Search Results (61)

The wave–particle duality is the quintessence of quantum mechanics. This duality gives rise to distinct behaviors depending on the experimental setup, with the system exhibiting either wave-like or particle-like properties, depending on whether the focus is on interference (wave) or trajectory (particle). In the interaction with a beam splitter, photons with particle behavior can transform into a wave behavior and vice versa. In Wheeler’s delayed-choice gedanken experiment, this interaction is delayed so that the wave that initially travels through the interferometer can become a particle, avoiding the interaction. We show that this contradiction can be resolved using polarized entangled photon pairs. An analysis of Shannon’s entropy supports this proposal. Full article

Entangled multiphoton is an ideal resource for quantum information technology. Here, narrow-bandwidth hyper-entangled quadphoton is theoretically demonstrated by quantizing degenerate Zeeman sub states through spontaneous eight-wave mixing (EWM) in a hot ⁸⁵Rb. Polarization-based energy-time entanglement (output) under multiple polarized dressings is presented in detail with uncorrelated photons and Raman scattering suppressed. High-dimensional entanglement is contrived by passive non-Hermitian characteristic, and EWM-based quadphoton is genuine quadphoton with quadripartite entanglement. High quadphoton production rate is achieved from co-action of four strong input fields, and electromagnetically induced transparency (EIT) slow light effect. Atomic passive non-Hermitian characteristic provides the system with acute coherent tunability around exceptional points (EPs). The results unveil multiple coherent channels (~8) inducing oscillations with multiple periods (~19) in quantum correlations, and high-dimensional (~8) four-body entangled quantum network (capacity ~65536). Coexistent hyper and high-dimensional entanglements facilitate high quantum information capacity. The system can be converted among three working states under regulating passive non-Hermitian characteristic via triple polarized dressing. The research provides a promising approach for applying hyper-entangled multiphoton to tunable quantum networks with high information capacity, whose multi-partite entanglement and multiple-degree-of-freedom properties help optimize the accuracy of quantum sensors. Full article

Paeonia ludlowii is a threatened and valuable germplasm in the cultivated tree peony gene pool, with distinctive traits such as tall stature, pure yellow flowers, and scarlet foliage in autumn. However, the crossability barrier limits gene transfer from P. ludlowii to cultivated tree peony. Therefore, our study investigated the reasons for the lack of crossability between P. ludlowii and Paeonia ostii ‘Fengdan’. Distant cross pollination (DH) resulted in the formation of many calloses at the ends of the pollen tubes, which grew non-polar, twisted, entangled, and often stopped in the style. Pollen tubes elongated the fastest in self-pollination (CK), and pollen tubes elongated faster and fewer pollen tube abnormalities were observed in stigmas treated with KCl solution before pollination (KH) than in DH. During pollen–pistil interactions, the absence of stigma exudates, high levels of H₂O₂, O₂⁻, MDA, ^•OH, ABA, and MeJA, and lower levels of BR and GA₃ may negatively affect pollen germination and pollen tube elongation in the pistil of P. ostii ‘Fengdan’. Pollen tubes in CK and KH penetrated the ovule into the embryo sac at 24 h after pollination, whereas only a few pollen tubes in DH penetrated the ovule at 36 h after pollination. Pre-embryo abnormalities and the inhibition of free nuclear endosperm division resulted in embryo abortion in most of the fruits of DH and many fruits of KH, which occurred between 10 and 20 days after pollination, whereas embryos in CK developed well. Early embryo abortion and endosperm abortion in most of the fruits of DH and KH led to seed abortion. Seed abortion in KH and DH was mainly due to an insufficient supply of auxins and gibberellins and lower content of soluble protein and soluble sugars. The cross failure between P. ludlowii and P. ostii ‘Fengdan’ is mostly caused by a pre-fertilization barrier. KH treatment can effectively promote pollen tube growth and facilitate normal development of hybrid embryos. These findings provide new insights into overcoming the interspecific hybridization barrier between cultivated tree peony varieties and wild species. Full article

Quantum key distribution (QKD) is a cornerstone of secure communication in the quantum era, yet most existing protocols are designed for point-to-point transmission, limiting their scalability in networked environments. In this work, we introduce Loop-Back QKD, a novel QKD protocol that supports both two-party linear configurations and scalable multiuser ring topologies. By leveraging a structured turn-based mechanism and bidirectional pulse propagation, the protocol enables efficient key distribution while reducing the quantum bit error rate (QBER) through a multi-pulse approach. Unlike trusted-node QKD networks, Loop-Back QKD eliminates intermediate-node vulnerabilities, as secret keys are never processed by intermediate nodes. Furthermore, unlike Measurement-Device-Independent (MDI-QKD) and Twin-Field QKD (TF-QKD), which require complex entanglement-based setups, Loop-Back QKD relies solely on direct polarization transformations, reducing vulnerability to side-channel attacks and practical implementation challenges. Additionally, our analysis indicates that multi-pulse Loop-Back QKD can tolerate higher QBER thresholds. However, this increased robustness comes at the cost of a lower key rate efficiency compared to standard QKD schemes. This design choice enhances its robustness against real-world adversarial threats, making it a strong candidate for secure multiuser communication in local and metropolitan-scale quantum networks. Full article

With the advancement of non-classical light sources such as single-photon and entangled-photon sources, innovative microscopy based on quantum principles has been proposed for traditional microscopy. This paper introduces the experimental demonstration of a quantum polarization microscopic technique that incorporates a quantum-entangled photon source. Although the point that employs the variation in polarization angle due to reflection or transmission at the sample is similar to classical polarization microscopy, the method for constructing the image contrast is significantly different. The image contrast is constructed by the coincidence count of signal and idler photons. In the case that the coincidence count is recorded from both the signal and idler photons, the photon statistics resemble a thermal state, similar to the blackbody radiation, but with a significantly higher peak intensity in the second-order autocorrelation function at zero delay that is derived from the coincidence count, while, when the coincidence count is taken from either the signal or idler photon only, although the photon state exhibits a thermal state again, the photon statistics become more dispersive and result in a lower peak intensity of the autocorrelation function. These different thermal states can be switched by slightly changing the photon polarization, which is suddenly aroused within a narrow range of the analyzer angle. The autocorrelation function g²(0) at the thermal state exhibits a sensitivity that is three times higher compared to the classical coincidence count rate, and this concept can be effectively utilized to enhance the contrast of the image. One of the key achievements of our proposed method is ensuring a low power of illumination (in the order of Pico-joules) for constructing the image. In addition, the robustness without any precise setup is also favorable for practical use. This polarization microscopic technique can provide a superior imaging technique compared to the classical method, opening a new frontier for research in material sciences, biology, and other fields requiring high-resolution imaging. Full article

Instrument reading detection in industrial scenarios poses significant challenges due to reading contour distortion caused by perspective transformation in the instrument images. However, existing methods fail to accurately read the display automatically due to incorrect labeling of the target box vertices, which arises from the vertex entanglement problem. To address these challenges, a novel Quadrilateral Contour Disentangled Detection Network (QCDNet) is proposed in this paper, which utilizes the quadrilateral disentanglement idea. First, a Multi-scale Feature Pyramid Network (MsFPN) is proposed for effective feature extraction to improve model accuracy. Second, we propose a Polar Coordinate Decoupling Representation (PCDR), which models each side of the instrument contour using polar coordinates. Additionally, a loss function for the polar coordinate parameters is designed to aid the PCDR in more effectively decoupling the instrument reading contour. Finally, the experimental results on the instrument dataset demonstrate that QCDNet outperforms existing quadrilateral detection algorithms, with improvements of 4.07%, 1.8%, and 2.89% in Precision, Recall, and F-measure, respectively. These results confirm the effectiveness of QCDNet for instrument reading detection tasks. Full article

Multilevel charge pumping is a feature that was recently observed in quasiperiodic systems. In this work, we show that it is more generic and appears in different aperiodic systems. Additionally, we show that for aperiodic systems admitting arbitrarily long palindromic factors, the charge pumping protocol connects two topologically distinct insulating phases. This confirms the existence of topological phases in aperiodic systems whenever their finite-size realizations admit inversion symmetry. These phases are characterized by an anomalous edge response resulting from the bulk–boundary correspondence. We show that these signatures are all present in various chains, each representing a different class of structural aperiodicity: the Fibonacci quasicrystal, the Tribonacci quasicrystal, and the Thue–Morse chain. More specifically, we calculate three quantities: the Berry phase of the periodic approximation of the finite-size systems, the polarization response to an infinitesimal static and constant electric field in systems with open boundary conditions, and the degeneracy of the entanglement spectrum. We find that all of them provide signatures of a topologically nontrivial phase. Full article

Quantum heat engines (QHEs) are established by applying the principles of quantum thermodynamics to small−scale systems, which leverage quantum effects to gain certain advantages. In this study, we investigate the quantum Otto cycle by employing the dipole−dipole coupled polar molecules as the working substance of QHE. Here, the molecules are considered to be trapped within an optical lattice and located in an external electric field. We analyze the work output and the efficiency of the quantum Otto heat engine (QOHE) as a function of various physical parameters, including electric field strength, dipole−dipole interaction and temperatures of heat baths. It is found that by adjusting these physical parameters the performance of the QOHE can be optimized effectively. Moreover, we also examine the influences of the entanglement and relative entropy of coherence for the polar molecules in thermal equilibrium states on the QOHE. Our results demonstrate the potential of polar molecules in achieving QHEs. Full article

Since methods for reducing macromolecule entanglements have been developed, it has become possible to better understand the impact of polymer chain entanglement on the crystallization process. The article presents basic information about the disentangling of macromolecules and the characterization of the degree of entanglement. The basic knowledge of polymer crystallization was also presented. Then, it was discussed how polymers crystallize during their disentangling. Non-isothermal and isothermal crystallization experiments using disentangled polymers, and for comparison using entangled polymers, are described in more detail. The influence of disentangling on both nucleation and crystal growth is highlighted. It is also shown how the crystallization of polymers changes when macromolecules re-entangle. Full article

Single-layer transition-metal dichalcogenides provide an unique intrinsic entanglement between the spin/valley/orbital degrees of freedom and the polarization of scattered photons. This scenario gives rise to the well-assessed optical dichroism observed by using both steady and time-resolved probes. In this paper, we provide compact analytical modeling of the onset of a finite Faraday/Kerr optical rotation upon shining with circularly polarized light. We identify different optical features displaying optical rotation at different characteristic energies, and we describe in an analytical framework the time-dependence of their intensities as a consequence of the main spin-conserving and spin-flip processes. Full article

Polarization-sensitive quantum optical coherence tomography (PS-QOCT) is used to image and characterize birefringence effects in biological samples. Entangled photons are generated via spontaneous parametric down-conversion and split into a reference arm and a sample arm of a Mach Zehnder interferometer. Interferometric patterns between two entangled photons reveal information about tissue birefringence. Biological tissue samples are imaged and characterized, and their quantum interference patterns and birefringence profiles are presented. Full article

Many quantum device signals are proportional to the number of the participating atoms that take part in the detection devices. Among these are optical magnetometers, atomic clocks, quantum communications and atom interferometers. One way to enhance the signal-to-noise ratio is to introduce atom entanglement that increases the signal in a super-radiant-like effect. A coherent em field inside a laser cavity is suggested to achieve atoms’ correlation/entanglement. This may also play an important role in the basic quantum arena of many-body physics. An initial novel experiment to test the realization of atoms’ correlation is described here. A Cs optical magnetometer is used as a tool to test the operation of a cell-in-cavity laser and its characteristics. A vapor cell is inserted into an elongated external cavity of the pump laser in Littrow configuration. Higher atom polarization and reduced laser linewidth are obtained leading to better magnetometer sensitivity and signal-to-noise ratio. The Larmor frequency changes of the Free Induction Decay of optically pumped Cs atomic polarization in the ambient earth magnetic field at room temperature is measured. Temporal changes in the magnetic field of less than 10 pT/√Hz are measured. The first-order dependence of the magnetic field on temperature and temperature gradients is eliminated, important in many practical applications. Single and gradiometric magnetometer configurations are presented. Full article

Traditional Hong-Ou-Mandel (HOM) interferometry, insensitive to photons phase mismatch, proved to be a rugged single-photon interferometric technique. By introducing a post-beam splitter polarization-dependent delay, it is possible to recover phase-sensitive fringes, obtaining a temporal quantum eraser that maintains the ruggedness of the original HOM with enhanced sensitivity. This setup shows promising applications in biological sensing and optical metrology, where high sensitivity requirements are coupled with the necessity to keep light intensity as low as possible to avoid power-induced degradation. In this paper, we developed a highly sensitive single photon birefringence-induced delay sensor operating in the telecom range (1550 nm). By using a temporal quantum eraser based on common path Hongr-Ou-Mandel Interferometry, we were able to achieve a sensitivity of 4 as for an integration time of $2·{10}^4$ s. Full article

Vortex beams with helical phase wavefronts have recently emerged as a research hotspot because of their widespread applications such as ultra-high dimensional information encoding, quantum entanglement, and data transmission due to their unique properties. Research, as of yet, on the easy preparation of vector vortex beams is hindered by technical bottlenecks such as large mechanical modulation errors and limited bandwidths of meta-structured devices in spite of the massive experimental and theoretical breakthroughs in the generation of vortex beams that have been made. To make up for the deficiency in this area, we propose here a broadband vortex beam modulating system based on electrically controlled liquid crystal (LC) devices. An electrically controlled LC q-plate and an LC broadband polarization grating (PG) are integrated in the system as the crux devices. The system enables pure vortex-phase modulation within a wide spectral range in the visible spectrum and electrical control on the output beam intensity of the vortex and Gaussian components. Experiments at different voltages of 533 nm and 632.8 nm were conducted for validation. This system overcomes the complexity and stringent optical path requirements of traditional methods for generating vortex beams, offering an efficient, convenient, and rapidly tunable approach for generating vortex beams that is easily and highly integrable. Full article

A protocol for realizing discrete-variable quantum teleportation in an optomagnonic system is provided. Using optical pulses, an arbitrary photonic qubit state encoded in orthogonal polarizations is transferred onto the joint state of a pair of magnonic oscillators in two macroscopic yttrium-iron-garnet (YIG) spheres that are placed in an optical interferometer. We further show that optomagnonic entanglement swapping can be realized in an extended dual-interferometer configuration with a joint Bell-state detection. Consequently, magnon Bell states are prepared. We analyze the effect of the residual thermal occupation of the magnon modes on the fidelity in both the teleportation and entanglement swapping protocols. The work may find applications in the study of macroscopic quantum states, quantum information processing, and hybrid quantum networks based on magnonics. Full article