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From the perspective of resource theory, it is interesting to achieve the same quantum task using as few quantum resources as possible. Semiquantum key distribution (SQKD), which allows a quantum user to share a confidential key with a classical user who prepares and operates qubits on only one basis, is an important example for studying this issue. To further limit the quantum resources used by users, in this paper, the first SQKD protocol is constructed, which restricts the quantum user to prepare quantum states on only one basis and removes the classical user's measurement capability. Furthermore, it is proven that the constructed protocol is secure against the restricted attack by deriving a key rate expression of the error rate in the asymptotic scenario. The work in this paper provides inspiration for achieving quantum superiority with minimal quantum resources. [ABSTRACT FROM AUTHOR]

This paper explores the groundbreaking contributions of Hermann von Helmholtz and Erwin Schrödinger to the geometry of color space ‐a 3D space that correlates color distances with perceptual differences. Drawing upon his expertise in non‐Euclidean geometry, physics, and psychophysics, Helmholtz introduced the first Riemannian line element in color space between 1891 and 1892, inaugurating a new line of research known as higher color metric, a term coined by Schrödinger in 1920. During his tenure at the University of Vienna, Schrödinger extensively worked on color theory and rediscovered Helmholtz's forgotten line element. In his 1920 papers titled "Grundlinien einer Theorie der Farbmetrik im Tagessehen," published in the Annalen der Physik, Schrödinger elucidated certain shortcomings in Helmholtz's model and proposed his refined version of the Riemannian line element. This study delves into this captivating chapter in the history of color science, emphasizing the profound impact of Helmholtz's and Schrödinger's work on subsequent research in color metrics up to the present day. [ABSTRACT FROM AUTHOR]

In this paper, the higher energy levels of the transmon qubit are taken into consideration to investigate the continuous variable entanglement generation between the transmon qubit and the single‐mode cavity. Based on the framework of cavity Quantum Electrodynamics (QED), the authors show the entanglement generation depends on the driving field intensity, coupling strength, cavity field frequency, and qubit frequency. The numerical results show that strong entanglement can be generated by properly tuning these parameters. It is hoped that the results presented in this paper may lead to a better understanding of quantum entanglement generation in cavity QED systems and provide new perspectives for further research in quantum information processing. [ABSTRACT FROM AUTHOR]

This paper proposes a 32‐tupling frequency millimeter‐wave (MMW) filter‐free system based on four Mach‐Zehnder Modulators (MZM) connected in parallel and cascaded with a simple radio‐fiber (RoF) link structure. The four MZMs are all at the maximum transmission point (MATP), and the radio frequency (RF) driving voltage phase difference between MZMs is π /2. The center carrier is suppressed by using an optical attenuator (OATT) and an optical phase shifter (OPS). Two parallel MZMs can generate ±8th order and ±12th order optical sidebands, and the ±4th order optical sidebands can be suppressed by adjusting the modulation index m of the MZM, using cascaded two dual‐parallel MZMS(DPMZM) and the phase difference of the RF signal source is π/4 to generate ±16th order optical sidebands. The theoretical analysis and simulation experiments are performed for the scheme proposed in this paper. The results show that the simulated and theoretical values of the optical sideband suppression ratio (OSSR) for ±16th order optical sideband signals are 60.02 and 59.96 dB, respectively, and the simulated and theoretical values of the RF sideband suppression ratio (RFSSR) for the 32‐tupling MMW signal are 56.34 and 53.94 dB, respectively. [ABSTRACT FROM AUTHOR]

The third observing run (O3) of Advanced LIGO and Advanced Virgo started in April 2019 and ended in March 2020 due to the pandemic. From the O3 run three catalogs of compact binary mergers, GWTC‐2, GWTC‐2.1, and GWTC‐3, that include also some exceptional events, are produced by the LIGO/Virgo Collaboration. The paper will review the science results about compact binary mergers during the O3 run and the follow‐up of gravitational wave candidate events involving the whole electromagnetic spectrum and neutrinos. No confirmed counterpart is found during the O3 run for any candidate. The impact of detected events on astrophysics and cosmology will also be discussed. The paper will also briefly summarize additional multi‐messenger investigations involving candidates not initially associated to gravitational events. [ABSTRACT FROM AUTHOR]

Quantitative climate mobility research has, so far, focused primarily on climate change impacts on migration outcomes. This focus has led to a separation between quantitative climate migration research and the broader field of migration studies. In this paper ways are proposed for quantitative research to better address the complexity in the relationship between climate change and mobility. First technical suggestions are presented to improve upon migration model setups and designs and highlight promising developments. Then it is argued that quantitative methodologies can broaden the scope of research inquiries by examining how climate mitigation and adaptation efforts influence mobility, as well as assessing how mobility itself impacts vulnerability. [ABSTRACT FROM AUTHOR]

In this paper, the introduction of a novel type of electron beams known as electron odd‐Pearcey Gaussian beams (EOPGBs) is presented. For the first time, the dynamics of EOPGBs are explored propagating in both free space and a constant magnetic field by employing the Schrödinger equation. The investigation reveals that the electron beams exhibit remarkable auto‐focusing characteristics in these two media, and the focal length can be controlled by adjusting certain parameters. Additionally, in a constant magnetic field, EOPGBs exhibit intriguing properties, notably the dual auto‐focusing property, which sets them apart from other known electron beams. The probability currents and distribution factors are used to provide a theoretical explanation for the aforementioned features of EOPGBs. Furthermore, the conclusions are consistent with the results obtained from numerical simulations. [ABSTRACT FROM AUTHOR]

In this paper, symmetric Pearcey Gaussian beams (SPGBs) are studied in a Kerr medium. By varying the initial input power, the autofocusing ability of the beams is investigated, to find a clear restrictive relationship between the breath‐like structure and the initial input power. The critical collapse power is investigated when SPGBs change from discrete beams to regular breath‐like structure. Finally, the transmission of SPGBs is discussed under different phase modulation when SPGBs are affected by astigmatic, the whole beam is rotated and the angle of rotation can be controlled. [ABSTRACT FROM AUTHOR]

The adaptive voter model is widely used to model opinion dynamics in social complex networks. However, existing adaptive voter models are limited to only pairwise interactions and fail to capture the intricate social dynamics that arises in groups. This paper extends the adaptive voter model to hypergraphs to explore how forces of peer pressure influence collective decision‐making. The model consists of two processes: individuals can either consult the group and change their opinion or leave the group and join a different one. The interplay between those two processes gives rise to a two‐phase dynamics. In the initial phase, the topology of the hypergraph quickly reaches a new stable state. In the subsequent phase, opinion dynamics plays out on the new topology depending on the mechanism by which opinions spread. If the group always follows the majority, the network rapidly converges to fragmented communities. In contrast, if individuals choose an opinion proportionally to its representation in the group, the system remains in a metastable state for an extended period of time. The results are supported both by stochastic simulations and an analytical mean‐field description in terms of hypergraph moments with a moment closure at the pair level. [ABSTRACT FROM AUTHOR]

Dielectric mirrors comprising thin‐film multilayers are widely used in optical experiments because they can achieve substantially higher reflectance compared to metal mirrors. Here, potential problems are investigated that can arise when dielectric mirrors are used at oblique incidence, in particular for focused beams. It is found that light beams reflected from dielectric mirrors can experience lateral beam shifts, beam‐shape distortion, and depolarization, and these effects have a strong dependence on wavelength, incident angle, and incident polarization. Because vendors of dielectric mirrors typically do not share the particular layer structure of their products, several dielectric‐mirror stacks are designed and simulated, and then the lateral beam shift from two commercial dielectric mirrors and one coated metal mirror is also measured. This paper brings awareness of the tradeoffs between dielectric mirrors and front‐surface metal mirrors in certain optics experiments, and it is suggested that vendors of dielectric mirrors provide information about beam shifts, distortion, and depolarization when their products are used at oblique incidence. [ABSTRACT FROM AUTHOR]

The formation and stability of solids and molecules is not possible without chemical bonds, which are divided into covalent, ionic, metallic, and van der Waals bonds. A special type of intermolecular bond is hydrogen bonding, which plays a crucial role for chemical, biological, and physical processes. However, hydrogen shows a far more complex behavior when it is present in solids. In this paper, it is shown that the chemical bonding of hydrogen atoms and molecules extends far beyond the simple picture of conventional, ionic, covalent, and multicenter bonds. The interaction of H with its host material is particularly important for hydrogen storage in metallic materials such as Ti3C2${\rm Ti}_{3}{\rm C}_{2}$ MXenes. Hydrogen atoms and H2${\rm H}_2$ molecules form multicenter bonds in Ti3C2${\rm Ti}_{3}{\rm C}_{2}$. On the surface and between two Ti3C2${\rm Ti}_{3}{\rm C}_{2}$ sheets this is limited to the formation of H–Ti bonds. However, H and H2${\rm H}_2$ on interstitial sites form multicenter bonds not only with nearest neighbor Ti atoms but also with carbon atoms. Interestingly, the H–C bonds are characterized by the formation of s–p hybrid orbitals. For H2${\rm H}_2$ molecules, multicenter bond formation is accompanied by an increase of the bond length to 2.07 and 1.85 Å for H2${\rm H}_2$ on the surface and at the interstitial site, respectively. On the other hand, placing H2${\rm H}_2$ between two sheets of Ti3C2${\rm Ti}_{3}{\rm C}_{2}$ leads to dissociation. For all H and H2${\rm H}_2$ complexes the vibrational eigenmodes are calculated. Their frequencies are in the range of 890 to 1610 cm−1${\rm cm}^{-1}$, which indicates that the bonds are remarkably strong. [ABSTRACT FROM AUTHOR]

The conservation of spectral asymmetry is a fundamental feature of the ideal four‐wave mixing process as it exists in a medium combining quadratic chromatic dispersion and third‐order nonlinearity. The robustness of this invariant in an experimental configuration where the excitation conditions of an optical fiber are sequentially updated, mimicking infinite propagation is tested in this paper. This theoretical and experimental study reveals the high sensitivity of the asymmetry to very slight deviations from the ideal case, and the idealized system behaves as an intermediate case between the ideal case of noncascaded four‐wave mixing and propagation in a system governed by the nonlinear Schrödinger equation is shown. [ABSTRACT FROM AUTHOR]

In this paper, the performance of a unidimensional continuous variable quantum key distribution protocol is analyzed using Gaussian modulated coherent state under fast fading channel. In the fast fading channel, both parties are connected in free space, resulting in a harsh propagation environment and pollution caused by atmospheric turbulence. This pollution makes it difficult for the communicators to determine the channel transmittance, which can only be estimated based on a probability distribution. To address this, only one modulator is used to code, which demonstrates performance equivalent to that of the symmetric modulated Gaussian coherent state protocol. The security of the protocol in the face of collective attacks is analyzed and it is proved that it can accept a certain amount of excessive channel noise while simplifying operations. Simultaneously, the impact of finite‐key length effects on the protocol is analyzed. It is also demonstrated that this protocol can reduce costs within an acceptable range of performance losses, making it more practical. [ABSTRACT FROM AUTHOR]

Hybrid entangled states (HES) have attracted significant attention and been utilized in various quantum information processing applications. However, like many other entangled states, maximally entangled HES may degrade to mixed states due to environmental noise and operational imperfections. In this paper, a hybrid entanglement purification protocol (HEPP) for the HES, which consists of photon‐number state and coherent state is proposed. This HEPP is designed to effectively purify a bit‐flip error occurring in any qubit of the HES. Furthermore, HEPP is extended to a general condition, say, the multi‐party scenario, and integrates the generation of HES into the HEPP. Moreover, if different initial mixed states are chosen, then the residual entanglement can be utilized to distill high‐quality entanglement. The HEPP has important applications in the future quantum information processing field. [ABSTRACT FROM AUTHOR]

In the paper, the possibility of two complete conversions is investigated, one is from the two‐photon hyperentangled Knill–Laflamme–Milburn (KLM) state to hyperentangled Bell states, the other is from three‐photon KLM state to the hyperentangled Greenberger–Horne–Zeilinger states, for photonic systems hyper‐encoded in polarization and spatial degrees of freedom assisted by error‐heralded quantum units (EHQUs). The system inhomogeneity and/or the imperfect photon scattering often restrict the performance of effective conversions of two types of hyperentangled states, and result in the reductions of the fidelity and the efficiency in tangible quantum information technologies. The polarization EHQU and spatial EHQU are two critical tools for actualizing two hyperentangled conversions in a heralded way, as the errors stemming from the system inhomogeneity and practically imperfect scattering are converted into efficacious responses of the detectors in our protocols. Thus, the fidelities of these conversion cases keep unchanged and have close to unity fidelities, which deepen the understanding of the properties of hyperentanglement. [ABSTRACT FROM AUTHOR]

In this paper, a new type of structured electron beam is introduced, which is the electron Airy tornado wave (eATW) with the characteristics of abrupt auto‐focusing and rotation property in free space. It is also found that the eATWs propagate periodically in a magnetic field, and their patterns of intensity distributions show the time‐like axial symmetry about a half‐period point in a period of time. Furthermore, the influence of the magnetic field's magnitude and direction on eATWs with different parameters has also been discussed. [ABSTRACT FROM AUTHOR]

Quantum‐information storage and retrieval in an optimized manner are of significance to information processing with composite systems. In this paper, an effective scheme is proposed for performing rapid information storage and retrieval between microwave photons and a nitrogen‐vacancy electron spin via shortcuts to adiabaticity. A qutrit of composite photon‐spin system interacts with two classical drivings. By modifying two original Rabi drivings, instead of directly adding an auxiliary counter‐diabatic interaction, information storage and retrieval can be rapidly performed with the optimized shortcut dynamics. Benefited from the shorter duration time, the shortcut‐based operation is more insensitive to decoherence effects than that of adiabatic counterpart. This strategy provides a promising avenue toward fast and robust information processing with solid‐state hybrid systems. [ABSTRACT FROM AUTHOR]

Today Noether's principal theorem occupies a prominent place in theoretical physics, though for a long time its significance was largely overlooked. Even now, relatively few physicists realize that Emmy Noether's original paper from 1918 contains two fundamental theorems. Moreover, both theorems are essential for understanding her original motivation, namely to distinguish between proper and improper conservation laws in physics. [ABSTRACT FROM AUTHOR]

This paper investigates the entanglement dynamics of a two‐qubit system in the presence of n‐sequential sin2$ \sin ^2$‐pulse shape. The study explores entanglement under two scenarios: when the system is completely isolated from the environment and when it interacts with one of the surrounding environments, namely the thermal environment and the common dephasing environment. The authors quantify entanglement through concurrence while systematically examining the effects of initial state preparation, qubit coupling strength, laser‐qubit interaction intensity, pulse sequences, and decohering environments. The results highlight that the entanglement of the two‐qubit system strongly depends on the initial state. Increasing the coupling strength between the qubits and the n‐sequential pulse enhances the maximum values of entanglement. Conversely, augmenting the laser‐qubits coupling or introducing the influence of the environment diminishes the entanglement. [ABSTRACT FROM AUTHOR]

In standard quantum mechanics, the coupling between quantum systems is described by a potential interaction term in the Hamiltonian. This type of coupling is well‐rooted in nature and shapes the universe around us, from the interactions between single photons to the attractive force between atoms that forms molecules. Quantum mechanics does not forbid other kinds of interactions to take place. In this paper, a non‐standard quantum coupling between quantum systems is proposed, originated from the kinetic energy rather than the potential interaction in the Hamiltonian. Unlike the potential‐based coupling, the proposed coupling changes the fundamental structure of quantum mechanics in the form of modified uncertainty relations that are shaped by the coupling between the particles in the system. Two prototypical examples of non‐standard systems that perform such kinetic‐based coupling are presented. In the first example, it considers a particle confined in a heterostructure, such as a quantum dot, where the coupling is between the particle and dynamic walls that determine the size of the heterostructure. The second example involves a particle in a 3D heterostructure with coupling between its position axes. It then discusses several future implications of the proposed type of non‐standard coupling. [ABSTRACT FROM AUTHOR]

Gravitational waves (GW) emitted by merging black holes (BH) and neutron stars are now routinely detected. Those are the afterlives of massive stars that formed all across the Universe—at different cosmic times and with different metallicities. Birth metallicity plays an important role in the evolution of massive stars. Consequently, the population properties of mergers are sensitive to the metallicity dependent cosmic star formation history (fSFR(Z,z)). In particular, within the isolated formation scenarios (the focus of this paper), a strong low metallicity preference of the formation of BH mergers is found. The origin of this dependence and its consequences are discussed. Most importantly, uncertainty in the fSFR(Z,z) (substantial even at low redshifts) cannot be ignored in the models. This poses a challenge for the interpretation of the observed GW source population properties. Possible improvements and the role of future GW detectors are considered. Recent efforts to determine fSFR(Z,z) and the factors that dominate its uncertainty are summarized. Many of those factors stem from the uncertain properties of faint and distant galaxies. The fact that they leave imprint on the redshift‐dependent properties of mergers makes GW a promising (and complementary to electromagnetic observations) tool to study galaxy chemical evolution. [ABSTRACT FROM AUTHOR]

In this paper, the time evolution of signals in axion dark matter experiments is considered from a quantum perspective. The aim is to illuminate the specific case of axion experiments and not to contribute new results to the general discussion of the quantum/classical connection. Classically, one expects a signal oscillating with a frequency equal to the axion mass whose amplitude is slowly rising due to the tiny interaction of the axions with ordinary matter. Quantum mechanically the latter time‐scale arises from the small splitting in the energy levels induced by the interaction between the axions and the experiment. It is always present in suitable, sensitive experiments. Signals that oscillate with the axion mass arise from processes changing the axion number. For certain observables such oscillations are absent for special initial quantum states of the axions. Examples are shown where these special states can be affected by the experiment such that a signal oscillating with the axion mass re‐appears. Suitable correlators that feature an oscillation with the axion mass are discussed, and comments on the connection to the classical treatment are provided. Explicitly, the Cosmic Axion Spin Precession Experiment (CASPEr) is studied, but these findings are expected to be adaptable to other axion dark matter searches. [ABSTRACT FROM AUTHOR]

Axions are hypothetical particles that could explain the observed dark matter density and, simultaneously, could naturally resolve the strong charge parity (CP) problem in quantum chromodynamics (QCD). Recent theoretical works indicate that axions are expected to have masses in the range of 40−400μeV$40 - 400\;{\rm{\mu eV}}$, a range that presently still evades experimental detection. An experimental design is presented to search for QCD axions in this mass range via the magnetized disk and mirror axion experiment (MADMAX). MADMAX will be composed of multiple movable dielectric disks and a stable mirror that are placed inside a strong magnetic field to utilize the axion‐induced coherent electromagnetic wave emissions from each disk surface. In this paper, new R&D milestones achieved will be reported, that is, the updated magnet quench protection system, a closed booster dielectric haloscope system tested in the MORPURGO magnet at (European Organization for Nuclear Research) CERN using a full experimental data acquisition chain. These new main novel accomplishments investigate the feasibility of the experiment. [ABSTRACT FROM AUTHOR]

A dark photon is one of the simplest extensions of the Standard Model of particle physics and can be a dark matter candidate. Dark photons kinetically mix with ordinary photons. The mass range from 10−4 to 10−3 eV of such dark photons is underconstrained by laboratory‐based experiments and a new search is therefore motivated. In this mass range, dark photons behave like waves rather than particles and the corresponding electromagnetic waves are in the millimeter‐wave range. The technical difficulties of the millimeter waves have prevented so far dark photon experiments in this mass range. The use of coherent millimeter waves to search for dark photons in a Light‐Shining‐through‐a‐Wall (LSW) experiment is proposed. The merits and limitations of coherent wave detection are clarified and the potential of single photon sensors at microwaves is investigated. Development of millimeter‐wave technology is not only limited to dark photons. Technically, an experiment for dark photons by using electromagnetic waves resembles that for axions, another light dark matter candidate, with static magnetic fields. This paper represents an essential step toward axion LSW in the millimeter‐wave range (Sub‐THz‐AXion experiment; STAX) as a potential successor of an on‐going experiment in infrared. [ABSTRACT FROM AUTHOR]

Contrary to the statement made in Section 2.2. and a paper by Ng et al., the Hamiltonian of the two‐photon quantum Rabi model is self‐adjoint for all ω≥0$\omega \ge 0$. Other results of the article are not affected. [ABSTRACT FROM AUTHOR]