Abstract Nonlocal advantage of quantum coherence (NAQC) characterizes the nonlocal property of a bipartite system. We investigate NAQC in the thermal state of a double-quantum-dot system for which there are adjustable parameters such as the interdot energy detuning, the tunneling coupling, and the externally applied transverse and longitudinal magnetic fields. We identified the parameter regions in which NAQC exists for different cases, and showed that a small interdot energy detuning, a moderate tunneling coupling, and finite but not very strong transverse and longitudinal magnetic fields are beneficial for generating NAQC in this system.
Abstract We propose a protocol for nonadiabatic holonomic quantum computation based on squeezed cat states. By exponentially enhancing the Kerr nonlinearity of a harmonic oscillator via a tailored driving scheme, we enable the fast, nonadiabatic generation of squeezed coherent states through shortcuts to adiabaticity. These squeezed coherent states serve as the building blocks for squeezed cat states, which are then utilized as logical qubits in our holonomic framework. Numerical simulations show that our state-preparation mechanism is approximately five times faster than conventional adiabatic approaches, thereby providing a practical route to accelerate the realization of holonomic gates. Leveraging the robustness of geometric phases and the nonclassical features of squeezed cat states, our scheme offers a promising platform for high-speed, fault-tolerant quantum computation.
We demonstrate a single-stage gas-filled multi-pass cell system achieving a compression factor of 29. In this post-compression scheme, 0.94 mJ, 600 fs pulses are compressed to 20.8 fs with an output energy of 0.87 mJ. This system offers a robust and scalable platform for strong-field physics and high-harmonic generation driven by Yb-based ultrashort laser sources.
Vortex beams carry unique orbital angular momentum (OAM) and show great potential in target recognition and azimuth measurement. However, in practical scenarios, scattering media such as cloud and fog disturb their intensity, phase, and OAM spectra, thereby limiting their applications in complex environments. To address the difficulty of traditional Monte Carlo (MC) methods in obtaining optical field information and the low computational efficiency of the particle-screen method, this study proposes a vortex beam transmission model in cloud and fog based on the Fast electric-field Monte Carlo (FEMC) method. By incorporating optical field tracking into the traditional MC framework and introducing a preconstructed particle parameter pool for rapid parameter retrieval, the proposed method improves simulation efficiency. Based on this method, the evolution of the intensity, phase, and OAM spectra of vortex beams under different transmission distances, visibilities, topological charges and beam waist radii are investigated, and quantitative evaluations are conducted using the peak signal-to-noise ratio (PSNR) and OAM spectrum purity. The results show that, as the transmission distance increases, intensity diffusion, phase distortion, and OAM spectral crosstalk become more severe. As visibility increases, both PSNR and OAM spectrum purity improve significantly, indicating that the spatial structure and modal characteristics can be preserved more effectively under weaker scattering conditions. Under strong cloud and fog scattering conditions, the OAM spectrum distribution of lower-order vortex beams can be better preserved. The proposed FEMC method provides an effective tool for characterizing the optical field evolution and OAM spectral variations of vortex beams in scattering media, offering theoretical and simulation support for related studies and applications in complex environments.
Abstract This paper presents a high-performance mid-infrared laser and its application in spectroscopic gas detection. A ring-cavity continuous-wave optical parametric oscillator (OPO) based on MgO:PPLN was constructed, with a signal wavelength tuning range covering 1.3–1.9 μ m and an idler wavelength tuning range covering 2.4–4.7 μ m. The linewidth reached the MHz level, while the wavelength and power stability reached the pm level and below 1.3% RMS, respectively. Utilizing cantilever-enhanced photoacoustic spectroscopy to detect photoacoustic signals induced by periodically amplitude-modulated light, sensitive detection of CO₂ and CH₄ over a wide wavelength range was achieved, with a detection sensitivity reaching the sub-ppb level. The results indicate significant application prospects for high-performance OPOs in gas detection.
Abstract This study investigates the possibility of realizing a relativistic strophotron free electron laser (RS FEL) with a special focus on the stability of electron motion in such systems. As a hard problem, the FEL problem presents the challenge of creating electromagnetic tunable coherent radiation in a wide wavelength range, especially in the THz and x-ray ranges. This paper deals with the realization of a relativistic strophotron FEL. The optimal configuration of magnets has been identified, which achieves stable movement of electrons in relativistic strophotron. The results are applied to the periodicity of beam motion in both transverse directions to achieve the conditions for RS FEL realization. The research findings suggest that using a special configuration of magnets can contribute to the optimization of the relativistic strophotron making movement of an electron beam, which is stable and useful for the creation of RS FEL. We highlight the creation of an RS FEL, compare it with the usual undulator (see below) and point out the advantage of an RS FEL under certain conditions. A scheme with quadrupole lenses is presented for the realization of a relativistic strophotron type free electron laser. The presented scheme provides electron stability in the transversal direction. The equations of motion are solved and the trajectories are found. It is shown that the motion of electrons in the proposed scheme is stable in both transverse directions.
The conversion of photonic qubits between different physical encodings is a necessary condition for the creation of hybrid quantum networks. We propose and demonstrate a network scheme for a photonic qubit state converter from phase-frequency to polarization encoding, implemented in a Sagnac loop topology over a distance of 25 km. The obtained results of photonic qubit conversion with a fidelity of (0.99 +/- 0.01) open up the possibility of creating photonic qubit converters that are more resistant to external noise and can be integrated into a subcarrier wave quantum communication network with independent detection.
The survey discusses the problem of measuring correlations in composite quantum and statistical systems. After briefly recalling the standard methods of describing correlations, the emphasis is on the method of correlation indices. The latter method for quantifying the strength of correlations in composite physical systems is sufficiently general allowing for measuring in a unique way the correlation strength in both quantum and statistical systems, for static as well as for dynamic processes. The correlation indices, can be defined for correlation operators, reduced density matrices, and other operators containing information on correlations in the studied composite systems. The correlation indices measure all types of correlations, quantum correlations, such as entanglement, as well as classical correlations. They are applicable for characterizing static as well as dynamical processes. Examples are given of correlation indices for several quantum states and for spin and pseudospin systems. The quantification of correlations in a nonequilibrium system is exemplified by calculating the correlation index for a trapped Bose–Einstein condensate subject to the action of an alternating field.
We investigate the generation of quantum steering and nonlocality in a two-qubit system mediated by a one-dimensional plasmonic waveguide, with the qubits initially prepared in the ground state. Our results show that forward-asymmetric driving fields are particularly effective in generating quantum steering, producing higher peak values and an extended temporal duration compared to symmetric or reverse-driving cases. In addition, we find that quantum nonlocality can be generated under configurations where one forward-driving and one reverse-driving field are applied with unequal strengths. We determine the distinct optimal coupling strengths for maximizing transient steerability and steady-state steerability respectively, which may be beneficial for experimental implementation. Interestingly, a comparison between different initial qubit states (the ground state and maximally entangled state) shows that initial entanglement is not necessary for achieving steady-state steering, as both states produce nearly identical outcomes.
In co-fiber communication systems transmitting classical and quantum signals, the quantum information carried by a single photon is easily affected by phase noise in the fiber, leading to quantum state distortion. Traditional fixed control methods cannot respond promptly to this constantly changing interference. To address this, this paper proposes a lightweight, physically constrained quantum control framework. This framework uses physics-informed neural networks as its core to achieve adaptive compensation for time-varying noise. The model can be efficiently deployed on a Raspberry Pi, and in single-qubit manipulation tasks, its average fidelity is significantly better than baseline methods without physical constraints, while the performance on the Raspberry Pi is highly consistent with that on traditional platforms. This work provides a real-time, reliable, and low-power control path for co-fiber quantum communication.
This study aimed to evaluate the effects of photobiomodulation (PBM) using a low-power infrared laser on the expression of nucleotide excision repair (NER) genes in experimental model of arthritis. An articular inflammatory process was performed through the zymosan administration into the talocrural and subtalar joint regions of C57BL/6 mice. The animals were distributed (n = 5): Control (untreated); zymosan (untreated arthritic group); and zymosan + PBM, subdivided according to the laser fluence, and time point of analysis (24, 48, and 72 h). After 5 h, joint regions were exposed to a low-power infrared laser (830 nm, 3 or 30 J cm-2, 0.15 and 1.5 J, 10 mW, 200 mW cm-2) and following by daily PBM sessions. The ERCC1 and XPC mRNA relative levels were quantified using reverse transcription quantitative polymerase chain reaction (RT-qPCR) at 24, 48, and 72 h after arthritis induction. Results showed that zymosan-induced arthritis alone did not significantly alter the ERCC1 and XPC mRNA relative levels. However, PBM significantly reduced the expression of both genes at 24 and 48 h. Such downregulated effect was time-dependent, with gene expression levels returning to control values by 72 h. The results indicate that PBM, but not the zymosan-induced arthritis model itself, modulates NER-related gene expression. Downregulation of ERCC1 and XPC genes in a time-dependent manner suggests that low-power infrared laser therapy can alter global genome repair mechanisms in tissues affected by acute inflammation.
Graded-index multimode fibers demonstrate nonlinear effects that have no analog in single-mode case, such as Kerr Beam self-cleaning, Raman cleaning, etc. These effects were observed under random initial conditions i.e. modal content at the input of the fiber. The nonlinear dynamics of individual modes (Laguerre-Gaussian (LG) modes) when propagating in a graded-index fiber is of particular interest. This work is devoted to this issue: using an effective light structuring method, we discovered a novel nonlinear effect-stabilization of LG beams. We captured beam intensity profiles at the output of the fiber under different initial conditions in both CW and femtosecond pulse regime. Mode decomposition experiments approve that the contribution of initial group of degenerate modes increases dramatically after switching from linear to nonlinear propagation.
Optical skyrmions are topologically robust quasi-particles manifested as light-field structures with non-trivial topological characteristics, typically engineered by tailoring electromagnetic or other vectorial optical fields. Owing to their small size, high density, and diverse yet stable topological textures, these light-field configurations have attracted intense interest for applications in polarization-resolved imaging, high-density information storage and transmission, precision metrology. In this work, we report the generation of high-peak-power optical skyrmions based on a Q-switched pulsed laser system. Two orthogonally polarized pulse trains are produced simultaneously from the laser resonator. One train is converted directly to a left- or right-handed circularly polarized Gaussian beam by a quarter-wave plate, while the other, after the same plate, passes through a vortex wave plate to become a right- or left-handed circularly polarized vortex beam carrying orbital angular momentum. Subsequent extra-cavity interference of these two beams yields first-order N & eacute;el-, Bloch-, and Anti-skyrmion textures. The resulting high-peak-power optical skyrmions enhance both storage density and transmission reach, offering a promising platform for next-generation optical communication systems.
Taking advantage of the phase transition characteristics of VO2, we designed and experimentally verified a 0.1 THz tunable metalens. This 24-mm-aperture metalens based on geometric phase can achieve transmission or reflection focusing as designed. It was fabricated at low cost by 3D printing of Al2O3 combined with magnetron sputtering of VO2. The measured focal length and full-width-at-half-maximum are in agreement with the simulation, providing a feasible solution for THz reconfigurable optics.
Quantum batteries, as an important energy storage system in the future, are of vital importance to practical applications. However, due to the interaction between the quantum battery system and the environment, the battery capacity will decline. Then how to increase the capacity of quantum batteries becomes crucial. In this paper, we propose a new scheme via a local bipartite projective measurement to enhance the quantum battery capacity (QBC). Initially, two Werner states are taken as the carriers of the quantum batteries. Performing a local bipartite projective measurement performed on the two initially Werner states, a final state as a new quantum battery carrier can be realized. It is found that the QBC in the final state can be larger than those in the two initial states. That is to say, the enhancement of QBC can be realized via the local bipartite projective measurement.
In this paper, we aim to introduce a new state called photon-subtracted-then-added squeezing-enhanced coherent state (PSASECS) by multiple photon subtraction and then addition to a squeezing-enhanced coherent state. We investigate the non-Gaussianity and nonclassicality of this new state in detail, including its Wigner function, sub-Poissonian statistics, Q-function, squeezing, and antibunching properties. The obtained results indicate that these non-Gaussian and nonclassical characteristics have been enhanced by appropriately changing between photon subtraction l and photon addition k. Additionally, the non-Gaussianity and nonclassicality of PSASECS are enhanced compared to cases involving only the addition or subtraction of photons. This demonstrates the importance of subtracting and then adding photons to the squeezing-enhanced coherent state, and introducing a significant state for application in quantum optics, particularly in mitigating phase noise fluctuations in quantum devices.
Using numerical simulation methods, this study investigates the optical properties of 532 nm laser light in seawater channels in the presence of common suspended particles. Based on the material structure analysis of the suspended particles and Mie theory, the Mie parameters of five types of suspended matter-sediment, bubbles, mineral particles, detritus, and algae-are calculated as functions of particle size. By coupling Mie theory with a lognormal particle size distribution function, a dynamic Monte Carlo method is proposed for real-time retrieval of scattering parameters during photon-medium interactions. Using this approach, the extinction effects of different suspended particles and the influence of particle size distribution parameters on laser underwater transmission are compared and analyzed. The results indicate that the attenuation of 532 nm laser light by sediment and bubbles is dominated by scattering, whereas mineral particles, detritus, and algae exhibit both scattering and absorption effects. The extinction effects of different suspended particles show stage-wise variations with transmission distance. Both the increase in the average geometric radius and changes in the standard deviation of the particle size distribution lead to nonlinear attenuation of the normalized detected power, with different sensitivities to the transmission distance. The methodology and findings of this study offer theoretical underpinning and a modeling tool for evaluating the performance of underwater optical systems.
This study presents a miniaturized mid- to long-wave infrared computational spectrometer based on metasurface filter arrays fabricated on silicon and germanium substrates. Using electron-beam lithography, we created multi-channel filters that leverage subwavelength amplitude control targeting the 2.5-6.5 mu m and 8-14 mu m bands. Two computational spectral reconstruction methods were demonstrated based on a deep neural network algorithm: a portable approach using a thermal camera for the 8-14 mu m band, and Fourier-transform infrared-based method simulating single-pixel detection. Experimental results on materials such as cellophane and glass confirmed effective recovery of spectral features, demonstrating that the proposed metasurface filters combined with computational reconstruction can enable cost-effective, integrated computational reconstruction spectrometers.
Electromagnetically induced transparency (EIT) is an atomic coherence effect. The asymmetry of EIT signal has been found on experiment. Based on the ladder-type three-level system 6S1/2 -> 6P3/2 -> nD5/2 without considering the degenerate excited state, a four-level atomic system can be obtained by introducing the degenerate level nD3/2 of Rydberg state, and the influence of degenerate level on the EIT absorption curve is theoretically studied. The results show that the principal quantum number n has little effect on the population of different energy levels, but has great effect on the absorption curve of the probe laser. At the same time, we use the height ratio of wave crest (trough) to describe the asymmetry. Under the definite principal quantum n, we find that the Rabi frequency of probe laser is positively correlated with the asymmetry of absorption curve. The Rabi frequency of the coupling laser is also positively correlated with the asymmetry of the absorption curve.
Quantum entanglement is a fundamental resource in quantum information tasks. Schmidt number is a key quantity for characterizing the entanglement dimension of bipartite states. Constructing entanglement detection methods with physical interpretability and experimental feasibility is a current research focus. In this work, we utilize the geometric symmetry of the generalized equiangular measurement conical 2-design to derive a family of k-positive maps. Using the Choi-Jamio & lstrok;kowski isomorphism, we construct a general family of Schmidt number witnesses. For isotropic states, we derive a structure-independent analytical threshold. Our approach offers a mathematically concise criterion while retaining clear experimental feasibility.
