We investigate vortex states in Bose-Einstein condensates under the combined action of the spin-orbit coupling (SOC), gradient magnetic field, and harmonic-oscillator trapping potential. The linear version of the system is solved exactly. Through the linear-spectrum analysis, we find that by varying the SOC strength and magnetic-field gradient one can perform energy-level inversion. With suitable parameters, initial higher-order vortex states can be made the ground state (GS). The nonlinear system is solved numerically, revealing that the results are consistent with the linear predictions in the case of repulsive intercomponent interactions. On the other hand, intercomponent attraction creates the GS in the form of mixed-mode states in a vicinity of the GS phase-transition points. The spin texture of both vortex- and mixed-mode GSs reveals that they feature the structure of 2D (baby) skyrmions.

A theory is described for a Bloch electron accelerating in a homogeneous external electric field of arbitrary time dependence while interacting with a quantized radiation field. The external electric field is described in the vector potential gauge. The quantum radiation field is described by the free space quantized electromagnetic field in the Coulomb gauge. The instantaneous eigenstates for the Bloch Hamiltonian are introduced as basis states to analyze the Bloch dynamics to all orders in the external electric field; as well, the eigenstates of the free quantum electromagnetic field are utilized as a component of the full basis set to develop a direct time-dependent solution of the Schrödinger equation. As an alternative consideration, the Glauber displacement operator is utilized to transform the original problem to a canonical form. For both the initial and transformed scenarios considered, the first-order solution to the Schrödinger equation is obtained and used to calculate the Bloch electric current in a form useful for studying the spectral content of solids. It is found that the Glauber transformed Hamiltonian and subsequent quantum dynamics is quite effective in providing solid-state band information in general and as noted in the first-order calculated Bloch-electron current.

Recently, there has been an upsurge of interest in quantum thermodynamic devices, notably quantum batteries. Quantum batteries serve as energy storage devices governed by the rules of quantum thermodynamics. Here, we propose a model of a quantum battery wherein the system of interest can be envisaged as a battery, and the ambient environment acts as a charger (dissipation) mechanism, modeled along the ubiquitous quantum Brownian motion. We employ quantifiers such as ergotropy and its (in)coherent manifestations, as well as instantaneous and average powers, to characterize the performance of the quantum battery. We investigate the influence of the bath's temperature and the system's coupling with the environment via momentum and position coordinates on the discharging and recharging dynamics. Moreover, we probe the memory effects of the system's dynamics and obtain a relationship between the system's non-Markovian evolution and the battery's recharging process.

We introduce a characterization scheme for a universal qutrit gate set. Motivated by the rising interest in qutrit systems, we apply our criteria to establish that our hyperdihedral group underpins a scheme to characterize the performance of a qutrit T gate. Our resulting qutrit scheme is feasible, as it requires resources and data analysis techniques similar to resources employed for qutrit Clifford randomized benchmarking. Combining our T gate benchmarking procedure for qutrits with known qutrit Clifford-gate benchmarking enables complete characterization of a universal qutrit gate set.

We report theoretical calculations of the static diamagnetic susceptibility, ${\chi }_0$ of neon and argon atoms. The calculations were performed using a hierarchy coupled-cluster methods combined with application of both the Gaussian and Slater orbital basis sets. We included the complete relativistic correction of order of ${\alpha }^4$, where $\alpha$ is the fine-structure constant, and obtained an estimate of the quantum electrodynamics contributions. The finite nuclear mass and size corrections were also considered but were found to be small. The final results are ${\chi }_0=-8.4786\left(7\right)\times {10}^{-5}{a}_0^3$ for the neon atom and ${\chi }_0=-22.9545\left(32\right)\times {10}^{-5}{a}_0^3$ for the argon atom, where $a_0$ is the Bohr radius. The uncertainties in the last digits, shown in the parentheses, are primarily due to the errors in the nonrelativistic electronic wave function, as well as to the neglected quantum electrodynamics corrections.

We have measured and calculated fully differential cross sections (FDCS) for dissociative capture in 75-keV $p+{\mathrm{H}}_2$ collisions. FDCS were analyzed in the kinetic energy release (KER) ranges 0 to 2.1 eV and 4 to 7 eV for two different molecular orientations. In the latter range, dissociation is dominated by electronic excitation to the $2p{\pi }_{\mathrm{u}}$ state. Here, we observed two-center interference for an orientation in the plane perpendicular to the initial beam axis and parallel to the transverse momentum transfer. The interference pattern is afflicted with a constant phase shift of $\pi$. In the range $\mathrm{KER}=0$ to 2.1 eV, dissociation is dominated by vibrational excitation. Here, we observed structures in the KER dependence, which we interpret as interference between two different paths of the molecular fragments during the dissociation.

Recently, anomalous Floquet topological phases without static counterparts have been observed in different systems, where periodically driven models are realized to support a winding number of 1 and a pair of edge modes in each quasienergy gap. Here, we focus on cold atomic gases in optical lattices and propose a driving scheme that breaks rotation symmetry but maintains inversion symmetry of the instantaneous Hamiltonian, and discover a type of anomalous Floquet topological phase with a winding number larger than 1. By analyzing the condition of band touching under the constraint of symmetries, we map out the phase diagram exactly by varying the driving parameters and discuss the quasienergy spectra of typical topological phases, which can present multiple pairs of edge modes within a single gap. Finally, we suggest to characterize the topology of such phases by detecting the band inversion surfaces via quench dynamics.

The orbital angular momentum (OAM) of a vortex beam has already found significant potential applications in both quantum and classical communication systems. In this study, a realization of a double-slit experiment using a Sagnac interferometer is conducted for the detection and discrimination of vortex beams. Based on the advantages of convenient and adjustable double-slit parameters of our device, we detected multiple vortex beams carrying different OAM modes and superpositions of OAM modes under laser and single-photon illumination. We also analyzed the influence of the slit parameters on the interference pattern of the vortex beams. The results show that by comparing the differences in these interference patterns, we can achieve the measurement of topological charge and complete distinction of OAM states carried by the vortex beams. Our study contributes to coding research on laser and quantum communication.

Relativistically intense laser-driven plasma mirrors offer a promising route to produce attosecond pulses with high brightness. One major challenge is to generate an isolated attosecond pulse instead of a train of attosecond pulses when using multicycle driving lasers. Here we numerically demonstrate a scheme to achieve this goal by using Airy laser beams, whose main intensity self-bends transversely during propagation. The generated attosecond pulses are well separated in space and emitted in different directions. This scheme has the advantage of weak dependence on laser duration and thus is better suited for isolated attosecond pulse generation from a large class of conventional multicycle relativistic lasers worldwide.

We present a theoretical investigation of Vavilov-Cherenkov (VC) radiation by a plane wave or twisted electron. Special emphasis is put on the question of whether and at what conditions the emitted VC photons can be twisted. For this aim we obtain a general expression in the coordinate and momentum representations for the quantum state of the final electron-photon system that is a result of the radiation process itself and does not depend on the properties of a detector. It is shown that this evolved state is an entangled state of an electron and a photon, and both particles can be twisted. A direct consequence of this result follows: if one uses a detector sensitive to the twisted electron (photon) with the definite projection of the total angular momentum (TAM), then the final photon (electron) also will be in the twisted state with a definite TAM projection. Further, we investigate the polarization properties of the final twisted photon in more general conditions than have been calculated before. Finally, we exploit a close similarity between the discussed VC radiation and the process of the equivalent photon emission in the Weizsäcker-Williams method and find the corresponding final state.

We show how the localization landscape, originally introduced to bound low-energy eigenstates of disordered wave media and many-body quantum systems, can form the basis for hardware-efficient quantum algorithms for solving binary optimization problems. Many binary optimization problems can be cast as finding low-energy eigenstates of Ising Hamiltonians. First, we apply specific perturbations to the Ising Hamiltonian such that the low-energy modes are bounded by the localization landscape. Next, we demonstrate how a variational method can be used to prepare and sample from the peaks of the localization landscape. Numerical simulations of problems of up to ten binary variables show that the localization landscape-based sampling can outperform quantum approximate optimization algorithm (QAOA) circuits of similar depth, as measured in terms of the probability of sampling the exact ground state.

Nonadiabatic holonomic quantum gates are high-speed and robust. Nevertheless, they were found to be more fragile than the adiabatic gates when systematic errors become dominant. Inspired by the dark-path scheme that was used to partially relieve the systematic error in the absence of external noise, we construct a universal set of nonadiabatic holonomic $N$-qubit gates using the Rydberg-Rydberg interaction between atoms under off-resonant driving. Based on an effective four-level configuration in the Rydberg-atom system, the modified nonadiabatic holonomic geometric gates present a clear resilience to both systematic error in the whole parametric range and external noise. In our scheme, the conventional ultrastrong interaction between control atoms and the target atom for the nonadiabatic holonomic quantum computation is compensated by the detuning of the driving fields on the target atom. That idea yields a deeper understanding about the holonomic transformation. Moreover, our scheme is compact and scale-free with respect to $N$. It is interesting to find that the three-qubit gate is less susceptible to errors than the double-qubit one.

With a finite amount of measurement data acquired in variational quantum algorithms, the statistical benefits of several optimized numerical estimation schemes, including the scaled parameter-shift (SPS) rule and finite-difference (FD) method, for estimating gradient and Hessian functions over analytical schemes [unscaled parameter-shift (PS) rule] were reported by the present author [Phys. Rev. A 107, 042421 (2023)]. We continue the saga by exploring the extent to which these numerical schemes remain statistically more accurate for a given number of sampling copies in the presence of noise. For noise-channel error terms that are independent of the circuit parameters, we demonstrate that without any knowledge about the noise channel, using the SPS and FD estimators optimized specifically for noiseless circuits can still give lower mean-squared errors than PS estimators for substantially wide sampling-copy number ranges—specifically for SPS, closed-form mean-squared error expressions reveal that these ranges grow exponentially in the qubit number and reciprocally with a decreasing error rate. Simulations also demonstrate similar characteristics for the FD scheme. Lastly, if the error rate is known, we propose a noise-model-agnostic error-mitigation procedure to optimize the SPS estimators under the assumptions of two-design circuits and circuit-parameter-independent noise-channel error terms. We show that these heuristically optimized SPS estimators can significantly reduce mean-squared-error biases that naive SPS estimators possess even with realistic circuits and noise channels, thereby improving their estimation qualities even further. The heuristically optimized FD estimators possess as much mean-squared-error biases as the naively optimized counterparts and are thus not beneficial with noisy circuits.

The two-center wave-packet convergent close-coupling approach is extended to model dressed ion collisions with atomic hydrogen. This is done by reducing the problem to an effective three-body one and using a model potential to approximate the interactions between the projectile ion with the target electron and target nucleus. The method is applied to calculate the total ionization cross section along with the total and $n$-resolved electron-capture and target-excitation cross sections in partially stripped ${\mathrm{C}}^{2+}$ and ${\mathrm{C}}^{3+}$ ion collisions with ground-state atomic hydrogen. Calculations are performed across a broad projectile energy range from 1 keV/u to 1 MeV/u, where one-electron collision processes are dominant. The calculated total electron-capture cross sections for both systems generally agree very well with available experimental and previous theoretical data. We find that at incident energies above 100 keV/u the total electron-capture cross sections in dressed carbon-ion collisions are larger than the ones corresponding to collisions of bare projectile ions of the same charge. A possible reason for this could be associated with the target-electron radial density and the behavior of the potential of interaction between the target electron and the carbon ion. Our results for ionization in ${\mathrm{C}}^{3+}+\mathrm{H}\left(1s\right)$ collisions overestimate the experimental data. We also report a set of calculations for ionization in ${\mathrm{C}}^{2+}+\mathrm{H}\left(1s\right)$ collisions.

The electronic energy loss rate from an energetic proton to electrons of an alkali metal magnesium (Mg) is investigated using real-time time-dependent density functional theory. Nonequilibrium simulations under various impact geometries are conducted to elucidate the role of the impact parameter in the dissipation mechanism. Unlike electronic stopping, which is significantly underestimated under channeling trajectories in the velocity regime around and above the stopping maximum, the predicted electronic stopping along the off-channeling trajectory, which explicitly accounts for the occasionally strong interaction with tightly bound inner-shell electrons, demonstrates quite satisfactory agreement with the experimental data throughout the velocity regime considered. This suggests that the impact parameter plays a crucial role when inner-shell excitation is concerned. Moreover, we conduct a quantitative analysis of the effect of the impact parameter on the electronic excitation in specific bands. An important conclusion drawn is that reducing the impact parameter significantly increases the intensity of the inner-shell excitation, especially for regimes around and above the stopping maximum, and it would also shift the excitation threshold to a lower velocity.

The YbOH molecule is one of the most sensitive systems for electron electric dipole moment (eEDM) searches. The eEDM-induced energy shift is proportional to the polarization $P$ of the molecule. Petrov and Zakharova [A. Petrov and A. Zakharov, Phys. Rev. A 105, L050801 (2022)] showed that the value of $l$ doubling and spin-rotation splitting directly influence the maximum value of $P$. Recently, Jadbabaie et al. [A. Jadbabaie, Y. Takahashi, N. H. Pilgram, C. J. Conn, Y. Zeng, C. Zhang, and N. R. Hutzler, New J. Phys. 25, 073014 (2023)] determined the corresponding energy levels experimentally. We introduce electronic matrix elements in the Hund's case $c$ coupling scheme to reproduce experimental energy levels and calculate $P$ as a function of external electric field.

We establish an energy conservation law for tunneling electrons driven by a circularly polarized light in a rotationally invariant potential. This conservation law emerges from the adiabaticity of the ionization process when described in the frame rotating with the laser field. It offers a clear picture of nonlinear phenomena observed in strong fields for initial states carrying a magnetic quantum number. It provides unambiguous sets of trajectories to model and interpret cutting-edge experiments using semiclassical approaches.

Canonical nonlinear optics treats self-focusing as a deterministic beam evolution scenario, unfolding above the self-focusing threshold due to the intensity-dependent change in the refractive index. While this deterministic view is adequate for a vast class of nonlinear processes, its insight into stochastic nonlinear phenomena, including laser-induced damage and self-focusing-enhanced spectral transformations, is limited. Here, we present a stochastic treatment of self-focusing. We derive a closed-form analytical solution for the count rate of extreme self-focusing events in nonlinear beam dynamics below the self-focusing threshold. We show that the rare-event statistics of subthreshold self-focusing is highly sensitive to the signal-to-noise ratio and the bandwidth of the laser field waveform. For low-signal-to-noise beams, the rare-event distribution of deeply subthreshold self-focusing is shown to exhibit a manifestly nonexponential tail, thus indicating the enhancement of extreme self-focusing events. We show that subthreshold self-focusing is further enhanced by a broader bandwidth of the noise component of the laser field. It is such broadband, low-signal-to-noise laser fields that are especially prone to deeply subthreshold, rogue-wave self-focusing, lowering, via a laser-induced breakdown, the lifetime of downstream optics.