Science China Physics, Mechanics & Astronomy最新文献

In this paper, we investigate the electromagnetic form factors (EMFFs) and charge radii of pseudoscalar mesons within the light-front quark model (LFQM). Using parameters derived from the confinements of mesonic decay constants, we obtain numerical results, which indicate the following: (1) the EMFFs of charged and neutral mesons exhibit significant differences in their endpoint behaviors but show similar asymptotic behavior in the momentum transfer regions Q² > 2 GeV². For the EMFFs of light mesons such as π and K⁺, our results are in excellent agreement with experimental data in the small momentum transfer regions (Q² < 0.3 GeV²). For the charge radii of mesons, our results also show rough consistency with predictions from other approaches. (2) For charged mesons, the peak values of Q²F_P(Q²) are approximately proportional to the mass difference Δm between their constituent quarks. Moreover, the mean square radii 〈r²〉_P of charged mesons decrease with increasing meson mass and decreasing Δm. For neutral mesons, their charge radii are primarily determined by the electric charge of the heavy quark. These results indicate that quark mass asymmetry significantly influences the behavior of the EMFFs and charge radii of mesons. Experimental data to test these predictions would thus be of great interest.

Previously identified integrable boundary states in ABJM theory are exclusively achiral. This paper presents the first chiral integrable boundary states in the SU(4) alternating spin chain from the planar two-loop dilatation operator in the scalar sector. Utilizing a sufficient condition for the untwisted integrable condition, we identify specific two-site and four-site basis boundary states as chiral integrable states. Numerical evidence indicates that other basis states are unlikely to be chiral integrable. Furthermore, we compute the overlaps between these chiral integrable basis states and on-shell Bethe eigenstates.

Additively manufactured (AM) austenitic stainless steel (ASS, e.g., 316LSS) potentially exhibits excellent strength-ductility synergy in which the deformation-induced martensitic transformation (DIMT) is decisive. However, the DIMT mechanism is still elusive for AM 316LSS. Here we decipher the role of twin boundary (TB) and grain boundary (GB) in governing the DIMT behavior as well as the associated atomic-scale mechanism by characterization-informed atomistic simulations. Experimental characterizations of DIMT in AM 316LSS show martensite distributed near TBs under quasi-static (QS) tension, but closely related to GBs under high strain rate (HSR) tension. Informed by characterizations, atomistic models covering grain sizes, GB angles and TBs are then constructed to reveal the effect of GBs and TBs on DIMT behavior. It is found that the low-angle GB (LAGB) and small grain size in AM 316LSS suppress DIMT, whereas the synergistic effect of high-angle GB (HAGB) and large grain size (e.g., in wrought 316LSS) results in large-area DIMT. When TBs exist in the 316LSS grains, TBs can promote intragranular DIMT to make DIMT independent of GB angle and grain size, agreeing with DIMT observed in both wrought and AM 316LSS under QS tension. This is ascribed to the TBs-nearby heavy strain concentration that easily results in DIMT behavior and the TBs-nearby atoms that satisfy the Nishiyama-Wasserman relationship for triggering DIMT nucleation within the grain. In contrast, HAGBs dominate DIMT behavior in models without TBs owing to the GBs-nearby local lattice distortion that satisfies the Kurdjumov-Sachs relationship for allowing phase transformation. There are almost no HAGBs and thus an ignorable DIMT in AM 316LSS, agreeing with the experimental HSR tension results. These findings should shed light on the DIMT mechanism in AM 316LSS and help the design of AM 316LSS with improved mechanical performance.

Entanglement-enhanced quantum sensors encounter a fundamental trade-off: while entanglement improves precision to the Heisenberg limit, it restricts dynamic range. To address this trade-off, we present a credible-interval-based adaptive Bayesian quantum frequency estimation protocol for Greenberger-Horne-Zeilinger (GHZ)-state-based atomic clocks. Our method optimally integrates prior knowledge with new measurements and determines the interrogation time by correlating it with the period of the likelihood function, based on Bayesian credible intervals. Our protocol can be implemented using either individual or cascaded GHZ states, thereby extending the dynamic range without compromising Heisenberg-limited sensitivity. In parallel with the cascaded-GHZ-state protocol using fixed interrogation times, the dynamic range can be extended through an interferometry sequence that employs individual GHZ states with variable interrogation times. Furthermore, by varying the interrogation times, the dynamic range of the cascaded-GHZ-state protocol can be further extended. Crucially, our protocol enables dual Heisenberg-limited precision scaling ∝ 1/Nt in both particle number N and total interrogation time t, surpassing the hybrid scaling (infty 1/Nsqrt{t}) of the conventional cascaded-GHZ-state protocol. While offering a wider dynamic range, the protocol is more stable against noise and more robust to dephasing than existing adaptive schemes. Beyond atomic clocks, our approach establishes a general framework for developing entanglement-enhanced quantum sensors that simultaneously achieve both high precision and broad dynamic range.

Long-distance entanglement distribution is fundamental to the establishment of a large-scale quantum network, particularly in systems that operate without the need for trusted relays. Here, we demonstrate entanglement-based quantum key distribution over 343 km of fiber spools using multi-wavelength single-photon-level calibration light for reference frame alignment. By co-propagating calibration and entangled photons through identical paths and sharing detectors in a time-multiplexed manner, a polarization purity of 2783 achieves for two mutually unbiased bases. The system operates continuously for 27.1 h in the laboratory, generating a total of 253 bits secure key at an asymptotic secure key rate of 3.68 × 10⁻³ bps. This work provides a viable approach for constructing large-scale quantum network.

Organic micro-nanophotonics is an emerging interdisciplinary field that integrates photonics, nanoscience, and materials chemistry to explore light-matter interactions at the nanoscale. Compared with inorganic counterparts, organic materials offer distinct advantages such as high photoluminescence efficiency, tunable optical properties, and facile processability, which enable flexible and multifunctional nanophotonic applications. This review summarizes recent advances in organic nanophotonic materials and their applications in integrated photonic devices. First, we highlight the unique photophysical characteristics of typical organic materials—including small molecules, conjugated polymers, and hybrid systems—emphasizing their structural versatility and excited-state dynamics. Next, we discuss representative organic photonic devices such as lasers, photodetectors, OLEDs, photovoltaics, modulators, and optical coding systems, focusing on how organic components enhance device functionality. We further review recent progress in the design and fabrication of integrated organic photonic platforms, including patterning techniques, photonic integrated circuits (PICs), and nonlinear photonic systems. Finally, we outline the remaining challenges in the field and provide perspectives on future research directions, particularly in the rational molecular design and structure-property relationship of organic materials. By offering a comprehensive overview, this review aims to promote innovation in the development of tunable, high-performance nanophotonic devices based on organic materials.

Bulk-boundary correspondence is crucial for understanding topological insulators, as it indicates that nontrivial bulk topology can be revealed from the boundary response. However, not all topological insulators exhibit conventional energy or frequency boundary responses despite possessing a nontrivial bulk topology, which challenges the experimental probing of bulk topology. In this work, we utilize the entanglement spectrum, rather than the energy or frequency spectrum, for experimentally probing the bulk topology. We verify the bulk-entanglement spectrum correspondence in an acoustic multipole topological insulator even without the frequency boundary response. Our work provides a novel paradigm for probing the bulk topology and opens new avenues for exploring topological materials.

The recent discovery of high-T_c superconductivity in Ruddlesden-Popper (RP) nickelates has motivated extensive efforts to explore higher-T_c superconductors. Here, we systematically investigate Nd-doped La₃Ni₂O₇ using density functional theory (DFT) and renormalized mean-field theory (RMFT). DFT calculations reveal that both the lattice constants and interlayer spacing decrease upon Nd substitution, similar to the effect of physical pressure. However, the in-plane Ni-O-Ni bond angle evolves non-monotonically with doping, increasing to a maximum at 70% (∼2/3) Nd doping level and then falling sharply at 80%, which leads to a reduction in orbital overlap. Moreover, Nd doping has a more pronounced effect on the Ni-(d_{z^{2}}) orbital, demonstrating an orbital-dependent effect of rare-earth substitution. Through the bilayer two-orbital t-J model, RMFT analysis further shows an s_±-wave pairing symmetry, with T_c rising to a maximum at about 70% Nd substitution before declining, in agreement with the transport measurements. The variation in T_c can be traced to the competition between continuously enhanced interlayer (d_{z^{2}}) orbital hopping and a gradual decrease in electron density. These results highlight the delicate interplay among structural tuning, orbital hybridization, and superconductivity, providing important clues to design higher-T_c RP nickelate superconductors.

We propose a scheme to simultaneously achieve nonreciprocal unconventional and conventional photon blockade in a single photonic resonator based on the joint of chiral cavity-atom coupling and parametric amplification, which significantly enhances the nonreciprocal photon blockade (NPB) and is termed universal NPB. We demonstrate that the nonreciprocal unconventional photon blockade dominates in weak coupling regime characterized by chiral and backscattering couplings smaller than decay rate when driving the device from one side but not from the other side, whereas the nonreciprocal unconventional and conventional photon blockades simultaneously account for the NPB in the strong coupling regime. This broadens the parameter space of realizing the NPB and demonstrates a stronger NPB in the strong coupling regime. Furthermore, the nonreciprocity can be improved by approximately three orders of magnitude due to the presence of the parametric amplification. Our findings pave the way for the development of quantum nonreciprocal devices, with potential applications in quantum information processing and chiral networks.