Rovibronic resonances of ozone in the excited electronic state ${}^3{A}_2(0,1,0)$ were observed in the high-sensitivity laser cavity ring-down experiment. Accurate measurements of line broadening for several series of transitions permitted to derive predissociation widths and lifetimes of ${}^3{A}_2$ levels. The rovibrational levels have short lifetimes in the interval 6 to 80 ps due to dissociation towards the quasicontinuum of the ground electronic state $X^1{A}_1$ by the spin-orbit coupling. Analysis of predissociation line broadening in experimental spectra, combined with ab initio calculations of vibrational scattering states, allowed us to assign the resonances as Feshbach-type in the excited ozone. The predissociation is resonantly enhanced by quasibound rovibrational levels of the ${\left\{{\mathrm{O}}_2(v=1)\text{−}\mathrm{O}\right\}}^{*}$ complex in the $X^1{A}_1\mathrm{state}$, which decay to the ${\mathrm{O}}_2(v=0)$-O channel, open at the energy of the resonances.

Floquet engineering in quantum simulation employs externally applied high-frequency pulses to dynamically design steady-state effective Hamiltonians. Such protocols can be used to enlarge the space of Hamiltonians but approximations often limit pulse profile shapes and therefore the space of available effective Hamiltonians. We consider a nonstroboscopic high-frequency expansion formalism for Floquet engineering. We generalize the pulse profiles available by rigorously keeping all necessary terms to lowest order in inverse frequency expansions used to derive the effective Hamiltonians. Our approach allows wide tunability in application of external driving fields. We apply our method to long-range interacting XXZ spin Hamiltonians. We model an example application where we derive conditions on specific pulse shapes to engineer effective Ising models from XXZ models. Our method allows the space of continuous pulse profiles, relevant to experimental control fields, to better and more accurately explore possible effective Hamiltonians available for Floquet engineering.

We report the observation of two distinct types of vector solitons, characterized by asynchronous periodic oscillation behavior in a mode-locked fiber laser. This phenomenon is prevalent in mode-locked fiber lasers but has remained insufficiently investigated. Our observations reveal that the nonsynchronized dynamics manifest as a periodic evolution of the polarization state for vector solitons. The evolution of the polarization state is retrieved through both experimental measurement and numerical simulation. Furthermore, we propose a universal approach for quantitatively tailoring the oscillation periods of asynchronous vector solitons. The experimental observations are in close agreement with both theoretical and numerical results. This work advances the understanding of complex soliton dynamics in nonlinear dissipative systems.

We present a semi-device-independent (SDI) self-testing protocol designed to certify unitary operations within a variant of prepare-measure framework. We consider a communication game which we refer to as a variant of 3-bit prepare-measure random access code (PMRAC) involving two parties, Alice and Bob, who share a prior two-qubit quantum state. Alice encodes her message by applying unitary operations on her subsystem and sends it to Bob. To decode the message, Bob performs a measurement on the whole system. We demonstrate that the optimal quantum advantage of the variant of 3-bit PMRAC over the classical bound enables the self-testing of Alice's unitary operations and Bob's measurements. The derivation of the optimal quantum success probability is fully analytical. The approach is so elegant that it can be generalized for any arbitrary $n$-bit PMRAC and may also be extended to other prepare-measure communication games.

Any proposed solution to the screen problem in quantum mechanics—the challenge of predicting the joint distribution of particle arrival times and impact positions—must align with the extensive data obtained from scattering experiments. In this paper, we conduct a direct consistency check of the absorbing boundary condition (ABC) proposal, a prominent approach to address the screen problem, against the predictions derived from scattering theory (ST). Through a series of exactly solvable one- and two-dimensional examples, we demonstrate that the ABC proposal's predictions are in tension with the well-established results of ST. Specifically, it predicts sharp momentum- and screen-orientation-dependent detection probabilities, along with secondary reflections that contradict existing experimental data. We conclude that while it remains possible that physical detectors described by the ABC proposal could be found in the future, the proposal is empirically inadequate as a general solution to the screen problem, as it is inconsistent with the behavior of detectors in standard experimental settings.

Resonant-exchange scattering plays a key role in many-body dynamics and transport phenomena (such as spin, charge, or excitation diffusion) at low and moderate temperatures. Recent investigations have shown that the locking of phase shifts is central to resonant-exchange scattering at low energies. Moreover, phase-shift locking causes an unexpected behavior, namely the resonant-exchange cross section over a broad range of energies is largely dictated by $s$-wave scattering, the influence of which extends high above the $s$-wave Wigner regime. Here, we generalize our previous treatment to higher energies and derive an analytical expression for the resonant-exchange cross section which depends on a few parameters and accounts not only for the locking of phase shifts, but also for their gradual unlocking with increased energy. We find good agreement between the computed (fully quantal) cross sections and those obtained with our expression, which we illustrate in great detail for the case of resonant charge transfer in ion-atom collisions.

Recent works showed that the Aharonov-Bohm (AB) phase difference for a quantum charged particle can be written in terms of electric and magnetic fluxes in a space-time surface whose boundaries are the possible particle worldlines in the interferometer, relative to the possible paths. After presenting this result in a more detailed way, reinforcing its topological nature, we study the magnetic and electric versions of the AB effect in different inertial reference frames. We find a particular reference frame for a magnetic AB effect where the magnetic flux has a null contribution for the AB phase difference, which is entirely due to an electric flux. Also, we find a particular reference frame for an electric AB effect where the electric flux has a null contribution for the AB phase difference, which is entirely due to a magnetic flux. In this sense, the nomenclatures magnetic AB effect and electric AB effect lose their meaning. We have electromagnetic AB effects.

Quantum error-correcting codes aim to protect information in quantum systems to enable fault-tolerant quantum computations. The most prevalent method, stabilizer codes, has been well developed for many varieties of systems; however, largely the case of a composite number of levels in the system has been avoided. This relative absence is due to the underlying ring theoretic tools required for analyzing such systems. Here we explore composite local-dimension quantum stabilizer codes, providing a pair of constructions for transforming known stabilizer codes into valid ones for composite local dimensions. In addition, remarks on logical encodings and the counts possible are discussed. This work lays out central methods for working with composite dimensional systems, enabling full use of the computational space of some systems and expanding the understanding of the symplectic spaces involved.

Randomized compilation protocols have recently attracted attention as alternatives to traditional deterministic Trotter-Suzuki methods, potentially reducing circuit depth and resource overhead. These protocols determine gate-application probabilities based on the strengths of Hamiltonian terms, as measured by the Schatten-$\infty$ norm. However, relying solely on the Schatten-$\infty$ norm to define sampling distributions may not be optimal, especially for continuous-variable and hybrid-variable systems involving unbounded operators, where quantifying Hamiltonian strengths is challenging. In this work, we propose an adaptive randomized compilation algorithm that dynamically updates sampling weights via low-order moment measurements of Hamiltonian terms, assigning higher probabilities to terms with greater uncertainty. This approach improves accuracy without significantly increasing gate counts and extends randomized compilation to continuous-variable and hybrid-variable systems by addressing the difficulties in characterizing the strengths of unbounded Hamiltonian terms. Numerical simulations demonstrate the effectiveness of our method.

We theoretically investigate the dynamics of quantum information and entanglement of two distant qubits embedded in a thermal dephasing reservoir consisting of three-dimensional Bose-Einstein condensates of microwave-shielded polar molecules. We calculate the decoherence factors, the quantum Fisher information, and the decay rates in terms of the spatial separation between qubits, temperature, and Rabi frequency that tunes the shielding potential. The results show that the dynamics of decoherence factors and the quantum Fisher information are nonmonotonic with revival oscillations at larger separations due to interqubit and qubit-environment correlations. Within our proposed model we can significantly improve the estimation of the environment parameters such as the spectral density, which exhibits a super-Ohmic behavior, and temperature. We demonstrate that the shielding interaction may drive the system from the Markovian to the non-Markovian regime enabling us to well control the information flow dynamics and to reach higher values of entanglement.

Metasurfaces consisting of subwavelength dielectric particles can change the propagation direction of incident light due to the excitation of Mie resonances. Here we investigate the interaction of light with square lattices of subwavelength and wavelength-sized Ge disks formed on a Si substrate. The optical response is strongly dependent on the disk diameter. For lattices with disk diameters of 370–580 nm, pronounced minima are observed in the transmittance and reflectance spectra within the 1000–2000 nm range. In contrast, lattices with larger disk diameters (1160–1490 nm) exhibit spectral modulation across the same wavelength region. The calculations carried out show that for small disks, the effect is associated with Mie resonances, while for large disks, the effect is provided by the excitation of circular Fabry-Perot resonances. The excitation of collective Fabry-Perot modes occurs in the directions along the rows and diagonals of the disk lattice. The simulations of far-field scattering patterns and radiation patterns for a single large Ge disk reveal that circular Fabry-Perot modes promote the redirection of incident light along the substrate surface. The ability of Ge disk lattices on Si substrates to alter the light propagation direction could become an effective tool for coupling light into an optical waveguide.

Facilitated by complex interactions in a nonlinear dissipative system, solitons can be bound as particle-like structures (“soliton molecules”), with potential applications in biomedical imaging, data coding storage, high-capacity optical communications, and so on. Here, we demonstrate a flexible control of diversiform bound states formation in an all-polarization-maintaining mode-locked fiber laser via direct manipulation of the additional phase bias in the cavity. Adjusting the waveplate orientation in a nonreciprocal phase shifter provides different additional phase biases for both orthogonally polarized light signals, and the changed asymmetry of nonlinear amplifying loop mirror induces the variation of the nonlinear phase-shift difference between the clockwise and counterclockwise directions, programming the formation of soliton molecules (SMs) and SM complexes with different dynamics patterns. More importantly, this straightforward approach allows for switching between single-soliton and dual-soliton molecule or triple-soliton molecule under appropriate small-signal gain. The findings offer novel approaches for an in-depth understanding of the nonlinear soliton interaction mechanism and the generation of reconfigurable soliton molecules in ultrafast science.

We present an approach for retrieving dark-field, phase-shift, and attenuation images from speckle-based x-ray imaging data. Speckle-based x-ray imaging (SBXI) exploits sample-induced alterations to a reference near-field speckle pattern produced by a randomly structured mask. Attenuation images allow materials of different densities to be visualized. Phase-shift images are useful because they reveal how materials in a sample refract the x-ray beam, providing contrast between similar low-density structures that are difficult to reconstruct in attenuation images. Dark-field images convey information about structures that are smaller than the spatial resolution and are thus invisible in both attenuation and phase-shift images. In previous works, we presented the multimodal intrinsic speckle-tracking (MIST) algorithm, which recovers the three complementary images from SBXI data by solving the associated x-ray Fokker-Planck equation. In this work, we present a variation of MIST, which we call “gradient-flow MIST,” which (1) reduces the amount of SBXI data required for image retrieval, (2) maintains the full generality of the x-ray Fokker-Planck equation, and (3) recovers dark-field images with higher quality than the previously proposed variants for weakly attenuating (i.e., low density) samples. We demonstrate the new gradient-flow MIST approach on experimental SBXI data of a knotted bundle of carbon fibers acquired at the Australian synchrotron. This approach is anticipated to be useful in phase-contrast and dark-field applications that require simplicity in experimentation and low sample x-ray exposure.

Quantum dot molecules (QDMs), with their unique optoelectronic properties derived from quantum confinement and tunneling effects, are not only promising for advanced photonic applications but also provide the intrinsic advantage of nanoscale dimensions, which is critical for integrated miniaturized devices. In this work, we propose a scheme to realize a high-intensity two-dimensional asymmetric electromagnetically induced diffraction grating in a QDMs system by incorporating spontaneously generated coherence (SGC) and dual tunneling channels. Our theoretical analysis shows that the presence of SGC markedly enhances the intensity and efficiency of higher-order diffractions. Furthermore, by adjusting the orbital angular momentum and beam waist of vortex beams, we not only amplify the disparity in asymmetric diffraction and enhance the efficiency of the third-order diffraction peak, but also enable a lossless spatial interchange between the diffraction peak positions and those at symmetric positions solely by reversing the orbital angular momentum direction. Additionally, tuning the interdot tunneling strength increases the maximum third-order diffraction intensity by three orders of magnitude, reaching an intensity that is more than ten times higher than the third-order diffraction intensity observed at symmetric positions. These results, which fully leverage the nanoscale advantage and tunable characteristics of QDMs, offer a solid foundation for the implementation of compact photonic devices and pave the way for potential applications in optical diffractive neural networks and electromagnetically induced quantum holography.

In contrast to the general argument that the spontaneous decay is intrinsically incoherent in nature and harmful to entanglement, here, we show that nearly perfect entanglement between two bright pump fields can be realized via spontaneous decay-induced destructive quantum interference in a closed double Λ-type four-level system with the energy separation of the excited doublet comparable to their decay rates. The high degree of bipartite entanglement results from the cancellation of spontaneous emission and subsequent elimination of the associated noise due to the destructive quantum interference between the two spontaneous emission pathways from the upper doublet to each of the two lower levels when the two strong pump fields are tuned to the particular frequencies where quantum interference takes place. This scheme is particularly suitable for the generation of entanglement between two bright light fields, and may find potential applications in realistic quantum information processing.

We present a systematic study of the properties of systems composed of $N$ two-level quantum emitters coupled to a single cavity mode, for light-matter interaction strengths ranging from the weak to the ultrastrong and deep-strong coupling regimes. Beginning with an analysis of the energy spectrum as a function of the light-matter coupling strength, we examine systems with varying numbers of emitters, from a pair to large collections, approaching the thermodynamic limit $(N\to \infty )$. Additionally, we explore the emission properties of these systems under incoherent excitation of the emitters, employing a general theoretical framework for open cavity-QED systems, which is valid across all light-matter interaction regimes and preserves gauge invariance within truncated Hilbert spaces. Furthermore, we study the influence of the emitter-environment interaction on the spectral properties of the system. Specifically, when each emitter interacts independently with its own reservoir, we observe the emergence of an emission peak at the cavity's resonant frequency for even values of $N$. Our analysis also clarifies the evolution of the system as the number of emitters increases, ultimately converging toward an equivalent system composed of two interacting single-mode bosonic fields.

We propose a protocol for generating photon-number entanglement through sequential parametric down-conversion processes. This protocol is fully compatible with linear optics experiments and can be easily implemented as an extension of the path-identity scheme. We present a detailed scheme for the creation of heralded two-mode photon-number high-dimensional entanglement with the form of $|00\rangle +|11\rangle +|22\rangle$. In addition, the protocol enables us to easily generate various photon-number-entangled states, which have potential applications in quantum communication, quantum precision measurements, and continuous-variable quantum information.

The recoherence times $t^{*}$ and the maximum values of the recoherence increments ${\gamma }_{\mathrm{extr}}$ are studied as functions of the bath parameters for a single qubit dephasing model, prepared initially by a special kind of the nonselective measurements. The recoherence-decoherence events (RDE), occurring at the initial stage of the system evolution, are found to be both similar and different from the system dynamics at large times. For instance, in contrast to the RDE observed on large timescales, the sub-Ohmic and Ohmic coupling regimes are more favorable for the short-time recoherence than the super-Ohmic one. On the other hand, the short-time behavior of the recoherence and the long-time dynamics of the decoherence are closely related: The domain of the ohmicity indexes, where the decoherence changes its type (from the complete to incomplete one), is, simultaneously, that of the weakest recoherence. The obtained results give us some hints about the basic characteristics of the environment, which might provide the most optimal values of $t^{*}$ and ${\gamma }_{\mathrm{extr}}$ in some sense.

We propose a modified non-Markovian quantum jump method to overcome the obstacle of dramatically increased trajectory number in conventional quantum trajectory simulations. In our method the trajectories are classified into the trajectory classes characterized by the number of quantum jumps. We derive the expression of the existence probability of each trajectory (class), which is essential to construct the density matrix of the open quantum system. This modified method costs less computational resources and is more efficient than the conventional quantum trajectory approach. As applications we investigate the dynamics of spin-$\frac{1}{2}$ systems subject to Lorentzian reservoirs with considering only the no-jump and one-jump trajectories. The revival of coherence and entanglement induced by the memory effect is observed.