We provide an algorithm for preparing the thermofield double (TFD) state of the Sachdev-Ye-Kitaev (SYK) model without the need for an auxiliary bath. Following previous work, the TFD can be cast as the approximate ground state of a Hamiltonian, ${H}_{\text{TFD}}$. Using variational quantum circuits, we propose an...

[Phys. Rev. A 104, 012427] Published Thu Jul 29, 2021

]]>We evaluate analytically the quantum discord for a large family of multiqubit states. It is interesting to note that the quantum discord of three qubits and five qubits is the same, as is the quantum discord of two qubits and six qubits. We discover that the quantum discord of this family of states ...

[Phys. Rev. A 104, 012428] Published Thu Jul 29, 2021

]]>The authors introduce a new quantum distribution network architecture enabling control of the propagation direction of an entangled state using linear-optical devices and phase shifters and offering reconfigurable connections between multiple quantum nodes.

[Phys. Rev. A 104, 012617] Published Thu Jul 29, 2021

]]>Nonadiabatic holonomic gates provide an effective means to perform high-speed and error-resilient manipulation of quantum states. It is practically important to realize nonadiabatic holonomic multiqubit controlled gates since multiqubit controlled gates are widely used in quantum information process...

[Phys. Rev. A 104, 012618] Published Thu Jul 29, 2021

]]>Nonstoquastic Hamiltonians are hard to simulate due to the sign problem in quantum Monte Carlo simulation. It is, however, unclear whether nonstoquasticity can lead to advantage in quantum annealing. Here we show that $YY$ interactions between the qubits make the adiabatic path during quantum annealin...

[Phys. Rev. A 104, 012619] Published Thu Jul 29, 2021

]]>We consider theoretically the process of two-electron one-photon (TEOP) transitions to the ground state with the emission of a single ${K}_{\alpha \alpha}$ photon in a He-like sequence of atomic ions: from boron to uranium. The corresponding transition probabilities and transition energies are calculated within the Q...

[Phys. Rev. A 104, 012818] Published Thu Jul 29, 2021

]]>In this study, we investigate the three-body recombination (TBR) rates on both sides of the interspecies $d$-wave Feshbach resonance in the ${}^{85}\mathrm{Rb}$ -${}^{87}\mathrm{Rb}-{}^{87}\mathrm{Rb}$ system using the $R$-matrix propagation method in the hyperspherical coordinate frame. Our calculations are based on the Lennard-Jones model potenti...

[Phys. Rev. A 104, 013317] Published Thu Jul 29, 2021

]]>We present an approach to engineer the photon correlations emerging from the interference between an input field and the field scattered by a single atom in free space. Nominally, the inefficient atom-light coupling causes the quantum correlations to be dominated by the input field alone. To overcom...

[Phys. Rev. A 104, 013724] Published Thu Jul 29, 2021

]]>Quantum walks are counterparts of classical random walks. They spread faster, which can be exploited in information processing tasks, and constitute a versatile simulation platform for many quantum systems. Yet, some of their properties can be emulated with classical light. This raises a question: w...

[Phys. Rev. A 104, 012220] Published Wed Jul 28, 2021

]]>The monogamy of entanglement means that entanglement cannot be freely shared. In 2014, Oliveira *et al.* [T. R. de Oliveira, M. F. Cornelio, and F. F. Fanchini, Phys. Rev. A **89**, 034303 (2014)] proposed a monogamy relation in the linear version and considered it in terms of entanglement of formation. H...

[Phys. Rev. A 104, 012426] Published Wed Jul 28, 2021

]]>We study the van der Waals (vdW) interaction between a polarizable particle and a grounded conducting corrugated surface. For sinusoidal corrugations, one knows that, under the action of the lateral vdW force, an isotropic particle is always attracted to the nearest corrugation peak, with such behav...

[Phys. Rev. A 104, 012816] Published Wed Jul 28, 2021

]]>An experimental procedure is reported, which provides the absolute triple differential cross sections (ATDCSs) for electron-impact ionization of large (bio)molecules. This type of measurements represents the most stringent tests for new or existing theoretical models. We will use this procedure to t...

[Phys. Rev. A 104, 012817] Published Wed Jul 28, 2021

]]>The authors study steady-state phonon occupation in electromagnetically-induced-transparency cooling by extending the analytical description to include the second-order contribution of the Lamb-Dicke parameter. The results could be helpful for guiding the ion cooling experiments by refining and optimizing the parameters.

[Phys. Rev. A 104, 013117] Published Wed Jul 28, 2021

]]>The propagation of light-induced thermo-reorientational solitary waves in nematic liquid crystals is studied using numerical solutions of the full governing equations and variational approximations. These thermo-reorientational solitary waves form as the nonlocal refractive index response to extraor...

[Phys. Rev. A 104, 013526] Published Wed Jul 28, 2021

]]>Intuition dictates that a very long, very thin cavity (e.g., a fiber optic cable) could perhaps be modeled as an approximately one-dimensional system. In this paper we rigorously explore the validity of such intuition from the perspective of a localized probe coupling to a quantum field inside a cav...

[Phys. Rev. A 104, 013723] Published Wed Jul 28, 2021

]]>It is not possible to obtain information about the observable properties of a quantum system without a physical interaction between the system and an external meter. This physical interaction is described by a unitary transformation of the joint quantum state of the system and the meter, which means...

[Phys. Rev. A 104, 012219] Published Tue Jul 27, 2021

]]>The problem of discriminating between many quantum channels with certainty is analyzed under the assumption of prior knowledge of algebraic relations among possible channels. It is shown, by explicit construction of a novel family of quantum algorithms, that when the set of possible channels faithfu...

[Phys. Rev. A 104, 012425] Published Tue Jul 27, 2021

]]>We propose key-sifting algorithms for a continuous-variable quantum key distribution (CV-QKD) protocol using a machine-learning framework based on the isolation forest and a traditional digital signal-processing scheme based on the Wiener filter. In previous works, the key-sifting procedure performs...

[Phys. Rev. A 104, 012616] Published Tue Jul 27, 2021

]]>We simulate the photoemission from an electronically excited system by computing the escape of electron density in real space using time-dependent density functional theory in real time. We show that for a one-electron system, the angular resolved photoemission after an initial excitation can be int...

[Phys. Rev. A 104, 012815] Published Tue Jul 27, 2021

]]>We propose and experimentally demonstrate a noninterferometric method to quantitatively determine the topological charge and complete phase structure of a vortex beam scrambled by a random scattering medium. In the proposed technique, the vortex beam with an arbitrary topological charge coaxially en...

[Phys. Rev. A 104, 013525] Published Tue Jul 27, 2021

]]>The Rabi Hamiltonian, describing the interaction between a two-level atomic system and a single-cavity mode of the electromagnetic field, is one of the fundamental models in quantum optics. The model becomes exactly solvable by considering an atom without permanent dipole moments, whose excitation e...

[Phys. Rev. A 104, 013722] Published Tue Jul 27, 2021

]]>We study energetic exchanges and fluctuations in two-stroke quantum thermodynamic engines where the working fluid is represented by two multilevel quantum systems, i.e., qudits, the heat flow is allowed by relaxation with two thermal reservoirs at different temperatures, and the work exchange is ope...

[Phys. Rev. A 104, 012217] Published Mon Jul 26, 2021

]]>We investigate the properties of two anti-parity-time (anti-$\mathcal{PT}$)-symmetric four-site scattering centers. The anti-$\mathcal{PT}$-symmetric scattering center may have imaginary couplings, real couplings, and real on-site potentials. The only difference between the two scattering centers is the coupling between tw...

[Phys. Rev. A 104, 012218] Published Mon Jul 26, 2021

]]>Strong nonlocality based on local distinguishability is a stronger form of quantum nonlocality recently introduced in multipartite quantum systems: an orthogonal set of multipartite quantum states is said to have the property of strong nonlocality if it is locally irreducible for every bipartition o...

[Phys. Rev. A 104, 012424] Published Mon Jul 26, 2021

]]>The quantum level population behavior of two coupled flux qubits depending on the external driving field characteristics is studied. Explicit expressions for the multiphoton transition probabilities at an arbitrary control field amplitude are obtained for the case of small tunnel splitting energies....

[Phys. Rev. A 104, 012613] Published Mon Jul 26, 2021

]]>Quantum computation has seen rapid progress in the past years. Due to implementation complexity and cost, cloud-based quantum computing is strongly believed to be the most feasible framework for individual users. Universal blind quantum computing (UBQC) provides the protocol for secure delegation of...

[Phys. Rev. A 104, 012614] Published Mon Jul 26, 2021

]]>Neutral atoms are promising for large-scale quantum computing, but accurate neutral-atom entanglement depends on large Rydberg interactions which strongly limit the interatomic distances. Via a phase accumulation in detuned Rabi cycles enabled by a Rydberg interaction of similar magnitude to the Ryd...

[Phys. Rev. A 104, 012615] Published Mon Jul 26, 2021

]]>In a combined experimental and theoretical study we investigate the $7dnl$ and $8pnl$ ($n\ge 11,l=9\u201312$) doubly excited planetary states of Sr. The experimental spectrum was obtained using a five-photon resonant excitation scheme. The method of configuration interaction with exterior complex scaling was use...

[Phys. Rev. A 104, 012812] Published Mon Jul 26, 2021

]]>Measured and calculated positron binding energies are presented for a range of hydrocarbons with up to six carbon atoms (viz., methane, acetylene, ethylene, ethane, propane, butane, and hexane) and their chlorinated counterparts. Both experiment and theory confirm the large effect that the chlorine ...

[Phys. Rev. A 104, 012813] Published Mon Jul 26, 2021

]]>We develop an analytic-gradient-based method for relativistic coupled-cluster calculations of effective electric field ${\mathcal{E}}_{\text{eff}}$ with improved efficiency and robustness over the previous state of the art. The enhanced capability to calculate this time-reversal-symmetry-violation sensitivity parameter ena...

[Phys. Rev. A 104, 012814] Published Mon Jul 26, 2021

]]>We study theoretically x-ray absorption and ionization spectra of an atom or molecule by two coherent x-ray pulses that show a relative phase shift resulting in a time delay of the pulse envelopes. We demonstrate that the phase modulation of the spectra is shifted with respect to the phase oscillati...

[Phys. Rev. A 104, 013114] Published Mon Jul 26, 2021

]]>We study interactions between multiple temporal pairs of slits in coherent control of photoionization of $S$-state atoms using a pulse train of $N+1$ pairs evenly delayed in time by $\tau $, in which the two pulses in a pair with a delay ${\tau}_{0}$ are counter-rotating circularly polarized. For interacting two double...

[Phys. Rev. A 104, 013115] Published Mon Jul 26, 2021

]]>We present a method to estimate the backward rescattering time of a tunnel-ionized electron in an intense laser pulse. The idea of the classical backpropagation method is applied to determine the backward rescattering time and its dependence on various parameters such as the ionization potential of ...

[Phys. Rev. A 104, 013116] Published Mon Jul 26, 2021

]]>Systems consisting of cold atoms trapped near photonic crystal waveguides have recently emerged as an exciting platform for quantum atom-light interfaces. Such a system enables realization of tunable long-range interactions between internal states of atoms (spins), mediated by guided photons. Curren...

[Phys. Rev. A 104, 013523] Published Mon Jul 26, 2021

]]>Optical cavities are an enabling technology of modern quantum science: From their essential role in the operation of lasers to applications as flywheels in atomic clocks and interaction-enhancing components in quantum optics experiments, developing a quantitative understanding of the mode shapes and...

[Phys. Rev. A 104, 013524] Published Mon Jul 26, 2021

]]>[Phys. Rev. A 104, 019902] Published Mon Jul 26, 2021

]]>Highly accurate and robust control of quantum operations is vital for the realization of error-correctible quantum computation. In this paper, we show that the robustness of high-precision controls can be remarkably enhanced through sampling-based stochastic optimization of a risk-sensitive (RS) los...

[Phys. Rev. A 104, 012422] Published Fri Jul 23, 2021

]]>We present a time-dependent quantum algorithm for nuclear inelastic scattering in the time-dependent basis function on qubits approach. This algorithm aims to quantum simulate a subset of the nuclear inelastic scattering problems that are of physical interest in which the internal degrees of freedom...

[Phys. Rev. A 104, 012611] Published Fri Jul 23, 2021

]]>Quantum entanglement is at the heart of quantum information sciences and quantum technologies. In the optical domain, the most common type of quantum entanglement is polarization entanglement, which is usually created in a postselection manner involving destructive photon detection and thus hinderin...

[Phys. Rev. A 104, 012612] Published Fri Jul 23, 2021

]]>We show an implementation of a $\kappa $-deformed Dirac equation in tight-binding arrays of photonic waveguides. This is done with a special configuration of couplings extending to second-nearest neighbors. Geometric manipulations can control these evanescent couplings. A careful study of wave packet propag...

[Phys. Rev. A 104, 013522] Published Fri Jul 23, 2021

]]>We demonstrate the optomechanically induced Faraday and splitting effects caused by optical mode conversion in a double-cavity optomechanical system. In the scheme, the polarization states of propagating light fields can be arbitrarily tailored to achieve optical Faraday rotation successfully via op...

[Phys. Rev. A 104, 013721] Published Fri Jul 23, 2021

]]>We present a method for the direct measurement of the Wigner characteristic function of a thermalizing harmonic oscillator that is completely inaccessible for control or measurement. The strategy employs a recently proposed probe-measurement-based scheme [Phys. Rev. Lett. **122**, 110406 (2019)] which r...

[Phys. Rev. A 104, 012421] Published Thu Jul 22, 2021

]]>The electric-field-dependent $g$ factor and the electron electric dipole moment (eEDM)-induced Stark splittings for the lowest rotational levels of ${}^{207,208}\mathrm{PbF}$ are calculated. Observed and calculated Zeeman shifts for ${}^{207}\mathrm{PbF}$ are found to be in very good agreement. It is shown that the ${}^{207}\mathrm{PbF}$ hyperfine ...

[Phys. Rev. A 104, 012811] Published Thu Jul 22, 2021

]]>The interplay between interparticle interactions and topological features may result in unusual phenomena. Interestingly, interactions may induce topological features in an originally trivial system, as we illustrate for the case of a one-dimensional two-component Hubbard model in which one componen...

[Phys. Rev. A 104, 013315] Published Thu Jul 22, 2021

]]>The phase diagram of lowest-energy vortices in the polar phase of spin-1 Bose-Einstein condensates is investigated theoretically. Singly quantized vortices are categorized by the local ordered state in the vortex core and three types of vortices are found as lowest-energy vortices, which are ellipti...

[Phys. Rev. A 104, 013316] Published Thu Jul 22, 2021

]]>The non-Hermitian system has been widely studied recently in various fields from quantum physics to condensed matter, in which the “exceptional point” (EP) as an essential feature of the systems can be used to design sensors, for example, a mass sensor to detect the mass of nano-objects. Inspired by...

[Phys. Rev. A 104, 013521] Published Thu Jul 22, 2021

]]>We present an experimental and theoretical study of the response of a dipolar supersolid to a Bragg excitation at high-energy defined by the impulse approximation regime. We experimentally observe a continuous reduction of the response when tuning the contact interaction from an ordinary Bose-Einste...

[Phys. Rev. A 104, L011302] Published Thu Jul 22, 2021

]]>We consider topological protection mechanisms in dissipative quantum systems in the presence of quenched disorder, with the intent to prolong the coherence time of a fiducial qubit. The qubit is part of a network of other qubits and dissipative cavities whose coupling parameters are tunable, such th...

[Phys. Rev. A 104, 012216] Published Wed Jul 21, 2021

]]>We consider entanglement purification protocols for multiple copies of qubit states. We use high-dimensional auxiliary entangled systems to learn about the number and positions of errors in the noisy ensemble in an explicit and controlled way, thereby reducing the amount of noise in the ensemble and...

[Phys. Rev. A 104, 012419] Published Wed Jul 21, 2021

]]>Quantum resources and protocols are known to outperform their classical counterparts in a variety of communication and information processing tasks. Random access codes (RACs) are one such cryptographically significant family of bipartite communication tasks, wherein the sender encodes a data set (t...

[Phys. Rev. A 104, 012420] Published Wed Jul 21, 2021

]]>Composite pulse sequences, which produce arbitrary predefined rotations of a qubit on the Bloch sphere, are presented. The composite sequences contain up to 17 pulses and can compensate up to 8 orders of experimental errors in the pulse amplitude and the pulse duration. Composite sequences for three...

[Phys. Rev. A 104, 012609] Published Wed Jul 21, 2021

]]>Counterfactual communication protocols are analyzed using three approaches: a classical argument, the weak trace criterion, and the Fisher information criterion. It is argued that the classical analysis leads to contradiction and should therefore be abandoned. The weak trace and Fisher information c...

[Phys. Rev. A 104, 012610] Published Wed Jul 21, 2021

]]>We explore the spatial enantioseparation of gaseous chiral molecules for the cyclic three-level systems coupled with three electromagnetic fields. Due to molecular rotations, the specific requirements of the polarization directions of the three electromagnetic fields lead to the space-dependent part...

[Phys. Rev. A 104, 013113] Published Wed Jul 21, 2021

]]>The Wigner function ${W}_{N}(\mathbf{x},\mathbf{p})$ is a useful quantity to characterize the quantum fluctuations of an $N$-body system in its phase space. Here we study ${W}_{N}(\mathbf{x},\mathbf{p})$ for $N$ noninteracting spinless fermions in a $d$-dimensional spherical hard box of radius $R$ at temperature $T=0$. In the large-$N$ limit, the local-density...

[Phys. Rev. A 104, 013314] Published Wed Jul 21, 2021

]]>Metal nanoparticles (MNPs) possess the intriguing property of enhancing and limiting the energy of light field to subwavelength scale, which have attracted extensive attention in physics, chemistry, and life sciences. Meanwhile, squeezing is a general concept in quantum optics and can be used to eng...

[Phys. Rev. A 104, 013717] Published Wed Jul 21, 2021

]]>We consider the analogy between gravitational fields and optical media within the framework of geometrical optics in curved spacetime in order to describe how light can acquire orbital angular momentum (OAM) when it traverses the gravitational field of a massive rotating compact object; in particula...

[Phys. Rev. A 104, 013718] Published Wed Jul 21, 2021

]]>We investigate the collective scattering of coherent light from a thermal alkali-metal vapor with temperatures ranging from 350 to 450 K, corresponding to average atomic spacings between $0.7\lambda $ and $0.1\lambda $. We develop a theoretical model treating the atomic ensemble as coherent, interacting, radiating di...

[Phys. Rev. A 104, 013719] Published Wed Jul 21, 2021

]]>We investigate the dynamics of a giant atom (or atoms) in a waveguide QED scenario, where the atom couples to the coupled resonator waveguide via two sites. For a single-giant-atom setup, we find that the atomic dissipation rate can be adjusted by tuning its size. For the two-giant-atom system, the ...

[Phys. Rev. A 104, 013720] Published Wed Jul 21, 2021

]]>Manipulation of a quantum system requires the knowledge of how it evolves. To impose that the dynamics of a system becomes a particular target operation (for any preparation of the system), it may be more useful to have an equation of motion for the dynamics itself, rather than the state. Here we de...

[Phys. Rev. A 104, 012215] Published Tue Jul 20, 2021

]]>The past two decades have witnessed a surge of interest in borrowing tools from quantum information theory to investigate quantum phase transitions (QPTs). The best-known examples are entanglement measures whose nonanalyticities at critical points were tied to QPTs in a plethora of physical models. ...

[Phys. Rev. A 104, 012418] Published Tue Jul 20, 2021

]]>Universal quantum gates play a critical role in quantum information processing. Here, based on the scattering property of photons off single emitters in one-dimensional waveguides, we present some heralded protocols for realizing controlled-not, Toffoli, and Fredkin gates on hybrid systems. The cont...

[Phys. Rev. A 104, 012608] Published Tue Jul 20, 2021

]]>The authors use a previously developed free-electron-gas model to calculate cross sections for collisions of positronium with O_2 and CO_2 molecules. The results agree with previous experimental observations showing a similarity between electron and Ps scattering when the cross section is plotted as a function of projective velocity.

[Phys. Rev. A 104, 012810] Published Tue Jul 20, 2021

]]>We present numerical simulations of the time delay in photoemission of asymmetric diatomic molecules using the technique of reconstruction of attosecond beating by interference of two-photon transitions (RABITT) by solving the time-dependent Schrödinger equation. Our results show an obvious time del...

[Phys. Rev. A 104, 013110] Published Tue Jul 20, 2021

]]>In the context of dynamical control, non-Hermitian systems offer unique opportunities and challenges. In the simplest case of two interacting levels with gain and/or loss, the existence of an exceptional point (EP) of degeneracy in the chiral complex eigenvalue landscape fundamentally changes how th...

[Phys. Rev. A 104, 013111] Published Tue Jul 20, 2021

]]>We theoretically investigate the spontaneous quantum emission of phonon pairs by superradiant processes in an atomic Bose-Einstein condensate subject to a synthetic vector potential. Within the analog gravity perspective, this effect corresponds to the spontaneous emission of radiation from the ergo...

[Phys. Rev. A 104, 013313] Published Tue Jul 20, 2021

]]>Coherent perfect absorption (CPA) was introduced as a classical optics phenomenon of a standing-wave absorption by a subwavelength film. In this paper, we develop a theory of CPA of quantized standing waves taking account of a subwavelength thickness of the absorber. This approach allows us to merge...

[Phys. Rev. A 104, 013716] Published Tue Jul 20, 2021

]]>Two important results of quantum physics are the *no-cloning* theorem and the *monogamy of entanglement*. The former forbids the creation of an independent and identical copy of an arbitrary unknown quantum state and the latter restricts the shareability of quantum entanglement among multiple quantum sy...

[Phys. Rev. A 104, L010402] Published Tue Jul 20, 2021

]]>We investigate memory effects in the spin-boson model using a recently proposed measure for non-Markovian behavior based on the information exchange between an open system and its environment. Employing the numerical exact multilayer multiconfiguration time-dependent Hartree approach, we simulate th...

[Phys. Rev. A 104, 012213] Published Mon Jul 19, 2021

]]>The thermodynamic cost of resetting an arbitrary initial state to a particular desired state is lower bounded by Landauer's bound. However, here we demonstrate that this lower bound is necessarily unachievable for every initial state (except possibly the single minimally dissipative input) for any r...

[Phys. Rev. A 104, 012214] Published Mon Jul 19, 2021

]]>We describe a technique for self-consistently characterizing both the quantum state of a single-qubit system, and the positive-operator-valued measure (POVM) that describes measurements on the system. The method works with only 10 measurements. We assume that a series of unitary transformations perf...

[Phys. Rev. A 104, 012416] Published Mon Jul 19, 2021

]]>Quantum states that possess negative conditional von Neumann entropy provide quantum advantage in several information-theoretic protocols including superdense coding, state merging, distributed private randomness distillation, and one-way entanglement distillation. While entanglement is an important...

[Phys. Rev. A 104, 012417] Published Mon Jul 19, 2021

]]>Qubits encoded in hyperfine states of trapped ions are ideal for quantum computation given their long lifetimes and low sensitivity to magnetic fields, yet they suffer from off-resonant scattering during detection, often limiting their measurement fidelity. In ${}^{171}{\text{Yb}}^{+}$ this is exacerbated by a low flu...

[Phys. Rev. A 104, 012606] Published Mon Jul 19, 2021

]]>Nonlinear interactions are recognized as potential resources for quantum metrology, facilitating parameter estimation precisions that scale as the exponential Heisenberg limit of ${2}^{-N}$. We explore such nonlinearity and propose an associated quantum measurement scenario based on the nonlinear interacti...

[Phys. Rev. A 104, 012607] Published Mon Jul 19, 2021

]]>We study the electron-loss-to-continuum (ELC) cusp experimentally and theoretically by comparing the ionization of ${\mathrm{U}}^{89+}$ projectiles in collisions with ${\mathrm{N}}_{2}$ and Xe targets, at a beam energy of 75.91 MeV/u. The coincidence measurement between the singly ionized projectile and the energy of the emitted e...

[Phys. Rev. A 104, 012809] Published Mon Jul 19, 2021

]]>We present a combined analytical and numerical investigation to show how an optimal control field can be designed to generate maximum field-free orientation of molecules for three populated rotational states. Based on a model involving pure rotational ladder-climbing excitation between rotational st...

[Phys. Rev. A 104, 013108] Published Mon Jul 19, 2021

]]>Multipath holographic interference in strong-field quantum tunnel ionization is key to revealing subangstrom attosecond dynamics for molecular movies. This critical subcycle motion is often obscured by longer timescale effects such as ring-shaped patterns that appear in above-threshold ionization (A...

[Phys. Rev. A 104, 013109] Published Mon Jul 19, 2021

]]>The forerunners of the step-modulated sine pulse propagating in Drude dispersive media are calculated in the time domain. Two such problems are solved analytically. In the first problem, the plane source of the electric field is inside the medium. And the second problem considers the normal incidenc...

[Phys. Rev. A 104, 013518] Published Mon Jul 19, 2021

]]>We studied theoretically optical spectra when circularly polarized light obliquely impinges on a slab of a chiral photonic structure with linearly and uniformly spatial varying pitch. The material that we considered locally has a $\overline{4}2m$ point-group symmetry and presents Pockels effect, hence, we contr...

[Phys. Rev. A 104, 013519] Published Mon Jul 19, 2021

]]>We present a theory of frequency comb generation in high-Q ring microresonators with quadratic nonlinearity and normal dispersion and demonstrate that the naturally large difference of the repetition rates at the fundamental and second-harmonic frequencies supports a family of bright soliton frequen...

[Phys. Rev. A 104, 013520] Published Mon Jul 19, 2021

]]>[Phys. Rev. A 104, 019901] Published Mon Jul 19, 2021

]]>Quantum causality violates classical intuitions of cause and effect and is a unique quantum feature different from other quantum phenomena such as entanglement and quantum nonlocality. In order to avoid the detection loophole in quantum causality, we initiate the study of the detection efficiency re...

[Phys. Rev. A 104, L010201] Published Mon Jul 19, 2021

]]>It was recently argued that the pigeonhole principle, which states that if three pigeons are put into two pigeonholes then at least one pigeonhole must contain more than one pigeon, is violated in quantum systems [Proc. Natl. Acad. Sci. USA **113**, 532 (2016)]. An experimental verification of this effe...

[Phys. Rev. A 104, 012212] Published Fri Jul 16, 2021

]]>We present a procedure to construct tensor-network representations of many-body Gaussian states efficiently and with a controllable error. These states include the ground and thermal states of bosonic and fermionic quadratic Hamiltonians, which are essential in the study of quantum many-body systems...

[Phys. Rev. A 104, 012415] Published Fri Jul 16, 2021

]]>As larger, higher-quality quantum devices are built and demonstrated in quantum information applications, such as quantum computation and quantum communication, the need for high-quality quantum memories to store quantum states becomes ever more pressing. Future quantum devices likely will use a var...

[Phys. Rev. A 104, 012605] Published Fri Jul 16, 2021

]]>Calculations of hyperfine splittings in ${\mathrm{H}}_{2}$ are needed for an accurate experimental determination of frequencies of rovibrational transitions and the dissociation energy in ${\mathrm{H}}_{2}$, which are used for experimental tests of quantum electrodynamics for molecules and for searches for new physics beyond the s...

[Phys. Rev. A 104, 012808] Published Fri Jul 16, 2021

]]>An ultrashort laser pulse focused in air creates a plasma that radiates broadband electromagnetic waves. We experimentally compare the generation of microwaves from plasmas produced with two different laser systems that operate in the near- and mid-infrared regimes. Changing the laser wavelength inc...

[Phys. Rev. A 104, 013107] Published Fri Jul 16, 2021

]]>We present a method to enhance the terahertz (THz) wave radiation from a femtosecond laser-induced plasma filament by controlling the local gas density within the filament. We develop a theoretical model for THz generation from a laser-induced air plasma filament and the subsequent propagation proce...

[Phys. Rev. A 104, 013517] Published Fri Jul 16, 2021

]]>Many three-party correlations, including some that are commonly described as genuinely tripartite nonlocal, can be simulated by a network of underlying subsystems that display only bipartite nonsignaling nonlocal behavior. Quantum mechanics predicts three-party correlations that admit no such simula...

[Phys. Rev. A 104, 012210] Published Thu Jul 15, 2021

]]>Small, controllable quantum systems, known as quantum probes, have been proposed to estimate various parameters characterizing complex systems such as the environments of quantum systems. These probes, prepared in some initial state, are allowed to interact with their environment, and subsequent mea...

[Phys. Rev. A 104, 012211] Published Thu Jul 15, 2021

]]>We introduce a method for digital preparation of ground states of simulated Hamiltonians, inspired by cooling in nature and adapted to leverage the capabilities of digital quantum hardware. The cold bath is simulated by a single ancillary qubit, which is reset periodically and coupled to the system ...

[Phys. Rev. A 104, 012414] Published Thu Jul 15, 2021

]]>We construct an Ising Hamiltonian with an engineered energy landscape such that it has a local energy minimum which is near the true global minimum solution and further away from a false minimum. Using a technique established in previous experiments, we design our experiment such that (at least on t...

[Phys. Rev. A 104, 012604] Published Thu Jul 15, 2021

]]>In the present work, the calculations have been performed for dispersion interaction between heavy elements $({\mathrm{Zn}}^{+},$ ${\mathrm{Cd}}^{+},$ ${\mathrm{Hg}}^{+},$ ${\mathrm{Pb}}^{+},\mathrm{Zn},\mathrm{Cd},\mathrm{Hg},\mathrm{and}\mathrm{Pb})$ with graphene and carbon nanotubes by evaluating van der Waals ${C}_{3}$ coefficients using the well-known Lifshitz theory. The dispersion coefficients are ex...

[Phys. Rev. A 104, 012806] Published Thu Jul 15, 2021

]]>Bohr's centenary stopping-power formula is rederived for a free electron gas (FEG) system within the framework of nonrelativistic classical mechanics. A simple and more concise expression for the stopping power of charged particles in FEG is demonstrated on classical grounds. Using semiclassical arg...

[Phys. Rev. A 104, 012807] Published Thu Jul 15, 2021

]]>We study ionization of atoms in strong two-dimensional (2D) laser fields with various forms, numerically and analytically. We focus on the local most-probable tunneling routes (some specific electron trajectories) which correspond to the local maxima of photoelectron momentum distributions (PMDs). B...

[Phys. Rev. A 104, 013106] Published Thu Jul 15, 2021

]]>We study the out-of-equilibrium dynamics of a two-dimensional paraxial fluid of light using a near-resonant laser propagating through a hot atomic vapor. We observe a double shock-collapse instability: a shock (gradient catastrophe) for the velocity as well as an annular (ring-shaped) collapse singu...

[Phys. Rev. A 104, 013515] Published Thu Jul 15, 2021

]]>We analyze the spin structure of weakly and tightly focused random light beams in view of the characteristic decomposition of the $3\times 3$ polarization matrix. We take the incident beam to be a mixture of mutually uncorrelated, orthogonally linearly polarized parts which entails zero spin for the beam bu...

[Phys. Rev. A 104, 013516] Published Thu Jul 15, 2021

]]>Non-Gaussian continuous-variable states play a central role both in the foundations of quantum theory and for emergent quantum technologies. In particular, “cat states,” i.e., two-component macroscopic quantum superpositions, embody quantum coherence in an accessible way and can be harnessed for fun...

[Phys. Rev. A 104, 013715] Published Thu Jul 15, 2021

]]>The nonrelativistic “Ramsey-Flygare relationship” is the most used procedure to obtain semiexperimental nuclear magnetic resonance (NMR) absolute shieldings by a correspondence between NMR shieldings ($\mathit{\sigma}$) and nuclear spin-rotation constants ($\mathit{M}$). One of its generalizations to the relativistic framewor...

[Phys. Rev. A 104, 012805] Published Wed Jul 14, 2021

]]>Technological advances in femtosecond laser sources call for the development of increasingly refined characterization tools implying to enrich the existing panel of operable nonlinear interactions. Toward that end, we have recently proposed a variant of SPIDER (spectral phase interferometry for dire...

[Phys. Rev. A 104, 013514] Published Wed Jul 14, 2021

]]>The authors explore the information leakage in a continuous-variable communication protocol in quantum key distribution due to the asymmetry of the protocol. The proposed symmetric minimum-leakage heralding protocol asymptotically eliminates information leakage in a pure-loss channel and minimizes leakage in a noisy channel.

[Phys. Rev. A 104, 012411] Published Tue Jul 13, 2021

]]>