Science China Physics, Mechanics & Astronomy最新文献

In spinless systems, growing attention has recently been attracted to synthetic gauge fields, which redefine the fundamental crystal symmetries by utilizing the projective algebraic relation. Hitherto, synthetic gauge fields have been commonly investigated in single orbital systems, and explorations on hybrid orbitals remain elusive in acoustics. Here, we report the experimental observation of hybrid topological phases induced by hybrid synthetic gauge flux, which is formed by the interaction between p and d orbitals embedded in acoustic cavities. By breaking the translation symmetries of L_x and/or L_y, we unambiguously demonstrate the first-order Möbius edge states and higher-order corner states. This work establishes a platform for seeking exotic topological phases induced by hybrid-orbitals interactions and initializing the framework of hybrid-orbitals-related topological physics. Potential applications can be anticipated in scenarios such as high-quality sensing and robust wave trapping due to the stepwise energy distribution of the hybrid topological phase.

The interplay between novel topological states and superconductivity has garnered substantial interest due to its potential for topological quantum computing. The Josephson effect serves as a useful probe for edge superconductivity in these hybrid topological materials. In Josephson junctions based on topological materials, supercurrents exhibit unique quantum interference patterns, including the conventional Fraunhofer oscillations, the Φ₀-periodic oscillation, and the 2Φ₀-periodic oscillation in response to the external magnetic field (Φ₀ = h/2e is the flux quantum, h the Planck constant, and e the electron charge). These interference patterns stem from varied Andreev reflection mechanisms and the associated current density profiles. This review seeks to comprehensively examine the theoretical and experimental advancements in understanding the quantum interference patterns of edge supercurrents in Josephson junctions based on quantum spin Hall, quantum Hall, and quantum anomalous Hall systems.

Bound states in the continuum (BICs) are perfectly localized resonances despite embedding in the continuum spectrum. However, an isolated BIC is very sensitive to the structure perturbation. Here, we report merging acoustic BICs in a single open resonator, robust against the structure perturbation. We find that both symmetry-protected BIC and Friedrich-Wintgen BIC are sustained in a single coupled waveguide-resonator system. By varying the height and length of the resonator, these two BICs move toward each other and merge into a single one at a critical dimension. Compared to an individual BIC, the merged BIC is robust against fabrication error because its Q-factor is proportional to ΔL⁻⁴, where ΔL embodies the structure perturbation. The essence of this extraordinary phenomenon is perfectly explained by the two- and three-level approximations of the effective non-Hermitian Hamiltonian. Finally, we present direct experimental demonstrations of the moving and merging of BICs in a coupled 3D waveguide-resonator, which are evidenced by the vanishing of the linewidth of Fano resonance in the transmission spectra. Our results may find exciting applications in designing high-quality acoustic sources, sensors and filters.

With the development of quantum computing technology, quantum public-key cryptography is gradually becoming an alternative to the existing classical public-key cryptography. This paper designs a quantum trapdoor one-way function via EPR pairs and quantum measurements. Based on this, a new quantum public-key cryptosystem is presented, which offers forward security, and can resist the chosen-plaintext attack and chosen-ciphertext attack. Compared with the existing quantum public-key cryptos, eavesdropping can be automatically detected in this new quantum public-key cryptosystem under a necessary condition, which is also detailed in the paper.

The standard model of modern cosmology might be cracked by the recent persistent hot debate on the Hubble-constant (H₀) tension, which manifests itself as the sound-horizon (r_s) tension or absolute-magnitude (M_B) tension if deeming the origin of the Hubble tension from modifying the early or late Universe, respectively. In this study, we achieve a fully model-independent constraint (fitting a model-independent global parameterization to a model-independent inverse distant ladder with a model-independent high-redshift calibration) on late-time models with strong evidence against homogeneous new physics over the Λ-cold-dark-matter (ΛCDM) model. Further using this model-independent constraint to calibrate sufficiently local supernovae with corresponding late-time models extrapolated below the homogeneity scale, we find surprisingly that, although both H₀ tension and M_B tension are absent in our local Universe, a combination of H₀ and M_B as the intercept a_B of the magnitude-redshift relation exhibits 3 ∼ 7σ tension even for the ΛCDM model. This a_B tension seems to call for local-scale inhomogeneous new physics disguised as local observational systematics.

Particle accelerators play a critical role in modern scientific research. However, existing manual beam control methods heavily rely on experienced operators, leading to significant time consumption and potential challenges in managing next-generation accelerators characterized by higher beam current and stronger nonlinear properties. In this paper, we establish a dynamical foundation for designing the online adaptive controller of accelerators using machine learning. This provides a guarantee for dynamic controllability for a class of scientific instruments whose dynamics are described by spatial-temporal equations of motion but only part variables along the instruments under steady states are available. The necessity of using historical time series of beam diagnostic data is emphasised. Key strategies involve also employing a well-established virtual beamline of accelerators, by which various beam calibration scenarios that actual accelerators may encounter are produced. Then the reinforcement learning algorithm is adopted to train the controller with the interaction to the virtual beamline. Finally, the controller is seamlessly transitioned to real ion accelerators, enabling efficient online adaptive control and maintenance. Notably, the controller demonstrates significant robustness, effectively managing beams with diverse charge mass ratios without requiring retraining. Such a controller allows us to achieve the global control within the entire superconducting section of the China Accelerator Facility for Superheavy Elements.

Nonadiabatic holonomic quantum computers serve as the physical platform for nonadiabatic holonomic quantum computation. As quantum computation has entered the noisy intermediate-scale era, building accurate intermediate-scale nonadiabatic holonomic quantum computers is clearly necessary. Given that measurements are the sole means of extracting information, they play an indispensable role in nonadiabatic holonomic quantum computers. Accordingly, developing methods to reduce measurement errors in nonadiabatic holonomic quantum computers is of great importance. However, while much attention has been given to the research on nonadiabatic holonomic gates, the research on reducing measurement errors in nonadiabatic holonomic quantum computers is severely lacking. In this study, we propose a measurement error reduction method tailored for intermediate-scale nonadiabatic holonomic quantum computers. The reason we say this is because our method can not only reduce the measurement errors in the computer but also be useful in mitigating errors originating from nonadiabatic holonomic gates. Given these features, our method significantly advances the construction of accurate intermediate-scale nonadiabatic holonomic quantum computers.

Silk damping is well known in the study of cosmic microwave background (CMB) and accounts for suppression of the angular power spectrum of CMB on large angular multipoles. In this article, we study the effect of Silk damping on the scalar-induced gravitational waves (SIGWs). Resulting from the dissipation of cosmic fluid, the Silk damping notably suppresses the energy-density spectrum of SIGWs on scales comparable to a diffusion scale at the decoupling time of weakly-interacting particles. The effect offers a novel observable for probing the underlying particle interaction, especially for those mediated by heavy gauge bosons beyond the standard model of particles. We anticipate that pulsar timing arrays are sensitive to gauge bosons with mass ∼ 10³–10⁴ GeV, while space- and ground-based interferometers to those with mass ∼ 10⁷–10¹² GeV, leading to essential complements to on-going and future experiments of high-energy physics.

The multi-class classification of images is a pivotal challenge within the realm of image processing. As the volume of visual data continues to expand, there is a burgeoning interest in harnessing the unique capabilities of quantum computation to augment the efficiency of classification tasks. However, many existing methods for training quantum image multi-classifiers parallel classical machine learning techniques, where the requisite circuit measurements increase linearly with the volume of training data. This work introduces a novel approach for training a quantum image multi-classifier based on the quantum search algorithm. We have meticulously conducted rigorous experiments on a handwritten digit dataset, a classic benchmark in the field. The results have been meticulously compared with previous works, and the comparative analysis not only validates the efficiency of our proposed approach, requiring only O(N/b) measurements during training, but also highlights a significant quadratic speedup of the algorithm.

Diverse wrinkling patterns can occur on curved bilayer systems under differential growth or expansion. In such systems, stress anisotropy is frequently encountered, and the coupling effect of curvature and stress anisotropy on the pattern evolution remains largely unexplored. In this study, we investigate the evolution of wrinkling patterns on a cylinder core-shell system with stress anisotropy leveraging both theoretical analysis and finite element simulations. Critical buckling analysis has identified three distinct critical buckling modes regulated by the stress anisotropy, i.e., axial sinusoidal mode, checkerboard mode, and circumferential sinusoidal mode. Our finite element simulations, along with post-buckling analysis, reveal seven distinct evolutionary paths stemming from the three critical buckling modes. We present phase diagrams for both the critical buckling modes and their evolutionary paths, which are determined by dimensionless curvature and stress anisotropy. Our results not only expand the theoretical research on surface wrinkling of a core-shell soft cylinder but also introduce stress anisotropy as a significant parameter for regulating the wrinkling patterns and their evolutionary paths in curved bilayer systems. The revelation of a multitude of wrinkling patterns and their evolutionary pathways holds great potential for advancing applications that leverage tunable wrinkle surfaces.