Performing entangling gates between physical qubits is necessary for building a large-scale universal quantum computer, but in some physical implementations—for example, those that are based on linear optics or networks of ion traps—entangling gates can only be implemented probabilistically. In this...

[Phys. Rev. A 97, 030301(R)] Published Fri Mar 16, 2018

]]>One of the most characteristic *mathematical * features of the $\mathcal{PT}$-symmetric quantum mechanics is the explicit Hamiltonian dependence of its physical Hilbert space of states $\mathcal{H}=\mathcal{H}\left(H\right)$. Some of the most important *physical * consequences are discussed, with emphasis on the dynamical regime in which the syste...

[Phys. Rev. A 97, 032114] Published Fri Mar 16, 2018

]]>Transitionless quantum driving, also known as counterdiabatic driving, is a unique shortcut technique to adiabaticity, enabling a fast-forward evolution to the same target quantum states as those in the adiabatic case. However, as nothing is free, the fast evolution is obtained at the cost of strong...

[Phys. Rev. A 97, 032115] Published Fri Mar 16, 2018

]]>We propose a scheme to realize high-precision quantum interferometry with entangled non-Gaussian states by driving the system through quantum phase transitions. The beam splitting, in which an initial nondegenerate ground state evolves into a highly entangled state, is achieved by adiabatically driv...

[Phys. Rev. A 97, 032116] Published Fri Mar 16, 2018

]]>We consider the evolution of the quantum states of a Hamiltonian that is parametrically perturbed via a term proportional to the adiabatic parameter $\lambda \left(t\right)$. Starting with the Pechukas-Yukawa mapping of the energy eigenvalue evolution in a generalized Calogero-Sutherland model of a one-dimensional clas...

[Phys. Rev. A 97, 032117] Published Fri Mar 16, 2018

]]>We study the classical and quantum rotation numbers of the free rotation of asymmetric-top molecules. We show numerically that the quantum rotation number converges to its classical analog in the semiclassical limit. Different asymmetric molecules such as the water molecule are taken as an illustrat...

[Phys. Rev. A 97, 032118] Published Fri Mar 16, 2018

]]>We provide a class of entanglement witnesses constructed in terms of mutually unbiased bases (MUBs). This construction reproduces many well-known examples such as the celebrated reduction map and the Choi map together with its generalizations. We illustrate our construction by a detailed analysis of...

[Phys. Rev. A 97, 032318] Published Fri Mar 16, 2018

]]>A recipe to construct bound entangled states, i.e., entangled in a way that cannot be distilled, is presented. Contrary to known previous examples, the proposed method leads to states with a simpler structure, considered as generalizations of the well-known $W$ states, which may, therefore, be more attractive for experimental investigations.

[Phys. Rev. A 97, 032319] Published Fri Mar 16, 2018

]]>We propose a method for the implementation of one-way quantum computing in superconducting circuits. Measurement-based quantum computing is a universal quantum computation paradigm in which an initial cluster state provides the quantum resource, while the iteration of sequential measurements and loc...

[Phys. Rev. A 97, 032320] Published Fri Mar 16, 2018

]]>We investigate the dissociation dynamics of diatomic molecules subjected to both a femtosecond infrared (IR) laser pulse and a femtosecond pulse train (FPT) within the framework of the Morse potential model. When the IR and FPT are phase delayed, we observe well-resolved oscillations in dissociation...

[Phys. Rev. A 97, 033406] Published Fri Mar 16, 2018

]]>We study the ground-state properties of a system of $N$ harmonically trapped bosons of mass $m$ interacting with two-body contact interactions, from small to large scattering lengths. This is accomplished in a hyperspherical coordinate system that is flexible enough to describe both the overall scale of...

[Phys. Rev. A 97, 033608] Published Fri Mar 16, 2018

]]>We study the nonequilibrium dynamics of a one-dimensional Bose gas trapped by a harmonic potential for a quench from zero to infinite interaction. The different thermodynamic limits required for the equilibrium pre- and post-quench Hamiltonians are the origin of a few unexpected phenomena that have ...

[Phys. Rev. A 97, 033609] Published Fri Mar 16, 2018

]]>In a recent proposal [Jie and Zhang, Phys. Rev. A **95**, 060701(R) (2017)], it has been shown that center-of-mass-momentum-dependent two-body interactions can be generated and tuned by Raman coupling the closed-channel bound states in a magnetic Feshbach resonance. Here we investigate the universal rel...

[Phys. Rev. A 97, 033610] Published Fri Mar 16, 2018

]]>We compute the Tan's contact of a weakly interacting Bose gas at zero temperature in a cigar-shaped configuration. Using an effective one-dimensional Gross-Pitaevskii equation and Bogoliubov theory, we derive an analytical formula that interpolates between the three-dimensional and the one-dimension...

[Phys. Rev. A 97, 033611] Published Fri Mar 16, 2018

]]>Duan-Lukin-Cirac-Zoller quantum repeater protocol, which was proposed to realize long distance quantum communication, requires usage of quantum memories. Atomic ensembles interacting with optical beams based on off-resonant Raman scattering serve as convenient on-demand quantum memories. Here, a com...

[Phys. Rev. A 97, 033826] Published Fri Mar 16, 2018

]]>We obtained the phase and intensity images of an object by detecting classical light which never interacted with it. With a double passage of a pump and a signal laser beams through a nonlinear crystal, we observe interference between the two idler beams produced by stimulated parametric down conver...

[Phys. Rev. A 97, 033827] Published Fri Mar 16, 2018

]]>We present evidence of metastable rare quantum-fluctuation switching for the driven dissipative Jaynes-Cummings oscillator coupled to a zero-temperature bath in the strongly dispersive regime. We show that single-atom complex amplitude bistability is accompanied by the appearance of a low-amplitude ...

[Phys. Rev. A 97, 033828] Published Fri Mar 16, 2018

]]>We study the enhancement of cooperativity in the atom-light interface near a nanophotonic waveguide for application to quantum nondemolition (QND) measurement of atomic spins. Here the cooperativity per atom is determined by the ratio between the measurement strength and the decoherence rate. Counte...

[Phys. Rev. A 97, 033829] Published Fri Mar 16, 2018

]]>Strong quantum nonlinearity gives rise to many interesting quantum effects and has wide applications in quantum physics. Here we investigate the quantum nonlinear effect of an optomechanical system (OMS) consisting of both linear and quadratic coupling. Interestingly, a controllable optomechanical n...

[Phys. Rev. A 97, 033830] Published Fri Mar 16, 2018

]]>Dual-comb spectroscopy (DCS) utilizes two phase-locked optical frequency combs to allow scanless acquisition of spectra using only a single point detector. Although recent DCS measurements demonstrate rapid acquisition of absolutely calibrated spectral lines with unprecedented precision and accuracy...

[Phys. Rev. A 97, 033831] Published Fri Mar 16, 2018

]]>Knowing and controlling the spatial polarization distribution of a beam is of importance in applications such as optical tweezing, imaging, material processing, and communications. Here we show how the polarization distribution is affected by both linear and nonlinear (self-focusing) propagation. We...

[Phys. Rev. A 97, 033832] Published Fri Mar 16, 2018

]]>According to quantum mechanics, if we keep observing a continuous variable we generally disturb its evolution. For a class of observables, however, it is possible to implement a so-called quantum nondemolition measurement: by confining the perturbation to the conjugate variable, the observable is es...

[Phys. Rev. A 97, 033833] Published Fri Mar 16, 2018

]]>We consider $E$-polarized bound states in the radiation continuum (BICs) in circular periodical arrays of $N$ infinitely long dielectric rods. We find that each true BIC which occurs in an infinite linear array has its counterpart in the circular array as a near-BIC with extremely large quality factor. ...

[Phys. Rev. A 97, 033834] Published Fri Mar 16, 2018

]]>A chirped laser pulse focused by a chromatic lens exhibits a dynamic, or flying, focus in which the trajectory of the peak intensity decouples from the group velocity. In a medium, the flying focus can trigger an ionization front that follows this trajectory. By adjusting the chirp, the ionization f...

[Phys. Rev. A 97, 033835] Published Fri Mar 16, 2018

]]>The computability of the quantifier of a given quantum resource is the essential challenge in the resource theory and the inevitable bottleneck for its application. Here we focus on the measurement-induced nonlocality and present a redefinition in terms of the skew information subject to a broken ob...

[Phys. Rev. A 97, 032112] Published Thu Mar 15, 2018

]]>We investigate quantum steering of an open quantum system by measurements on its environment in the framework of collision models. As an example we consider a coherently driven qubit dissipatively coupled to a bath. We construct local nonadaptive and adaptive as well as nonlocal measurement scenario...

[Phys. Rev. A 97, 032113] Published Thu Mar 15, 2018

]]>We address binary phase-shift-keyed communication channels based on Gaussian states and prove that squeezing improves state discrimination at fixed energy of the channel, and also in the presence of phase diffusion. We then assess performances of homodyne detection against the ultimate quantum limit...

[Phys. Rev. A 97, 032315] Published Thu Mar 15, 2018

]]>Quantum devices, from simple fixed-function tools to the ultimate goal of a universal quantum computer, will require high-quality, frequent repetition of a small set of core operations, such as the preparation of entangled states. These tasks are perfectly suited to realization by a coprocessor or s...

[Phys. Rev. A 97, 032316] Published Thu Mar 15, 2018

]]>We develop a family of perfect quantum error correcting codes that correct for phase errors that arise on any qubit, at any time, during a perfect state transfer experiment. These ensure that we find the optimal operating regime for corrected state transfer. For a specific class of system, we furthe...

[Phys. Rev. A 97, 032317] Published Thu Mar 15, 2018

]]>We measure the modification of the transmission spectra of cold ${}^{87}\mathrm{Rb}$ atoms in the proximity of an optical nanofiber (ONF). Van der Waals interactions between the atoms an the ONF surface decrease the resonance frequency of atoms closer to the surface. An asymmetric spectra of the atoms holds informa...

[Phys. Rev. A 97, 032509] Published Thu Mar 15, 2018

]]>$\mathcal{PT}$-symmetric quantum mechanics allows finding stationary states in mean-field systems with balanced gain and loss of particles. In this work we apply this method to rotating Bose-Einstein condensates with contact interaction which are known to support ground states with vortices. Due to the particle...

[Phys. Rev. A 97, 033607] Published Thu Mar 15, 2018

]]>We demonstrate that a Kalman filter applied to estimate the position of an optically levitated nanoparticle, and operated in real-time within a field programmable gate array, is sufficient to perform closed-loop parametric feedback cooling of the center-of-mass motion to sub-Kelvin temperatures. The...

[Phys. Rev. A 97, 033822] Published Thu Mar 15, 2018

]]>Quantum systems are affected by interactions with their environments, causing decoherence through two processes: pure dephasing and energy relaxation. For quantum information processing it is important to increase the coherence time of Josephson qubits and other artificial two-level atoms. We show t...

[Phys. Rev. A 97, 033823] Published Thu Mar 15, 2018

]]>We propose an approach based on a local Hilbert transform to design non-Hermitian potentials generating arbitrary vector fields of directionality, $\stackrel{\u20d7}{p}\left(\stackrel{\u20d7}{r}\right)$, with desired shapes and topologies. We derive a local Hilbert transform to systematically build such potentials by modifying background potential...

[Phys. Rev. A 97, 033824] Published Thu Mar 15, 2018

]]>We present and analyze a protocol in which polaritons in a noncoplanar optical cavity form fractional quantum Hall states. We model the formation of these states and present techniques for subsequently creating anyons and measuring their fractional exchange statistics. In this protocol, we use a rap...

[Phys. Rev. A 97, 033825] Published Thu Mar 15, 2018

]]>In an interesting article [Phys. Rev. A **81**, 052341 (2010)], Das and Agarwal have discussed the preservation of bipartite entanglement in three-level atoms employing the coherences induced by spontaneous emission. The authors considered various initially entangled qubits prepared from two $\mathsf{V}$-type thre...

[Phys. Rev. A 97, 036301] Published Thu Mar 15, 2018

]]>In a recent Comment Nair and Arun, Phys. Rev. A **97**, 036301 (2018), it was concluded that the two-qubit entanglement protection reported in our work [Das and Agarwal, Phys. Rev. A **81**, 052341 (2010)] is erroneous. While we acknowledge the error in analytical results on concurrence when dipole matrix e...

[Phys. Rev. A 97, 036302] Published Thu Mar 15, 2018

]]>Quantum theory does not provide a unique definition for the joint probability of two noncommuting observables, which is the next important question after the Born's probability for a single observable. Instead, various definitions were suggested, e.g., via quasiprobabilities or via hidden-variable t...

[Phys. Rev. A 97, 030102(R)] Published Wed Mar 14, 2018

]]>Theories with indefinite causal structure have been studied from both the fundamental perspective of quantum gravity and the practical perspective of information processing. In this paper we point out a restriction in forming tensor products of objects with indefinite causal structure in certain mod...

[Phys. Rev. A 97, 032110] Published Wed Mar 14, 2018

]]>We present a technique to coarse grain quantum states in a finite-dimensional Hilbert space. Our method is distinguished from other approaches by not relying on structures such as a preferred factorization of Hilbert space or a preferred set of operators (local or otherwise) in an associated algebra...

[Phys. Rev. A 97, 032111] Published Wed Mar 14, 2018

]]>The lifetime of the long-lived $5d{\phantom{\rule{0.16em}{0ex}}}^{2}{D}_{5/2}$ level in ${}^{138}\mathrm{Ba}^{+}$ ions was measured in trapped single ions and small ion crystals using continuous quantum jump spectroscopy. We find ${\tau}_{{D}_{5/2}}=25.6\left(0.5\right)\phantom{\rule{0.28em}{0ex}}\text{s}$, significantly below previously reported values. We have verified our result by exploiting camera images of the ...

[Phys. Rev. A 97, 032508] Published Wed Mar 14, 2018

]]>The development of quantum technologies which use quantum states of the light field interacting with other systems creates a demand for such states over wide frequency ranges. In this work we compare the bipartite entanglement and Einstein-Podolsky-Rosen (EPR) -steering properties of the two differe...

[Phys. Rev. A 97, 033820] Published Wed Mar 14, 2018

]]>We report on the observation of subharmonic resonances in high-order wave mixing associated with the quantized vibrational levels of atoms trapped in a one-dimensional optical lattice created by two intense nearly counterpropagating coupling beams. These subharmonic resonances, occurring at $\pm 1/2$ and...

[Phys. Rev. A 97, 033821] Published Wed Mar 14, 2018

]]>[Phys. Rev. A 97, 039904] Published Wed Mar 14, 2018

]]>The effects of Lorentz boosts on the quantum entanglement encoded by a pair of massive spin-$\frac{1}{2}$ particles are described according to the Lorentz covariant structure described by Dirac bispinors. The quantum system considered incorporates four degrees of freedom: two of them related to the bispinor in...

[Phys. Rev. A 97, 032106] Published Tue Mar 13, 2018

]]>Quantum steering is one form of quantum correlations interpolating between entanglement and Bell nonlocality, which in some cases can be detected by various steering inequalities. Recently, a remarkable and useful steerability criterion via geometric Bell-like inequalities was established [M. Zukows...

[Phys. Rev. A 97, 032107] Published Tue Mar 13, 2018

]]>There are heuristic arguments proposing that the accuracy of monitoring position of a free mass $m$ is limited by the standard quantum limit (SQL): ${\sigma}^{2}(X\left(t\right))\ge {\sigma}^{2}(X\left(0\right))+({t}^{2}/{m}^{2}){\sigma}^{2}(P\left(0\right))\ge \hslash t/m$, where ${\sigma}^{2}(X\left(t\right))$ and ${\sigma}^{2}(P\left(t\right))$ denote variances of the Heisenberg representation position and momentum operators. Yue...

[Phys. Rev. A 97, 032108] Published Tue Mar 13, 2018

]]>We investigate the dynamical properties for non-Hermitian triple-well systems with a loss in the middle well. When chemical potentials in the two end wells are uniform and nonlinear interactions are neglected, there always exists a dark state whose eigenenergy becomes zero and the projections onto w...

[Phys. Rev. A 97, 032109] Published Tue Mar 13, 2018

]]>In all practical communication channels, the code word consists of Gaussian states and the measurement strategy is often a Gaussian detector such as homodyning or heterodyning. We investigate the communication performance using a phase-conjugated alphabet and joint Gaussian detection in a phase-inse...

[Phys. Rev. A 97, 032313] Published Tue Mar 13, 2018

]]>The use of optical nonlinearities to implement quantum logical gates at the single-photon level is analytically investigated. A thorough discussion on why previous no-go arguments may not hold is presented.

[Phys. Rev. A 97, 032314] Published Tue Mar 13, 2018

]]>We examine the lateral Casimir-Polder force acting on a circular rotating emitter near a dielectric plane surface. As the circular motion breaks time-reversal symmetry, the spontaneous emission in a direction parallel to the surface is in general anisotropic. We show that a lateral force arises whic...

[Phys. Rev. A 97, 032507] Published Tue Mar 13, 2018

]]>We investigate multiparticle excitation effect on a collective density excitation as well as a single-particle excitation in a weakly interacting Bose-Einstein condensate (BEC). We find that although the weakly interacting BEC offers weak multiparticle excitation spectrum at low temperatures, this m...

[Phys. Rev. A 97, 033606] Published Tue Mar 13, 2018

]]>We study the fluorescence spectrum of a strongly driven two-level system (TLS) with modulated transition frequency, which is a bichromatically driven TLS and has multiple resonance frequencies. We are aiming to provide a reliable description of the fluorescence in a regime that is difficult to tackl...

[Phys. Rev. A 97, 033817] Published Tue Mar 13, 2018

]]>We demonstrate an adiabatic wavelength redshift using dynamic carrier depletion. Free carriers are first induced through two-photon absorption of a control pulse and then extracted by a reverse-biased *p-i-n* diode formed on a Si photonic crystal waveguide, resulting in rapid carrier depletion. A copr...

[Phys. Rev. A 97, 033818] Published Tue Mar 13, 2018

]]>We propose and analyze an efficient scheme for the lopsided Raman-Nath diffraction of one-dimensional ($1\mathrm{D}$) and two-dimensional ($2\mathrm{D}$) atomic gratings with periodic parity-time ($\mathcal{PT}$)-symmetric refractive index. The atomic grating is constructed by the cold-atomic vapor with two isotopes of rubidium, whi...

[Phys. Rev. A 97, 033819] Published Tue Mar 13, 2018

]]>In a seminal paper [Phys. Rev. D **27**, 2885 (1983)], Page and Wootters suggest that time evolution could be described solely in terms of correlations between systems and clocks, as a means of dealing with the “problem of time” stemming from vanishing Hamiltonian dynamics in many theories of quantum gr...

[Phys. Rev. A 97, 030101(R)] Published Mon Mar 12, 2018

]]>We investigate the ground-state properties of a dual-species spin-1/2 Bose-Einstein condensate. One of the species is subjected to a pair of Raman laser beams that induces spin-orbit (SO) coupling, whereas the other species is not coupled to the Raman laser. In certain limits, analytical results can...

[Phys. Rev. A 97, 031601(R)] Published Mon Mar 12, 2018

]]>The dynamics of an electronic two-level system coupled to an electromagnetic field are simulated explicitly for one- and three-dimensional systems through semiclassical propagation of the Maxwell-Liouville equations. We consider three flavors of mixed quantum-classical dynamics: (i) the classical pa...

[Phys. Rev. A 97, 032105] Published Mon Mar 12, 2018

]]>The device-independent approach to physics is one where conclusions are drawn directly from the observed correlations between measurement outcomes. In quantum information, this approach allows one to make strong statements about the properties of the underlying systems or devices solely via the obse...

[Phys. Rev. A 97, 032309] Published Mon Mar 12, 2018

]]>The Barenco gate ($\mathbb{B}$) is a type of two-qubit quantum gate based on which alone universal quantum computation can be achieved. Each $\mathbb{B}$ is characterized by three angles ($\alpha $, $\theta $, and $\varphi $), though it works in a two-qubit Hilbert space. Here we design $\mathbb{B}$ via a noncollinear interaction $V|{r}_{1}{r}_{2}\rangle \langle {r}_{1}{r}_{3}|+\mathrm{H}.\mathrm{c}.$, where $...$

[Phys. Rev. A 97, 032310] Published Mon Mar 12, 2018

]]>We investigate the performance of several continuous-variable quantum key distribution protocols in the presence of uniform fading channels. These are lossy channels whose transmissivity changes according to a uniform probability distribution. We assume the worst-case scenario where an eavesdropper ...

[Phys. Rev. A 97, 032311] Published Mon Mar 12, 2018

]]>We introduce a family of quantum key distribution protocols for distributing shared random keys within a network of $n$ users. The advantage of these protocols is that any possible key structure needed within the network, including broadcast keys shared among subsets of users, can be implemented by us...

[Phys. Rev. A 97, 032312] Published Mon Mar 12, 2018

]]>Laser-induced electric quadrupole transition rates between hyperfine states of the rovibrational levels of the molecular ion H${}_{2}^{+}$ are calculated. These transitions are of metrological interest since they may be used for independent determination of fundamental constants such as particle-mass ratios and the Rydberg constant

[Phys. Rev. A 97, 032505] Published Mon Mar 12, 2018

]]>Multiconfiguration Hartree-Fock (MCHF) and multiconfiguration Dirac-Hartree-Fock (MCDHF) calculations are performed for the $2{p}^{5}\phantom{\rule{0.16em}{0ex}}{}^{2}P^{o}$, $2{p}^{4}{(}^{3}P)3s{\phantom{\rule{0.16em}{0ex}}}^{4}P$, $2{p}^{4}{(}^{3}P)3s{\phantom{\rule{0.16em}{0ex}}}^{2}P$, and $2{p}^{4}{(}^{3}P)3p{\phantom{\rule{0.16em}{0ex}}}^{4}{S}^{o}$ states of ${}^{19}\mathrm{F}$ i to determine their hyperfine constants. Several computing strategies are considered to investigate electron c...

[Phys. Rev. A 97, 032506] Published Mon Mar 12, 2018

]]>The unexpected emerging stability of a time-modulated magnetic guide, realized without external offset fields, is demonstrated. We found a steady periodic solution around which the nonlinear dynamics is linearized. To investigate the orbital stability of the guiding, a formal criterion based on the ...

[Phys. Rev. A 97, 033405] Published Mon Mar 12, 2018

]]>We show multiple electromechanically-induced transparency (EMIT) windows in a hybrid nano-electro-optomechanical system in the presence of two-level atoms coupled to a single-mode cavity field. The multiple EMIT-window profile can be observed by controlling the atom field coupling as well as Coulomb...

[Phys. Rev. A 97, 033812] Published Mon Mar 12, 2018

]]>Soliton crystals are periodic patterns of multispot optical fields formed from either time or space entanglements of equally separated identical high-intensity pulses. These specific nonlinear optical structures have gained interest in recent years with the advent and progress in nonlinear optical f...

[Phys. Rev. A 97, 033813] Published Mon Mar 12, 2018

]]>We theoretically investigate two-photon excitation by spectrally shaped entangled photons with energy anticorrelation in terms of how the real excitation of an intermediate state affects two-photon absorption by entangled photons. Spectral holes are introduced in the entangled photons around the ene...

[Phys. Rev. A 97, 033814] Published Mon Mar 12, 2018

]]>Attosecond electron pulses can be generated by crossing electrons with a laser beam at a membrane. A comprehensive experimental and theoretical investigation of this method is presented, offering a high-resolution tool to reveal the fundamental physics behind light-matter interaction.

[Phys. Rev. A 97, 033815] Published Mon Mar 12, 2018

]]>The excitation of toroidal multipoles in metamaterials is investigated for a high-$Q$ response at a subwavelength scale. In this paper, we explore the optimization of toroidal excitations in a planar metamaterial comprised of asymmetric split ring resonators (ASRRs). It is found that the scattering po...

[Phys. Rev. A 97, 033816] Published Mon Mar 12, 2018

]]>Using a purely quantum mechanical approach without trajectories, we are able to compute momentum-resolved ionization times of electrons released by the strong-field ionization of atoms. For the attoclock setting, we show that the dominant emission angle corresponds well to instantaneous ionization a...

[Phys. Rev. A 97, 031402(R)] Published Fri Mar 09, 2018

]]>Long-range macrodimers formed by $D$-state cesium Rydberg atoms are studied in experiments and calculations. Cesium ${\left[62{D}_{J}\right]}_{2}$ Rydberg-atom macrodimers, bonded via long-range multipole interaction, are prepared by two-color photoassociation in a cesium atom trap. The first color (pulse A) resonantly exci...

[Phys. Rev. A 97, 031403(R)] Published Fri Mar 09, 2018

]]>We analyze the lowest achievable temperature for a mechanical oscillator coupled with a quantum refrigerator composed of a parametrically driven system that is in contact with a bosonic reservoir where the energy is dumped. We show that the cooling of the oscillator (achieved by the resonant transpo...

[Phys. Rev. A 97, 032104] Published Fri Mar 09, 2018

]]>We introduce a quantum sensing protocol for detecting the parameters characterizing the phase-space displacement by using a single trapped ion as a quantum probe. We show that, thanks to the laser-induced coupling between the ion's internal states and the motion mode, the estimation of the two conju...

[Phys. Rev. A 97, 032308] Published Fri Mar 09, 2018

]]>We develop a nonclassicality criterion for the interference of three delayed, but otherwise identical, light fields in a three-mode Bell interferometer. We do so by comparing the prediction of quantum mechanics with those of a classical framework in which independent sources emit electric fields wit...

[Phys. Rev. A 97, 033809] Published Fri Mar 09, 2018

]]>We study the electromagnetic (EM) field in the shadow cast by a large opaque sphere. For this, we consider the scattering of a high-frequency monochromatic EM wave by the large sphere and develop a Mie theory that accounts for the presence of this obscuration. Applying fully absorbing boundary condi...

[Phys. Rev. A 97, 033810] Published Fri Mar 09, 2018

]]>Nanoscale pulsed light is highly desirable in nano-integrated optics. In this paper, we obtained femtosecond pulses with THz repetition frequency via the coupling between quantum emitters (QEs) and plasmonic resonators. Our structure consists of a $\mathsf{V}$-groove (VG) plasmonic resonator and a nanowire emb...

[Phys. Rev. A 97, 033811] Published Fri Mar 09, 2018

]]>[Phys. Rev. A 97, 039903] Published Fri Mar 09, 2018

]]>The preparation of molecules in well-defined internal states is essential for various studies in fundamental physics and physical chemistry. It is thus of particular interest to find methods that increase the brightness of molecular beams. Here, we report on rotational and vibrational pumpings of a ...

[Phys. Rev. A 97, 031401(R)] Published Thu Mar 08, 2018

]]>We establish uncertainty relations between information loss in general open quantum systems and the amount of nonergodicity of the corresponding dynamics. The relations hold for arbitrary quantum systems interacting with an arbitrary quantum environment. The elements of the uncertainty relations are...

[Phys. Rev. A 97, 032103] Published Thu Mar 08, 2018

]]>The metrological ability of carefully designed probes can be wrecked by the presence of noise which alters their evolution, reducing the information on the parameter of interest. This spoils the signal-to-noise ratio of any possible measurement. Here we show an experiment in which the introduction o...

[Phys. Rev. A 97, 032305] Published Thu Mar 08, 2018

]]>We present a general framework for the quantification and characterization of leakage errors that result when a quantum system is encoded in the subspace of a larger system. To do this we introduce metrics for quantifying the coherent and incoherent properties of the resulting errors and we illustra...

[Phys. Rev. A 97, 032306] Published Thu Mar 08, 2018

]]>In simple ferromagnetic quantum Ising models characterized by an effective double-well energy landscape the characteristic tunneling time of path-integral Monte Carlo (PIMC) simulations has been shown to scale as the incoherent quantum-tunneling time, i.e., as $1/{\mathrm{\Delta}}^{2}$, where $\mathrm{\Delta}$ is the tunneling gap. Sin...

[Phys. Rev. A 97, 032307] Published Thu Mar 08, 2018

]]>Atomic $M$-shell x-ray production cross sections induced by positrons near the threshold energy have been presented in this paper. In the experiment, online monitoring technology, which utilizes a high-purity germanium detector to record the annihilation photons emitted from the pure thick target impa...

[Phys. Rev. A 97, 032702] Published Thu Mar 08, 2018

]]>Inner-shell excitation during low-energy atomic collisions in the gas phase is driven by the formation of transient molecules, in which some electronic levels are promoted to higher energies. For collisions occurring in solids, it is commonly believed that electrons are promoted into the empty condu...

[Phys. Rev. A 97, 032703] Published Thu Mar 08, 2018

]]>We explore ways to use the ability to measure the populations of individual magnetic sublevels to improve the sensitivity of magnetic field measurements and measurements of atomic electric dipole moments (EDMs). When atoms are initialized in the $m=0$ magnetic sublevel, the shot-noise-limited uncertai...

[Phys. Rev. A 97, 033404] Published Thu Mar 08, 2018

]]>We analyze the finite-temperature phase diagram of the boson-fermion-Hubbard model with Feshbach converting interaction, using the coherent-state path-integral method. We show that depending on the position of the bosonic band, this type of interaction, even if weak, can drive the system into the re...

[Phys. Rev. A 97, 033605] Published Thu Mar 08, 2018

]]>We have studied multimode four-wave mixing (FWM) in an unresolved sideband cavity optomechanical system. The radiation pressure coupling between the cavity fields and multiple mechanical modes results in the formation of a series of tripod-type energy-level systems, which induce the multimode FWM ph...

[Phys. Rev. A 97, 033806] Published Thu Mar 08, 2018

]]>We predict the occurrence of single-photon-induced entanglement and quantum superposition in a hybrid quantum model, introducing an optomechanical coupling into the Rabi model. Originally, it comes from the photon-dependent quantum property of the ground state featured by the proposed hybrid model. ...

[Phys. Rev. A 97, 033807] Published Thu Mar 08, 2018

]]>We study the quantum correlations induced by spontaneous parametric down-conversion of a frequency comb. We derive a theoretical method to find the output state corresponding to a pump with an arbitrary spectral profile. After applying it to the relevant example of a spectrally chirped pump, we run ...

[Phys. Rev. A 97, 033808] Published Thu Mar 08, 2018

]]>[Phys. Rev. A 97, 039902] Published Thu Mar 08, 2018

]]>We discuss the disturbance by measurements which unambiguously discriminate between given candidate states. We prove that such an optimal measurement necessarily changes distinguishable states indistinguishable when the inconclusive outcome is obtained. The result was previously shown by Chefles [Ph...

[Phys. Rev. A 97, 032102] Published Wed Mar 07, 2018

]]>Given a coin with unknown bias $p\in [0,1]$, can we exactly simulate another coin with bias $f\left(p\right)$? The exact set of simulable functions has been well characterized 20 years ago. In this paper, we ask the quantum counterpart of this question: Given the quantum coin $|p\rangle =\sqrt{p}|0\rangle +\sqrt{1-p}|1\rangle $, can we exactly simulate ...

[Phys. Rev. A 97, 032303] Published Wed Mar 07, 2018

]]>We provide a quantification of the capability of various quantum dephasing processes to generate coherence out of incoherent states. The measures defined, admitting computable expressions for any finite Hilbert-space dimension, are based on probabilistic averages and arise naturally from the viewpoi...

[Phys. Rev. A 97, 032304] Published Wed Mar 07, 2018

]]>High-fidelity entangled Bell states are of great interest in quantum physics. Entanglement of ultracold neutral atoms in two spatially separated optical dipole traps is promising for implementation of quantum computing and quantum simulation and for investigation of Bell states of material objects. ...

[Phys. Rev. A 97, 032701] Published Wed Mar 07, 2018

]]>The temperature and interaction dependence of the first and second sound in a two-dimensional Bose gas is studied in the vicinity of the Berezinskii-Kosterlitz-Thouless transition, where it is found that the excitation of the second sound through a density perturbation becomes weaker as the interaction strength increases, as a consequence of the fast decrease of the thermal expansion coefficient.

[Phys. Rev. A 97, 033604] Published Wed Mar 07, 2018

]]>Traditionally, in macroscopic geometrical optics intrinsic polarization and spatial degrees of freedom of light can be treated independently. However, at the subwavelength scale these properties appear to be coupled together, giving rise to the spin-orbit interaction (SOI) of light. In this work we ...

[Phys. Rev. A 97, 033804] Published Wed Mar 07, 2018

]]>An evolution on the Bloch sphere is the fundamental state transition, including optical polarization controls and qubit operations. Conventional evolution of a polarization state or qubit is implemented within a closed system that automatically satisfies energy conservation from the Hermitian formal...

[Phys. Rev. A 97, 033805] Published Wed Mar 07, 2018

]]>We present a formalism based on first principles of quantum electrodynamics at nonzero temperature which permits us to calculate the Casimir-Polder interaction between an atom and a graphene sheet with arbitrary mass gap and chemical potential, including graphene-coated substrates. The free energy a...

[Phys. Rev. A 97, 032504] Published Tue Mar 06, 2018

]]>Polyatomic molecular ions contain many desirable attributes of a useful quantum system, including rich internal degrees of freedom and highly controllable coupling to the environment. To date, the vast majority of state-specific experimental work on molecular ions has concentrated on diatomic specie...

[Phys. Rev. A 97, 033403] Published Tue Mar 06, 2018

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