose-Einstein condensate (BEC) due to an additional red- and blue-detuned Hermite-Gaussian dimple trap (HGdT). To this end we study a BEC in a highly nonequilibrium state, which is not possible in a tra…

[Phys. Rev. A 93, 023606] Published Mon Feb 01, 2016

]]>The Artmann formula provides an accurate determination of the Goos-Hänchen lateral displacement in terms of the light wavelength, refractive index, and incidence angle. In the total reflection region, this formula is widely used in the literature and confirmed by experiments. Nevertheless, for incid…

[Phys. Rev. A 93, 023801] Published Mon Feb 01, 2016

]]>In this work we theoretically investigate a hybrid system of two optomechanically coupled resonators, which exhibits induced transparency. This is realized by coupling an optical ring resonator to a toroid. In the semiclassical analyses, the system displays bistabilities, isolated branches (isolas),…

[Phys. Rev. A 93, 023802] Published Mon Feb 01, 2016

]]>We derive the dynamical invariants for a general $N$-state quantum system described by a pseudo-Hermitian Hamiltonian. Explicit expressions are presented for two- and three-state systems, which are exemplified by explicit analytic solutions for constant couplings. In the two-state case, we derive non-…

[Phys. Rev. A 93, 012123] Published Fri Jan 29, 2016

]]>We prove the existence of (one-way) communication tasks with a subconstant versus superconstant asymptotic gap, which we call “doubly infinite,” between their quantum information and communication complexities. We do so by studying the exclusion game [C. Perry *et al.*, Phys. Rev. Lett. **115**, 030504 (…

[Phys. Rev. A 93, 012347] Published Fri Jan 29, 2016

]]>We develop a time-dependent theory to investigate electron dynamics and photoionization processes of diatomic molecules interacting with strong laser fields including electron-electron correlation effects. We combine the recently formulated time-dependent generalized-active-space configuration inter…

[Phys. Rev. A 93, 013426] Published Fri Jan 29, 2016

]]>We classify all possible fractional charge vortices of charge less than unity in spin-1 and spin-2 polar and cyclic Bose-Einstein condensates (BECs) with zero magnetization. Statics and dynamics of these vortices in quasi-two-dimensional spinor BECs are studied employing an accurate numerical soluti…

[Phys. Rev. A 93, 013630] Published Fri Jan 29, 2016

]]>A means for precise experimental characterization of the dielectric susceptibility of an atomic gas inside an optical cavity is important for the design and operation of quantum light-matter interfaces, particularly in the context of quantum information processing. Here we present a numerically opti…

[Phys. Rev. A 93, 013858] Published Fri Jan 29, 2016

]]>Precision measurements of Cs ionization energies are performed at the frontier of atomic and laser science by employing cutting-edge technologies such as ultracold atoms and frequency-comb-based laser calibration, with the value of the first ionization energy now determined with 100 times more accuracy than the best previous measurement.

[Phys. Rev. A 93, 013424] Published Thu Jan 28, 2016

]]>With the three-dimensional classical ensemble model, we revisited the recollision dynamics in strong-field nonsequential double ionization (NSDI) by linearly polarized laser pulses. Back analysis of the NSDI trajectories shows that a significant part of the double ionization events undergo a multipl…

[Phys. Rev. A 93, 013425] Published Thu Jan 28, 2016

]]>We study the dynamical instabilities of superfluid flows in the $S=1$ Bose-Hubbard model. The time evolution of each spin component in a condensate is calculated based on the dynamical Gutzwiller approximation for a wide range of interactions, from a weakly correlated regime to a strongly correlated r…

[Phys. Rev. A 93, 013628] Published Thu Jan 28, 2016

]]>We propose a simple model with spin and orbit angular momentum coupling in a spin-1 Bose-Einstein condensate, where three internal atomic states are Raman coupled by a pair of copropagating Laguerre-Gaussian beams. The resulting Raman transition imposes a transfer of orbital angular momentum between…

[Phys. Rev. A 93, 013629] Published Thu Jan 28, 2016

]]>We investigated the spatial distribution of quantum fluctuations in a squeezed vacuum field, generated via polarization self-rotation (PSR) interaction of an ensemble of Rb atoms and a strong near-resonant linearly polarized laser field. We found that the noise suppression is greatly effected by the…

[Phys. Rev. A 93, 013853] Published Thu Jan 28, 2016

]]>The thermal effects model of the anisotropic slab crystal was built based on the practical operation condition of the solid-state laser. A full analytical solution of the heat equation for an anisotropic cubic cross-section, solid-state crystal is presented. We can conclude that the analytical solut…

[Phys. Rev. A 93, 013854] Published Thu Jan 28, 2016

]]>We show that the Einstein-Laub formulation of electrodynamics is invalid since it yields a stress-energy-momentum (SEM) tensor that is not frame invariant. Two leading hypotheses for the kinetic formulation of electrodynamics (Chu and Einstein-Laub) are studied by use of the relativistic principle o…

[Phys. Rev. A 93, 013855] Published Thu Jan 28, 2016

]]>We study the effect of mode coupling on a single-photon device in which a dipole quantum emitter (DQE) is embedded in a bimodal whispering-gallery-mode cavity. A scatterer is used to induce mode coupling between counterclockwise and clockwise propagating light fields, which interact with the DQE. We…

[Phys. Rev. A 93, 013856] Published Thu Jan 28, 2016

]]>We report the cancellation of the cross-phase-modulation-instability (XPMI) gain over a large spectral window (which we term the XPMI band gap) in a highly birefringent photonic-crystal fiber with zero group birefringence. The XPMI ceases to occur when single-frequency pumping of orthogonally polari…

[Phys. Rev. A 93, 013857] Published Thu Jan 28, 2016

]]>The ability to transfer quantum information from one location to another with high probability is of central importance to quantum information science. Unfortunately, for the simplest system of a uniform chain (a spin chain or a particle in a one-dimensional lattice), the state transfer time grows e…

[Phys. Rev. A 93, 012343] Published Wed Jan 27, 2016

]]>We propose a no-go theorem by proving the impossibility of constructing a deterministic quantum circuit that iterates a unitary oracle by calling it only once. Different schemes are provided to bypass this result and to approximately realize the iteration. The optimal scheme is also studied. An inte…

[Phys. Rev. A 93, 012344] Published Wed Jan 27, 2016

]]>In the quantum adiabatic algorithm, as the adiabatic parameter $s\left(t\right)$ changes slowly from zero to one with finite rate, a transition to excited states inevitably occurs and this induces an intrinsic computational error. We show that this computational error depends not only on the total computation ti…

[Phys. Rev. A 93, 012345] Published Wed Jan 27, 2016

]]>A strategy based on Kerr nonlinearity is devised that allows one to perform many of the operations of a quantum-information processor at cryogenic temperatures, solving inefficiencies in the two-way communication between quantum and classical hardware. The approach is a promising route for processing information beyond the few-qubit regime on superconducting platforms.

[Phys. Rev. A 93, 012346] Published Wed Jan 27, 2016

]]>It has been known for more than 15 years that the differential cross section of electrons emitted from diatomic molecules during interaction with energetic charged particles oscillates as a function of electron momentum. The origin of the phenomenon is two-center interference, which naturally relate…

[Phys. Rev. A 93, 012713] Published Wed Jan 27, 2016

]]>We derive the large-particle-number limit of the Bethe equations for the ground state of the attractive one-dimensional Bose gas (Lieb-Liniger model) on a ring and solve it for arbitrary coupling. We show that the ground state of this system can be mapped to the large-$N$ saddle point of Euclidean Yan…

[Phys. Rev. A 93, 013627] Published Wed Jan 27, 2016

]]>We consider an ideal invisibility cloak which is illuminated by monochromatic light and which moves in vacuum at constant relativistic velocity with respect to the common inertial frame of light source and observer. We show that, in general, the moving cloak becomes detectable by image distortions a…

[Phys. Rev. A 93, 013850] Published Wed Jan 27, 2016

]]>Entangled atomic states, such as spin-squeezed states, represent a promising resource for a new generation of quantum sensors and atomic clocks. We demonstrate that optimal control techniques can be used to substantially enhance the degree of spin squeezing in strongly interacting many-body systems,…

[Phys. Rev. A 93, 013851] Published Wed Jan 27, 2016

]]>Using the model of parametric interaction based on the spatiospectral Schmidt modes and generalized parametric approximation, we analyze coherence and the mode structure of ultraintense twin beams generated in the regime with pump depletion. We show that the increase of spatial and spectral coherenc…

[Phys. Rev. A 93, 013852] Published Wed Jan 27, 2016

]]>Atom chips provide compact and robust platforms towards the implementation of practical quantum technologies. A quick and faithful preparation of arbitrary input states for these devices is crucial but represents a challenging experimental task. This is especially difficult when the dynamical evolut…

[Phys. Rev. A 93, 010304(R)] Published Tue Jan 26, 2016

]]>Adaptive data collection and analysis, where data are being fed back to update the measurement settings, can greatly increase speed, precision, and reliability of the characterization of quantum systems. However, decoherence tends to make adaptive characterization difficult. As an example, we consid…

[Phys. Rev. A 93, 012122] Published Tue Jan 26, 2016

]]>We present a theoretical analysis of different methods to synthesize entangled states of two quantum mechanical resonators. These methods are inspired by experimentally demonstrated interactions of superconducting resonators with artificial atoms, and offer efficient routes to generate nonclassical …

[Phys. Rev. A 93, 012342] Published Tue Jan 26, 2016

]]>We propose a generalization of the superconducting circuit simulation of the dynamical Casimir effect where we consider relativistically moving boundary conditions following different trajectories. We study the feasibility of the setup used in the past to simulate the dynamical Casimir effect to rep…

[Phys. Rev. A 93, 012519] Published Tue Jan 26, 2016

]]>Fast creation of a single vortex in BEC of alkali-metal atoms at a prescribed position and time is still challenging, even though various methods to create single and multiple vortices have been proposed and demonstrated. Topological vortex formation is advantageous in this respect over other method…

[Phys. Rev. A 93, 013626] Published Tue Jan 26, 2016

]]>Potoček and Ferenczi [Phys. Rev. A **92**, 023829 (2015)] provided an analysis of the experimental evidence obtained by Danan *et al.* [Phys. Rev. Lett. **111**, 240402 (2013)] for the surprising behavior of photons passing through an interferometer, in particular, motion on disconnected paths. Potoček and Fe…

[Phys. Rev. A 93, 017801] Published Tue Jan 26, 2016

]]>We give an analytic construction of a class of two-qubit gate pulse sequences that act on five of the six spin-$\frac{1}{2}$ particles used to encode a pair of exchange-only three-spin qubits. Within this class, the problem of gate construction reduces to that of finding a smaller sequence that acts on four sp…

[Phys. Rev. A 93, 010303(R)] Published Mon Jan 25, 2016

]]>In this Rapid Communication, we theoretically discuss a large Doppler shift in a signal slow-light pulse in a photonic-crystal waveguide by considering its reflection at a quasilight speed mirror. The mirror is formed by the photonic band-gap shift induced by the high nonlinearity of a control slow-…

[Phys. Rev. A 93, 011802(R)] Published Mon Jan 25, 2016

]]>By placing an atom into a cavity, the electromagnetic mode structure of the cavity is modified. In cavity QED, one manifestation of this phenomenon is the appearance of a gauge-dependent diamagnetic term, known as the ${A}^{2}$ contribution. Although in atomic cavity QED, the resulting modification in the …

[Phys. Rev. A 93, 012120] Published Mon Jan 25, 2016

]]>We investigate Landau-Zener processes modeled by a two-level quantum system, with its finite bias energy varied in time and in the presence of a single broadened cavity mode at zero temperature. By applying the hierarchy equation method to the Landau-Zener problem, we computationally study the survi…

[Phys. Rev. A 93, 012121] Published Mon Jan 25, 2016

]]>The structure of multipartite quantum states can be very complex. Here the authors analyze a pure entangled 3-qutrit system, and show that a given convertibility property is fulfilled by separable operations (SEP) but not by local operations and classical communications (LOCC), a result that was previously proved to hold true for mixed states only.

[Phys. Rev. A 93, 012339] Published Mon Jan 25, 2016

]]>The existence of higher-order entanglement in the stimulated and spontaneous Raman processes is established using the perturbative solutions of the Heisenberg equations of motion for various field modes that are obtained using the Sen-Mandal technique and a fully quantum mechanical Hamiltonian that …

[Phys. Rev. A 93, 012340] Published Mon Jan 25, 2016

]]>We construct an entanglement witness for many-qubit systems, based on symmetric two-body correlations with two measurement settings. This witness is able to detect the entanglement of some Dicke states for any number of particles and such detection exhibits some robustness against white noise and th…

[Phys. Rev. A 93, 012341] Published Mon Jan 25, 2016

]]>Relativistic two-photon decay rates of the $2{s}_{1/2}$ and $2{p}_{1/2}$ states towards the $1{s}_{1/2}$ ground state of hydrogenic atoms are calculated by using numerically exact energies and wave functions obtained from the Dirac equation with the Lagrange-mesh method. This approach is an approximate variational metho…

[Phys. Rev. A 93, 012517] Published Mon Jan 25, 2016

]]>The local spin dynamics of the electron is studied from the viewpoint of the electric dipole moment (EDM) of the electron in the framework of the quantum field theory. The improvements of the computational accuracy of the effective electric field $\left({\mathcal{E}}_{\mathrm{eff}}\right)$ for the EDM and the understanding of spin prec…

[Phys. Rev. A 93, 012518] Published Mon Jan 25, 2016

]]>We present fully differential cross-section ratios for electron-impact ionization of helium without excitation and with simultaneous excitation of the residual ion. The results are obtained from a nonperturbative close-coupling formalism, with the resulting equations being solved by a $B$-spline $R$-mat…

[Phys. Rev. A 93, 012712] Published Mon Jan 25, 2016

]]>We demonstrate the observation of quasiperiodic revivals out to 27 ps in an impulsively aligned asymmetric-top molecule, sulfur dioxide $\left({\mathrm{SO}}_{2}\right)$, at high sample temperature and density (295 K, 0.5 bar). We find that the asymmetric top exhibits a strong correlation between population alignment and popul…

[Phys. Rev. A 93, 013421] Published Mon Jan 25, 2016

]]>Using a time-dependent density-functional-theory (TDDFT) method, we calculated the high-harmonic generation (HHG) spectra of ${\mathrm{N}}_{2}$ in 800- and 1300-nm intense lasers. The calculations reproduce the experimentally observed minimum near 40 eV and the shift of the minimum due to interference of different …

[Phys. Rev. A 93, 013422] Published Mon Jan 25, 2016

]]>The exact velocity-gauge minimal-coupling Hamiltonian describing the laser-matter interaction is transformed into another form by means of a series of gauge transformations. The Hamiltonian corresponding to this point of view is valid for an arbitrary time- and space-dependent laser field, also know…

[Phys. Rev. A 93, 013423] Published Mon Jan 25, 2016

]]>We investigate the specific heat at constant volume ${C}_{V}$ in the Bardeen-Cooper-Schrieffer–Bose-Einstein-condensate (BCS-BEC)-crossover regime of an ultracold Fermi gas above the superfluid phase transition temperature ${T}_{\mathrm{c}}$. Within the framework of the strong-coupling theory developed by Nozières and Sch…

[Phys. Rev. A 93, 013621] Published Mon Jan 25, 2016

]]>We calculate how correlations in a Bose lattice gas grow during a finite-speed ramp from the Mott to the superfluid regime. We use an interacting doublon-holon model, applying a mean-field approach for implementing hard-core constraints between these degrees of freedom. Our solutions are valid in an…

[Phys. Rev. A 93, 013622] Published Mon Jan 25, 2016

]]>We study the concavity of the dispersion relation $q\mapsto {\omega}_{\mathbf{q}}$ of the bosonic excitations of a three-dimensional spin-$\frac{1}{2}$ unpolarized Fermi gas in the random-phase approximation. In the limit of small wave numbers $q$, we obtain analytically the spectrum up to order 5 in $q$. In the neighborhood of $q=0$, a change…

[Phys. Rev. A 93, 013623] Published Mon Jan 25, 2016

]]>Unlike the Coulomb potential that acts between all semiconductor carriers, the potential commonly used for BCS superconductors and cold-atom gases acts between different fermion species only, these species differing by their spin or hyperfine index. The coboson formalism we develop here evidences th…

[Phys. Rev. A 93, 013624] Published Mon Jan 25, 2016

]]>We show that a trapped-ion chain interacting with an optical spin-dependent force shows strong frustration effects due to the interplay between long range interactions and the dressing by optical phases. We consider a strong spin-phonon coupling regime and predict a quantum phase diagram with differ…

[Phys. Rev. A 93, 013625] Published Mon Jan 25, 2016

]]>The Stokes-Mueller polarimetry is generalized to include nonlinear optical processes such as second- and third-harmonic generation, sum- and difference-frequency generations with Kleinman symmetry. The overall algebraic form of the polarimetry is preserved, where the incoming and outgoing radiations…

[Phys. Rev. A 93, 013847] Published Mon Jan 25, 2016

]]>We propose that a pulsed quantum optomechanical system can be applied to the problem of quantum parameter estimation, which targets yielding a higher precision of parameter estimation utilizing quantum resources than using classical methods. Concentrating mainly on the quantum Fisher information wit…

[Phys. Rev. A 93, 013848] Published Mon Jan 25, 2016

]]>We study all-optical switches operating on a single four-level atom with the $N$-type transition configuration in a two-mode nanofiber cavity with a significant length (on the order of 20 mm) and a moderate finesse (on the order of 300) under the electromagnetically induced transparency (EIT) conditio…

[Phys. Rev. A 93, 013849] Published Mon Jan 25, 2016

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