We demonstrate that the shear phase introduced by a tilting Raman beam in a Mach-Zehnder atom interferometer actually shifts the absolute phase, and propose how this shift can be compensated for by reference to a special point of the interference fringe. In the experiment, we obtain shear interference fringes and achieve the extraction of absolute phase corresponding to gravity acceleration. To suppress the impact of position drift on measurement accuracy, we adopt a positive and negative tilt angle alternating measurement (PNTAM) method. After using this PNTAM method, when the position drift leads to a change of $2.2\times {10}^{-3}\mathrm{g}$, the impact of this drift on the absolute measurement value is less than $1.9\times {10}^{-4}\mathrm{g}$. This work expands the application range of the phase shear readout based atom interferometer from the current relative or differential gravity measurement to the field of absolute gravity measurement.

Turbulence in quantum fluids has, surprisingly, a lot in common with its classical counterpart. Recently, cold atomic gases has emerged as a well-controlled experimental platform to study turbulent dynamics. In this work, we introduce a system to study quantum turbulence in optics, with the major advantage of having access to a wide range of characterization tools available for light fields. In particular, we report the temporal dynamics of density and phase and we show the emergence of isotropy in momentum space and the presence of different scaling laws in the incompressible kinetic energy spectrum. The microscopic origin of the algebraic exponents in the energy spectrum is discussed by studying the internal structure of quantized vortices within the healing length and their clustering at larger length scales. These results are obtained using two counterstreaming fluids of light, which allows for a precise preparation of the initial state and the in situ measurement of the compressible and incompressible fluid velocity.

One of the main requirements for advanced optical systems is controllability, which can be greatly improved by introducing gain elements into a guiding system. In this study, we consider a coupled photonic-plasmonic system composed of a dielectric waveguide and a three-layer (dielectric-metal-dielectric) waveguide spaser with loss and gain. Conditions of mode degeneracy in this system are revealed. A classification of waveguide and surface plasmon modes is used to find parameters of the formation of exceptional points (EPs) of the coupled system with loss and gain. It is shown that at these points the lifting of the mode degeneracy occurs. In addition, the response of the coupled system to illumination is investigated for incident Gaussian beams of two orthogonal polarizations. It is demonstrated that the control of the incident beam polarization makes it possible to excite different modes. The revealed operation conditions of the optical system with two-stage control (control of the EP parameters plus control of wave polarization) can widen the application range of coupled spaser-dielectric waveguide systems.

Based on time-dependent variational-principle algorithms, we investigate the dynamical critical behavior of quantum three-state Potts chains with chiral interactions. Using the Loschmidt echo, dynamical order parameter, and entanglement entropy as an indicator, we show that as the chiral interaction $\theta$ increases, the first critical time $t_1^{*}$ shifts towards lower values, indicating a chirality-related dynamical phase transition. Moreover, we perform dynamical scaling for the Loschmidt echo and obtain the critical exponent $\nu$ at the nonconformal critical point. The results show that as the chiral interaction $\theta$ increases, the correlation-length exponent $\nu$ decreases, which is similar to the long-range interaction case. Finally, we give a simple physical argument to understand the above numerical results. This work provides a useful reference for further research on many-body physics out of equilibrium with chiral interaction.

Time crystals are nonequilibrium many-body phases in which the state of the system dynamically approaches a limit cycle. While these phases have recently been the focus of intensive research, it is still far from clear whether they can host quantum correlations. In fact, mostly classical correlations have been observed so far, and time crystals appear to be effectively classical high-entropy phases. Here, we consider the nonequilibrium behavior of an open quantum light-matter system, realizable in current experiments, which maps to a paradigmatic time-crystal model after an adiabatic elimination of the light field. The system displays a bistable regime with coexistent time-crystal and stationary phases, terminating at a tricritical point from which a second-order phase transition line departs. While light and matter are uncorrelated in the stationary phase, the time-crystal phase features bipartite correlations of both quantum and classical nature. Our work unveils that time-crystal phases in collective open quantum systems can sustain quantum correlations, including entanglement, and are thus more than effectively classical many-body phases.

We develop a framework to solve a large class of linearly driven non-Hermitian quantum systems. Such a class of models in the Hermitian scenario is commonly known as multistate Landau-Zener models. The non-Hermiticity is due to the anti-Hermitian couplings between the diabatic levels. We find that there exists a conservation law, unique to this class of models, that describes the simultaneous growth of the unnormalized wave functions. These models have practical applications in Bose-Einstein condensates, and they can describe the dynamics of multispecies bosonic systems. The conservation law relates to a pair-production mechanism that explains the dissociation of diatomic molecules into atoms. We provide a general framework for both solvable and semiclassically solvable non-Hermitian Landau-Zener models. Our findings will open alternative avenues for a number of diverse emergent phenomena in explicitly time-dependent non-Hermitian quantum systems.

The pure states that can be uniquely determined among all (UDA) states by their marginals are essential to efficient quantum state tomography. We generalize the UDA states from the context of pure states to that of arbitrary (whether pure or mixed) states, motivated by the efficient state tomography of low-rank states. The concept of additivity of $k$-UDA states for three different composite types of tensor product applies if the composite state of two $k$-UDA states is still uniquely determined by the $k$-partite marginals for the corresponding type of tensor product. We show that the additivity holds if one of the two initial states is pure and present the conditions under which the additivity holds for two mixed UDA states. One of the three composite types of tensor product is also adopted to construct genuinely multipartite entangled (GME) states. Therefore, it is effective to construct multipartite $k$-UDA states with genuine entanglement by uniting the additivity of $k$-UDA states and the construction of GME states.

We theoretically investigate the high-order harmonic generation (HHG) of zinc oxide (ZnO) induced by linearly polarized laser pulses. It is found that the harmonic spectrum exhibits fine subpeak structures, which is related to the interband polarization arising from electron-hole interactions. Further numerical analyses show that the subpeak structures originate from the interference between the interband harmonics, which are generated by different crystal momentum channels around the top of the valence band. Additionally, we extend our inquiry to solid HHG driven by a two-color laser field. Intriguingly, our findings indicate a notable suppression of harmonic subpeak structures in this context. To gain insight into the governing physical mechanisms, we illustrate the time-dependent population in the conduction band. Our analysis underscores a phenomenon of electron preacceleration before ionization. Consequently, the crystal momentum channels around the top of the valence band exhibit diminished contributions to HHG, leading to the effective suppression of harmonic subpeak structures. Our results may provide insights into the underlying mechanisms of solid HHG.

Thermal noise is a major obstacle to observing quantum behavior in macroscopic systems. To mitigate its effect, quantum optomechanical experiments are typically performed in a cryogenic environment. However, this condition represents a considerable complication in the transition from fundamental research to quantum technology applications. It is therefore interesting to explore the possibility of achieving the quantum regime in room-temperature experiments. In this work we test the limits of sideband-cooling vibration modes of a SiN membrane in a cavity optomechanical experiment. We obtain an effective temperature of a few millikelvins, corresponding to a phononic occupation number of around 100. We show that further cooling is prevented by the excess classical noise of our laser source, and we outline the road toward the achievement of ground state cooling.

We focused on investigating the trapping characteristics of the circular Pearcey beam (CPB) on Mie particles. To study the trapping performance of CPB on particles of different sizes, we employed the generalized Lorenz-Mie theory (GLMT) for analysis. Our results revealed that the CPB exhibits a stronger optical trapping force for a larger Mie particle. To validate our findings, we constructed an experimental setup of optical tweezers and demonstrated the enhanced trapping performance of the CPB for larger Mie particles. Moreover, we discovered that, compared to the conventional circular Airy beam with the same focusing length, CPB also presents a significantly better trapping performance. Finally, by adjusting the spatial distribution factor of the CPB, we can effectively control the trapping performance in optical manipulation. The relationship between the trapping force properties of the CPB and the spatial distribution factor can be formulated as an exponential function. Overall, our study provides valuable insights into the optical trapping potential of autofocusing beams, particularly the CPB. These findings open up different avenues for the development of photonic tools in the field of optical trapping and manipulation.

In the present paper we study the influence of the Coulomb potential on the real and imaginary parts of the plasma-induced susceptibility in a photoionized gas. We show that the real part of the susceptibility is more than one order of magnitude larger due to the action of a Coulomb potential. Surprisingly, the long-range Coulomb potential of the atomic core leads to an additional contribution to the imaginary part of the susceptibility which has no counterpart in the case of a short-range potential. We demonstrate that the origin of this behavior is electrons in states very close to the continuum (nearly free electrons), and analyze the dependence of the susceptibility on the intensity and wavelengths.

We report passive magnetic levitation and three-dimensional harmonic trapping of a 0.3-milligram, 0.5-millimeter-diameter yttrium iron garnet sphere at 4 K. The gradient of an external magnetic field is used for vertical trapping, while the finite-size effect of the diamagnetic effect is used for horizontal trapping. The dynamics of the levitated sphere was optically measured to have trapping frequencies of up to around 600 Hz and mechanical $Q$ factors of the order of $Q\sim {10}^3$. These results were quantitatively reproduced by three-dimensional finite-element method simulations. Our results can provide a system where magnetism, rigid body motions, microwaves, and optics interact.

We study counting photons confined in a mode of a microwave resonator via repeated measurements by a Josephson photomultiplier (JPM). The considered JPM is essentially a flux-biased phase qubit operating as a single-photon detector. We identify optimal operational regimes that maximize photon-number resolution within a predetermined range. Two counting techniques are studied. The first is to count the total number of clicks in the measurement sequence. The second involves counting the number of clicks until the occurrence of either the first no-click event or the end of the measurement sequence. Our theoretical methods employ the derived positive operator-valued measures for the considered photocounting techniques and the introduced measure of the photon-number resolution. The results reveal that the resolution decrease in both cases is mainly caused by the JPM relaxation. As an example, we show how the obtained results can be used for practical testing nonclassical properties of electromagnetic radiation in a microwave resonator.

Generalized probabilistic theories (GPTs) provide a framework in which a range of possible theories can be examined, including classical theory, quantum theory, and those beyond. In general, enlarging the state space of a GPT leads to fewer possible measurements because the additional states give stronger constraints on the set of effects, the constituents of measurements. This can have implications for information processing. In box world, for example, a GPT in which any no-signaling distribution can be realized, there is no analog of a measurement in the Bell basis and hence the analog of entanglement swapping is impossible. A comprehensive study of measurements on multiple systems in box world has been lacking. Here we consider such measurements in detail, distinguishing those that can be performed by interacting with individual systems sequentially (termed wirings), and the more interesting set of those that cannot. We compute all the possible box-world effects for cases with small numbers of inputs, outputs, and parties, identifying those that are wirings. The large state space of box world leads to a small effect space and hence the effects of box world are widely applicable in GPTs. We also show some possible uses of nonwirings for information processing by studying state discrimination, nonlocality distillation, and the box-world analog of nonlocality without entanglement. Finally, we connect our results to the study of logically consistent classical processes and to the composition of contextuality scenarios. By enhancing understanding of measurements in box world, our results could be useful in studies of possible underlying principles on which quantum theory can be based.

We experimentally investigate nonlocal contextual relations between complementary photon polarizations by adapting the entanglement and the local polarizations of a two-photon state to satisfy three deterministic conditions demonstrating both quantum contextuality and nonlocality. The key component of this adaptive input state control is the variable degree of entanglement of the photon-pair source. Local polarization rotations can optimize two of the three correlations, and the variation of the entanglement optimizes the third correlation. Our results demonstrate that quantum contextuality is based on a nontrivial trade-off between local complementarity and quantum correlations.

We systematically study a set of strongly polar heteronuclear diatomic molecules composed of laser-coolable atoms for their suitability as sensitive probes of new charge-parity violation in the hadron sector of matter. Using relativistic general-excitation-rank configuration-interaction theory we single out the molecule francium-silver (FrAg) as the most promising system in this set and calculate its nuclear Schiff-moment interaction constant to $W_{\text{SM}}^{\mathrm{FrAg}}\left(\mathrm{Fr}\right)=30168\pm 2504\text{a.u.}$ for the target nucleus Fr. Our work includes the development of system-tailored atomic Gaussian basis sets for the target atom in each respective molecule.

The confined variational method is used to study the elastic scattering of the positron from the ground-state helium with the scattering energy in the range from 0.05 eV to 11.02 eV. Describing the correlation effect with explicitly correlated Gaussians, we obtain accurate phase shifts, $S$-wave scattering length, elastic scattering cross sections, and annihilation parameters for different incident momenta. Specifically, by a least-squares fit of the data to the effective-range theory, we determine the room temperature annihilation parameter $Z_{\mathrm{eff}}=3.955$, which is in perfect agreement with the measured result of $3.94\pm 0.02$ [J. Phys. B 8, 1734 (1975)].

Wave-particle duality, as complementarity displayed in interferometry, has been investigated extensively from both theoretical and experimental perspectives. In this work, we quantify coherence in multipath interference via quantum Fisher information and illuminate its basic properties. We prove that any rational quantifier of coherence satisfying monotonicity under incoherent operations is nonincreasing in the presence of path detectors. This quantitatively implies that increase on the path information will lead to the loss of coherence or interference (wave feature), which is consistent with wave-particle duality. Furthermore, we provide an operational illustration of wave feature as quantum Fisher information of phase shift parameters encoded in each interference path. By dividing the variance of a quantum state relative to a von Neumann measurement into quantum uncertainty and classical uncertainty, we establish a coherence-predictability-correlations triality relation, with coherence (wave feature) quantified by quantum Fisher information, predictability quantified by purity of a classical probability distribution, and correlations quantified by classical uncertainty relative to the von Neumann measurement determined by the interference paths. Finally, we make a comparison between this triality relation and the wave-particle-mixedness triality relation in the literature.