A noncommuting measurement transfers, via the apparatus, information encoded in a system's state to the external “observer.” Classical measurements determine properties of physical objects. In the quantum realm, the very same notion restricts the recording process to orthogonal states as only those …

[Phys. Rev. A 94, 022121] Published Fri Aug 26, 2016

]]>We operationally introduce mixed quantum $t$-designs as the most general arbitrary-rank extension of projective quantum $t$-designs which preserves indistinguishability from the uniform distribution for $t$ copies. First, we derive upper bounds on the classical communication capacity of any mixed $t$-design…

[Phys. Rev. A 94, 022335] Published Fri Aug 26, 2016

]]>We suggest a method for engineering a quantum walk, with cold atoms as walkers, which presents topologically nontrivial properties. We derive the phase diagram, and show that we are able to produce a boundary between topologically distinct phases using the finite beam width of the applied lasers. A …

[Phys. Rev. A 94, 023631] Published Fri Aug 26, 2016

]]>We investigate, theoretically and experimentally, the properties of Fibonacci lattices with arbitrary spacings. Different from periodic structures, the reciprocal lattice and the dynamical properties of Fibonacci lattices depend strongly on the lengths of their lattice parameters, even if the sequen…

[Phys. Rev. A 94, 023846] Published Fri Aug 26, 2016

]]>We demonstrate temporal chaos in a color-selection mechanism from the visible spectrum of a supercontinuum light source. The color-selection mechanism is governed by an acousto-optoelectronic nonlinear delayed-feedback scheme modeled by an Ikeda-like equation. Initially motivated by the design of a …

[Phys. Rev. A 94, 023847] Published Fri Aug 26, 2016

]]>The study of the decoherence of qubits in spin systems is almost restricted to environments whose constituents are spin-$\frac{1}{2}$ particles. In this paper we consider environments that are composed of particles of higher spin, and we investigate the consequences on the dynamics of a qubit coupled to such b…

[Phys. Rev. A 94, 022120] Published Thu Aug 25, 2016

]]>The expansion of the partition function for large coordination number $Z$ is a long-standing method and has formerly been used to describe the Ising model at finite temperatures. We extend this approach and study the interacting Bose gas at finite temperatures. An analytical expression for the free en…

[Phys. Rev. A 94, 023629] Published Thu Aug 25, 2016

]]>We study the many-body phases of bosonic atoms with $N$ internal states confined to a one-dimensional (1D) optical lattice under the influence of a synthetic magnetic field and strong repulsive interactions. The $N$ internal states of the atoms are coupled via Raman transitions creating the synthetic ma…

[Phys. Rev. A 94, 023630] Published Thu Aug 25, 2016

]]>Strong coupling between cavity photons and molecular vibrations can lead to the formation of vibron-polaritons. In a recent experiment with PVAc molecules in a metal-metal microcavity [Shalabney *et al.*, Angew. Chem., Int. Ed. **54**, 7971 (2015)], such a coupling was observed to enhance the Raman scatt…

[Phys. Rev. A 94, 023843] Published Thu Aug 25, 2016

]]>A scheme to reach the zero-point motion of an ion chain via optomechanical coupling is proposed. The ideas might aid the development of strategies for laser cooling bulk materials.

[Phys. Rev. A 94, 023844] Published Thu Aug 25, 2016

]]>We present a comprehensive analysis of the nonlinear optical Kerr effect in graphene. We directly solve the $S$-matrix element to calculate the absorption rate, utilizing the Volkov-Keldysh-type crystal wave functions. We then convert to the nonlinear refractive index coefficients through the Kramers-…

[Phys. Rev. A 94, 023845] Published Thu Aug 25, 2016

]]>We analyze the quantum evolution represented by a time-dependent family of generalized Pauli channels. This evolution is provided by the random decoherence channels with respect to the maximal number of mutually unbiased bases. We derive the necessary and sufficient conditions for the vanishing back…

[Phys. Rev. A 94, 022118] Published Wed Aug 24, 2016

]]>In this paper, we argue that quantum coherence in a bipartite system can be contained either locally or in the correlations between the subsystems. The portion of quantum coherence contained within correlations can be viewed as a kind of quantum correlation which we call correlated coherence. We dem…

[Phys. Rev. A 94, 022329] Published Wed Aug 24, 2016

]]>We propose force sensing protocols using a linear ion chain which can operate beyond the quantum standard limit. We show that oscillating forces that are off resonance with the motional trap frequency can be detected very efficiently by using quantum probes represented by various spin-boson models. …

[Phys. Rev. A 94, 022330] Published Wed Aug 24, 2016

]]>The implementation of holonomic quantum computation on superconducting quantum circuits is challenging due to the general requirement of controllable complicated coupling between multilevel systems. Here we solve this problem by proposing a scalable circuit QED lattice with simple realization of a u…

[Phys. Rev. A 94, 022331] Published Wed Aug 24, 2016

]]>One of the simplest methods for implementing quantum key distribution over fiber-optic communication is the Bennett-Brassard 1984 protocol with phase encoding (PE-BB84 protocol), in which the sender uses phase modulation over double pulses from a laser and the receiver uses a passive delayed interfe…

[Phys. Rev. A 94, 022332] Published Wed Aug 24, 2016

]]>Anonymous voting is a voting method of hiding the link between a vote and a voter, the context of which ranges from governmental elections to decision making in small groups like councils and companies. In this paper, we propose a quantum anonymous voting protocol assisted by two kinds of entangled …

[Phys. Rev. A 94, 022333] Published Wed Aug 24, 2016

]]>The theory of quantum state estimation is exploited here to investigate the most efficient strategies for this task, especially targeting a complete picture identifying optimal conditions in terms of Fisher information, quantum measurement, and associated estimator. The approach is specified to esti…

[Phys. Rev. A 94, 022334] Published Wed Aug 24, 2016

]]>We consider a narrow magneto-dipole transition in the ${}^{169}\text{Tm}$ atom at the wavelength of $1.14\mu \mathrm{m}$ as a candidate for a two-dimensional-optical lattice clock. Calculating dynamic polarizabilities of the two clock levels $\left[\text{Xe}\right]4{f}^{13}6{s}^{2}(J=7/2)$ and $\left[\text{Xe}\right]4{f}^{13}6{s}^{2}(J=5/2)$ in the spectral range from 250 to 1200 nm, …

[Phys. Rev. A 94, 022512] Published Wed Aug 24, 2016

]]>We theoretically investigate the electron dynamics in Ne atoms involving core-excited states through the Ramsey scheme with a pair of time-delayed x-ray pulses. Irradiation of Ne atoms by the $\sim 1$ femtosecond x-ray pulse simultaneously populates two core-excited states, and an identical but time-delay…

[Phys. Rev. A 94, 023417] Published Wed Aug 24, 2016

]]>Motivated by recent experiments, we study theoretically the dynamics of vortices in the crossover from two dimensions to one in atomic condensates in elongated traps. We explore the transition from the dynamics of a vortex to that of a dark soliton as the one-dimensional limit is approached, mapping…

[Phys. Rev. A 94, 023627] Published Wed Aug 24, 2016

]]>We study the spontaneous formation of defects in the order parameter of a trapped ultracold bosonic gas while crossing the critical temperature for Bose-Einstein condensation at different rates. The system has the shape of an elongated ellipsoid, whose transverse width can be varied. For slow enough…

[Phys. Rev. A 94, 023628] Published Wed Aug 24, 2016

]]>We theoretically show that the dipole force of an ensemble of quantum emitters embedded in a dielectric nanosphere can be exploited to achieve near-field optical levitation. The key ingredient is that the polarizability from the ensemble of embedded quantum emitters can be larger than the bulk polar…

[Phys. Rev. A 94, 023841] Published Wed Aug 24, 2016

]]>We study the emergence of a collective optical response of a cold and dense ${}^{87}\mathrm{Rb}$ atomic cloud to a near-resonant low-intensity light when the atom number is gradually increased. Experimental observations are compared with microscopic stochastic simulations of recurrent scattering processes between t…

[Phys. Rev. A 94, 023842] Published Wed Aug 24, 2016

]]>[Phys. Rev. A 94, 029907] Published Wed Aug 24, 2016

]]>The possibility of focusing light to an ever tighter spot has important implications for many applications and fields of optics research, such as nano-optics and plasmonics, laser-scanning microscopy, optical data storage, and many more. The size of lateral features of the field at the focus depends…

[Phys. Rev. A 94, 021803(R)] Published Tue Aug 23, 2016

]]>The boundary between classical and quantum correlations is well characterized by linear constraints called Bell inequalities. It is much harder to characterize the boundary of the quantum set itself in the space of no-signaling correlations. For the points on the quantum boundary that violate maxima…

[Phys. Rev. A 94, 022116] Published Tue Aug 23, 2016

]]>Quantum mechanics is in principle gauge invariant, but its interpretation could be gauge dependent. Some properties of the length-velocity gauge transformation are elucidated in this study about a two-photon transition process in atomic hydrogen.

[Phys. Rev. A 94, 022117] Published Tue Aug 23, 2016

]]>We investigate non-Hermitian Kitaev chains in which imaginary potentials are added to all or only the two end lattice sites to represent the physical gain and loss during their interacting processes with the environment. By analyzing the energy eigenvalues of the non-Hermitian Hamiltonians both anal…

[Phys. Rev. A 94, 022119] Published Tue Aug 23, 2016

]]>Digital signatures play an important role in software distribution, modern communication, and financial transactions, where it is important to detect forgery and tampering. Signatures are a cryptographic technique for validating the authenticity and integrity of messages, software, or digital docume…

[Phys. Rev. A 94, 022328] Published Tue Aug 23, 2016

]]>In this paper, we use the nonlinear generator of dynamics of the individual quantum trajectories of an optical cavity inside an instantaneous quantum feedback loop to measure the phase shift between two pathways of light with a precision above the standard quantum limit. The feedback laser provides …

[Phys. Rev. A 94, 023840] Published Tue Aug 23, 2016

]]>Binary quantum information can be fault-tolerantly encoded in states defined in infinite-dimensional Hilbert spaces. Such states define a computational basis, and permit a perfect equivalence between continuous and discrete universal operations. The drawback of this encoding is that the correspondin…

[Phys. Rev. A 94, 022325] Published Mon Aug 22, 2016

]]>We investigate the effect of variations in beam-splitter transmissions and path-length differences in the nonlinear sign gate that is used for linear optical quantum computing. We identify two implementations of the gate and show that the sensitivity to variations in their components differs signifi…

[Phys. Rev. A 94, 022326] Published Mon Aug 22, 2016

]]>Quantum annealing aims to exploit quantum mechanics to speed up the search for the solution to optimization problems. Most problems exhibit complete connectivity between the logical spin variables after they are mapped to the Ising spin Hamiltonian of quantum annealing. To account for hardware const…

[Phys. Rev. A 94, 022327] Published Mon Aug 22, 2016

]]>We report the development of quantum microscopic theory of quasiresonant dipole-dipole interaction in the ensembles of impurity atoms imbedded into transparent dielectric and located in a Fabry-Perot cavity. On the basis of the general approach we study the simultaneous influence of the cavity and r…

[Phys. Rev. A 94, 022511] Published Mon Aug 22, 2016

]]>The energy and time-of-flight distributions of water ionic fragments produced by impact of fast atoms and bare and dressed ions; namely, ${\mathrm{H}}^{+},{\mathrm{Li}}^{0\u20133+},{\mathrm{C}}^{1+}$, and ${\mathrm{C}}^{2+}$ are reported in this work. Fragment species as a function of emission energy and time-of-flight were recorded by using an electrostatic sp…

[Phys. Rev. A 94, 022712] Published Mon Aug 22, 2016

]]>We present theoretical photoelectron momentum distributions (PMDs) for ionization from Ar($3p$) and ${\mathrm{H}}_{2}{}^{+}$(${\sigma}_{g}$) orbitals by few-cycle, high-intensity, near-infrared laser fields circularly polarized in the $xy$ plane. The three-dimensional time-dependent Schrödinger equation is solved numerically within the…

[Phys. Rev. A 94, 023414] Published Mon Aug 22, 2016

]]>Helium atoms have been prepared in the circular $|n=55,\ell =54,{m}_{\ell}=+54\rangle $ Rydberg state using the crossed electric and magnetic fields method. The atoms, initially traveling in pulsed supersonic beams, were photoexcited from the metastable $1s2s\phantom{\rule{0.16em}{0ex}}{}^{3}S_{1}$ level to the outermost, ${m}_{\ell}=0$ Rydberg-Stark state with $n=55$ …

[Phys. Rev. A 94, 023415] Published Mon Aug 22, 2016

]]>We report our study of the optical pumping effect in absorption imaging of ${}^{23}\mathrm{Na}$ atoms in the $F=1$ hyperfine spin states. Solving a set of rate equations for the spin populations in the presence of a probe beam, we obtain an analytic expression for the optical signal of the $F=1$ absorption imaging. Fur…

[Phys. Rev. A 94, 023625] Published Mon Aug 22, 2016

]]>We simulate transport in an atomtronic circuit of a Bose-Einstein condensate that flows from a source region into a drain through a gate channel. The time-dependent Gross-Pitaevskii equation (GPE) solution matches the data of a recent experiment. The atomtronic circuit is found to be similar to a va…

[Phys. Rev. A 94, 023626] Published Mon Aug 22, 2016

]]>We investigate theoretically the response of the output field from an optomechanical system consisting of $N$ nearly degenerate mechanical resonators each coupled to a common cavity mode. When the cavity is driven simultaneously by a strong control field and a weak probe field and each mechanical reso…

[Phys. Rev. A 94, 023837] Published Mon Aug 22, 2016

]]>The use of phase plates in the back focal plane of a microscope is a well-established technique in optical microscopy to increase the contrast of weakly interacting samples and is gaining interest in electron microscopy as well. In this paper we study the spiral phase plate (SPP), also called helica…

[Phys. Rev. A 94, 023838] Published Mon Aug 22, 2016

]]>We discuss the optical-heterodyne-detection technique to study the absorption and dispersion of a probe beam propagating through a medium with a narrow resonance. The technique has been demonstrated for Rydberg electromagnetically induced transparency in rubidium thermal vapor and the optical nonlin…

[Phys. Rev. A 94, 023839] Published Mon Aug 22, 2016

]]>[Phys. Rev. A 94, 029906] Published Mon Aug 22, 2016

]]>We present an analytical method for calculating the spectral function and the density of states in speckle potentials, valid in the semiclassical regime. Our approach relies on stationary phase approximations, allowing us to describe the singular quantum corrections at low energies. We apply it to t…

[Phys. Rev. A 94, 022114] Published Fri Aug 19, 2016

]]>For a number of noninteracting identical particles entering a multichannel scatterer in various wave-packet states, we construct a generating function for the probabilities of various scattering outcomes. This is used to evaluate the mean numbers of particles, ${\overline{n}}_{m}$, scattered into a given $(m\mathrm{th})$ chann…

[Phys. Rev. A 94, 022115] Published Fri Aug 19, 2016

]]>We show that the quantification of entanglement of any rank-2 state with any polynomial entanglement measure can be recast as a geometric problem on the corresponding Bloch sphere. This approach provides insight into the properties of entanglement and allows us to relate different polynomial measure…

[Phys. Rev. A 94, 022324] Published Fri Aug 19, 2016

]]>We theoretically address grazing incidence fast atom diffraction (GIFAD) for H atoms impinging on a LiF(001) surface. Our model combines a description of the H-LiF(001) interaction obtained from density functional theory calculations with a semiquantum treatment of the dynamics. We analyze simulated…

[Phys. Rev. A 94, 022711] Published Fri Aug 19, 2016

]]>We show that it is possible to cool interacting pairs of atoms by a lin $\perp $ lin Sisyphus-like laser cooling scheme using counterpropagating photoassociation (PA) lasers. It is shown that the center-of-mass (c.m.) motion of atom pairs can be trapped in molecular spin-dependent periodic potentials gener…

[Phys. Rev. A 94, 023413] Published Fri Aug 19, 2016

]]>Nonlinear two-level Landau-Zener type equations for systems with relevance for Bose-Einstein condensates and nonlinear optics are considered and the minimal time ${T}_{\mathrm{min}}$ to drive an initial state to a given target state is investigated. Surprisingly, the nonlinearity may be canceled by a time-optimal u…

[Phys. Rev. A 94, 023624] Published Fri Aug 19, 2016

]]>A problem in quantum information theory is to find the experimental setup that maximizes the nonlocality of correlations with respect to some suitable measure such as the violation of Bell inequalities. There are however some complications with Bell inequalities. First and foremost it is unfeasible …

[Phys. Rev. A 94, 022322] Published Thu Aug 18, 2016

]]>We identify subsystem fluctuations (variances) that measure entanglement in an arbitrary bipartite pure state. These fluctuations are of observables that generalize the notion of polarization to an arbitrary $N$-level subsystem. We express this polarization fluctuation in terms of subsystem purity and…

[Phys. Rev. A 94, 022323] Published Thu Aug 18, 2016

]]>The noncontact (van der Waals) friction is an interesting physical effect, which has been the subject of controversial scientific discussion. The direct friction term due to the thermal fluctuations of the electromagnetic field leads to a friction force proportional to $1/{\mathcal{Z}}^{5}$ (where $\mathcal{Z}$ is the atom-wall…

[Phys. Rev. A 94, 022510] Published Thu Aug 18, 2016

]]>The chirped-pulse interaction in the adiabatic coupling regime induces cyclic permutations of the energy states of a three-level system in the $V$-type configuration, which process is known as the three-level chirped rapid adiabatic passage (RAP). Here we show that a spectral hole in a chirped pulse c…

[Phys. Rev. A 94, 023412] Published Thu Aug 18, 2016

]]>Eigenstates of Bose particles with repulsive contact interactions in one-dimensional space with periodic boundary conditions can be found with the help of the Bethe ansatz. The type II excitation spectrum identified by E. H. Lieb, reproduces the dispersion relation of dark solitons in the mean-field…

[Phys. Rev. A 94, 023623] Published Thu Aug 18, 2016

]]>A cross-Kerr interaction produces a phase shift on two modes of light proportional to the number of photons in both modes and is sometimes called cross-phase modulation. Cross-Kerr nonlinearities have many applications in classical and quantum nonlinear optics, including the possibility of a determi…

[Phys. Rev. A 94, 023833] Published Thu Aug 18, 2016

]]>We study the phase sensitivity in the conventional SU(2) and nonconventional SU(1,1) interferometers with a coherent and squeezed vacuum input state via quantum Cramer-Rao bound. We explicitly construct the detection scheme that gives the optimal phase sensitivity. For practical purposes, we show th…

[Phys. Rev. A 94, 023834] Published Thu Aug 18, 2016

]]>The Rabi model, a two-level atom coupled to a harmonic oscillator, can undergo a second-order quantum phase transition (QPT) [M.-J. Hwang *et al.*, Phys. Rev. Lett. **115**, 180404 (2015)]. Here we show that the Rabi QPT accompanies critical behavior in the higher-energy excited states, i.e., the excited-…

[Phys. Rev. A 94, 023835] Published Thu Aug 18, 2016

]]>Discovered in the 19th century, the Brewster effect is known to occur for transverse-magnetic waves in regular optical dielectrics; however, it is believed to arise for transverse-electric (TE) waves only in systems with magnetic responses, i.e., nonunity effective relative permeability. This paper …

[Phys. Rev. A 94, 023836] Published Thu Aug 18, 2016

]]>Multiqubit quantum gates are natural quantum operations derived from various decompositions of quantum evolutions. Recently, linear-depth quantum circuits were proposed for an arbitrary $n$-qubit Toffoli gate with ancillary qubits [M. Saeedi and M. Pedram, Phys. Rev. A **87**, 062318 (2013)]. Their circui…

[Phys. Rev. A 94, 026301] Published Thu Aug 18, 2016

]]>We derive sufficient conditions for the memory-kernel governing nonlocal master equation which guarantee a legitimate (completely positive and trace-preserving) dynamical map. It turns out that these conditions provide natural parametrizations of the dynamical map being a generalization of the Marko…

[Phys. Rev. A 94, 020103(R)] Published Wed Aug 17, 2016

]]>In this work we study a system that consists of $2M$ matter qubits that interact through a boson sampling circuit, i.e., an $M$-port interferometer, embedded in two different architectures. We prove that, under the conditions required to derive a master equation, the qubits evolve according to effective…

[Phys. Rev. A 94, 022319] Published Wed Aug 17, 2016

]]>We propose some protocols to implement various classes of bipartite unitary operations on two remote parties with the help of repeater nodes in-between. We also present a protocol to implement a single-qubit unitary with parameters determined by a remote party with the help of up to three repeater n…

[Phys. Rev. A 94, 022320] Published Wed Aug 17, 2016

]]>Randomness is an indispensable resource in modern science and information technology. Fortunately, an experimentally simple procedure exists to generate randomness with well-characterized devices: measuring a quantum system in a basis complementary to its preparation. Towards realizing this goal one…

[Phys. Rev. A 94, 022321] Published Wed Aug 17, 2016

]]>In this work we explore the validity of employing a modified version of the nonrelativistic structure code civ3 for heavy, highly charged systems, using Na-like tungsten as a simple benchmark. Consequently, we present radiative and subsequent collisional atomic data compared with corresponding resul…

[Phys. Rev. A 94, 022508] Published Wed Aug 17, 2016

]]>We study the shift of rotational levels of a diatomic polar molecule due to its van der Waals interaction with a gently curved dielectric surface at temperature $T$, and submicron separations. The molecule is assumed to be in its electronic and vibrational ground state, and the rotational degrees are …

[Phys. Rev. A 94, 022509] Published Wed Aug 17, 2016

]]>Total and differential cross sections for mutual neutralization in ${\mathrm{He}}^{+}$ and ${\mathrm{H}}^{-}$ collisions at low to intermediate (0.001 eV to 100 eV) are calculated *ab initio* and fully quantum mechanically. Atomic final-state distributions and isotope effects are investigated. The theoretical model includes dynamics…

[Phys. Rev. A 94, 022709] Published Wed Aug 17, 2016

]]>We propose a classical trajectory Monte Carlo method to describe two-center collisions with two active electrons. The approach is based on switching between standard four-body and three-body descriptions and it is therefore easy to implement. We demonstrate the reliability of the approach for fundam…

[Phys. Rev. A 94, 022710] Published Wed Aug 17, 2016

]]>Diffraction of matter waves is an important demonstration of the fact that objects in nature possess a mixture of particlelike and wavelike properties. Unlike in the case of light diffraction, matter waves are subject to a vacuum-mediated interaction with diffraction obstacles. Here we present a det…

[Phys. Rev. A 94, 023621] Published Wed Aug 17, 2016

]]>We analyze theoretically the quantization of conductance occurring with cold bosonic atoms trapped in two reservoirs connected by a constriction with an attractive gate potential. We focus on temperatures slightly above the condensation threshold in the reservoirs. We show that a conductance step oc…

[Phys. Rev. A 94, 023622] Published Wed Aug 17, 2016

]]>In this article, we consider an interesting class of optical and other systems in which the interaction or coupling makes the systems $\mathcal{PT}$ symmetric. We aim to compare their dynamical behaviors with that of the usual $\mathcal{PT}$-symmetric systems with intrinsic loss-gain terms. In particular, we focus on the i…

[Phys. Rev. A 94, 023829] Published Wed Aug 17, 2016

]]>Four standard quantum optics models, that is, the Rabi, Dicke, Jaynes-Cummings, and Tavis-Cummings models, were proposed by physicists many decades ago. Despite their relative simple forms and many previous theoretical works, their physics at a finite $N$, especially inside the superradiant regime, re…

[Phys. Rev. A 94, 023830] Published Wed Aug 17, 2016

]]>We present a hybrid optomechanical scheme to achieve dynamical squeezing of position quadrature of a mesoscopic mechanical oscillator, that can be externally controlled by classical fields. A membrane-in-the-middle setup is employed, in which an atom in $\mathrm{\Lambda}$ configuration is considered to be trapped on…

[Phys. Rev. A 94, 023831] Published Wed Aug 17, 2016

]]>We study Rydberg atoms modulated by strong radio-frequency (rf) fields with a frequency of 70 MHz. The Rydberg atoms are prepared in a room-temperature cesium cell, and their level structure is probed using electromagnetically induced transparency (EIT). As the rf field increases from the weak- into…

[Phys. Rev. A 94, 023832] Published Wed Aug 17, 2016

]]>Vortices and vortex arrays have been used as a hallmark of superfluidity in rotated, ultracold Fermi gases. These superfluids can be described in terms of an effective field theory for a macroscopic wave function representing the field of condensed pairs, analogous to the Ginzburg-Landau theory for …

[Phys. Rev. A 94, 023620] Published Tue Aug 16, 2016

]]>We demonstrate that for a passive optical cavity containing a dispersive atomic medium, the increase in scale factor near the critical anomalous dispersion is not canceled by mode broadening or attenuation, resulting in an overall increase in the predicted quantum-noise-limited sensitivity. Enhancem…

[Phys. Rev. A 94, 023828] Published Tue Aug 16, 2016

]]>Low-mass (sub-eV) spin-0 dark matter particles, which form a coherently oscillating classical field $\varphi ={\varphi}_{0}cos\left({m}_{\varphi}t\right)$, can induce oscillating variations in the fundamental constants through their interactions with the standard model sector. We calculate the effects of such possible interactions, which ma…

[Phys. Rev. A 94, 022111] Published Mon Aug 15, 2016

]]>We introduce a coherence susceptibility method, based on the fact that it signals quantum fluctuations, for identifying quantum phase transitions, which are induced by quantum fluctuations. This method requires no prior knowledge of order parameter, and there is no need for careful considerations co…

[Phys. Rev. A 94, 022112] Published Mon Aug 15, 2016

]]>Prior to a measurement in a quantum-state tomography experiment, it is important to evaluate the performance of this measurement with respect to the average accuracy in state estimation. We propose a fast and reliable numerical certification of measurement performance that is applicable to any known…

[Phys. Rev. A 94, 022113] Published Mon Aug 15, 2016

]]>We consider a generalized central spin model, consisting of two central qubits and an environmental spin chain (with periodic boundary condition) to which these central qubits are locally and weakly connected either at the same site or at two different sites separated by a distance $d$. Our purpose is…

[Phys. Rev. A 94, 022316] Published Mon Aug 15, 2016

]]>We present an algorithmic method for the digital quantum simulation of many-body locally indivisible non-Markovian open quantum systems. It consists of two parts: first, a Suzuki-Lie-Trotter decomposition of the global system propagator into the product of subsystem propagators, which may not be qua…

[Phys. Rev. A 94, 022317] Published Mon Aug 15, 2016

]]>In instantaneous nonlocal quantum computation, two parties cooperate in order to perform a quantum computation on their joint inputs, while being restricted to a *single* round of simultaneous communication. Previous results showed that instantaneous nonlocal quantum computation is possible, at the co…

[Phys. Rev. A 94, 022318] Published Mon Aug 15, 2016

]]>The exact values of the presently determined components of the angular Fock coefficients at the two-particle coalescences were obtained and systematized. The Green's-function approach was successfully applied to simplify the most complicated calculations. The boundary conditions for the Fock coeffic…

[Phys. Rev. A 94, 022506] Published Mon Aug 15, 2016

]]>We report the binding energy of ${}^{87}\mathrm{Rb}{}^{133}\mathrm{Cs}$ molecules in their rovibrational ground state measured using an offset-free optical frequency comb based on difference frequency generation technology. We create molecules in the absolute ground state using stimulated Raman adiabatic passage (STIRAP) with a …

[Phys. Rev. A 94, 022507] Published Mon Aug 15, 2016

]]>A statistical-type model is developed to describe the ion production and electron emission in collisions of (molecular) ions with atoms. The model is based on the Boltzmann population of the bound electronic energy levels of the quasimolecule formed in the collision and the discretized continuum. Th…

[Phys. Rev. A 94, 022707] Published Mon Aug 15, 2016

]]>Despite the fact that the first calculations of nuclear bremsstrahlung cross sections were performed for relativistic electrons more than 80 years ago by Sauter, Bethe and Heitler, and Racah, a fully satisfactory solution to this problem is still missing up to the present day. Numerical approaches a…

[Phys. Rev. A 94, 022708] Published Mon Aug 15, 2016

]]>We report a quantitative study of the effect of nonaxial recoil during Coulomb explosion of laser-aligned molecules and introduce a method to remove the blurring caused by nonaxial recoil in the fragment-ion angular distributions. Simulations show that nonaxial recoil affects correlations between th…

[Phys. Rev. A 94, 023410] Published Mon Aug 15, 2016

]]>A semiclassical model is developed to understand the electronic dynamics in the low-energy attosecond streaking. Under a relatively strong infrared (IR) pulse, the low-energy part of photoelectrons initialized by a single attosecond pulse (SAP) can either rescatter with the ionic core and induce int…

[Phys. Rev. A 94, 023411] Published Mon Aug 15, 2016

]]>We explore the asymmetric sequential Landau-Zener (LZ) dynamics in an ensemble of interacting Bose-condensed two-level atoms coupled with a cavity field. Assuming the couplings between all atoms and the cavity field are identical, the interplay between atom-atom interaction and detuning may lead to …

[Phys. Rev. A 94, 023618] Published Mon Aug 15, 2016

]]>We show that radio-frequency (rf) radiation may be used to create Feshbach resonances in ultracold gases of alkali-metal atoms at desired magnetic fields that are convenient for atomic cooling and degeneracy. For the case of ${}^{39}\mathrm{K}+{}^{133}\mathrm{Cs}$, where there are no rf-free resonances in regions where Cs may be…

[Phys. Rev. A 94, 023619] Published Mon Aug 15, 2016

]]>We propose a method for generating an optical Schrödinger-cat-like state in a cavity in a substantial decoherence regime. Even when the cavity decay rate is considerably large, a cat-like state can be generated in a laser-like setting if the gain for the field is larger than the loss. Under the cond…

[Phys. Rev. A 94, 023826] Published Mon Aug 15, 2016

]]>We theoretically study the high-order correlation functions of chaotic bosons and fermions. Based on the different parity of the Stirling number, the products of the first-order correlation functions are well classified and employed to represent the high-order correlation function. The correlation o…

[Phys. Rev. A 94, 023827] Published Mon Aug 15, 2016

]]>[Phys. Rev. A 94, 029905] Published Mon Aug 15, 2016

]]>A resource-efficient encryption scheme is experimentally demonstrated. As a proof-of-principle, a photo is transmitted over a lossy channel applying quantum data (un)locking and error correction.

[Phys. Rev. A 94, 020301(R)] Published Fri Aug 12, 2016

]]>We investigate duality in entanglement of a bipartite multiphoton system generated from a coherent state of light. The system can exhibit polarization entanglement if the two parts are distinguished by their parity, or parity entanglement if the parts are distinguished by polarization. It was shown …

[Phys. Rev. A 94, 022314] Published Fri Aug 12, 2016

]]>Classical security theory states that a message is safely transmitted if the length of the encryption key equals that of the message itself. Taking advantage of the quantum uncertainty principle, it is experimentally demonstrated how to beat this limit, reducing to an arbitrarily small amount the leak of information.

[Phys. Rev. A 94, 022315] Published Fri Aug 12, 2016

]]>Previous work developed a $K$-matrix formalism applicable to positive energies for the scattering between two $s$-wave interacting particles with two internal states, isotropic spin-orbit coupling and vanishing center-of-mass momentum [H. Duan, L. You, and B. Gao, Phys. Rev. A **87**, 052708 (2013).]. This …

[Phys. Rev. A 94, 022706] Published Fri Aug 12, 2016

]]>We classify the ground states and topological defects of two-component Bose-Einstein condensates under the effect of internal coherent Rabi coupling. We present numerical phase diagrams which show the boundaries between symmetry-breaking components and various vortex patterns (triangular, square, bo…

[Phys. Rev. A 94, 023616] Published Fri Aug 12, 2016

]]>We show numerically that a harmonically trapped and coherently Rabi-coupled three-component Bose-Einstein condensate can host unconventional vortex lattices in its rotating ground state. The discovered lattices incorporate square and zig-zag patterns, vortex dimers and chains, and doubly quantized v…

[Phys. Rev. A 94, 023617] Published Fri Aug 12, 2016

]]>A number of techniques have been developed to characterize the attosecond emission from high-order-harmonic sources. These techniques are broadly classified as *ex situ*, where the attosecond pulse train photoionizes a target gas in the presence of an infrared field, and *in situ*, where the measurement…

[Phys. Rev. A 94, 023825] Published Fri Aug 12, 2016

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