arXiv subjects

Xiangrui Hou

Publications and source records attributed to Xiangrui Hou.

5 recordsLinked to original sources

arXiv2026

Nonlinear Photonic Tripartite Phase

Anderson localization is usually understood as a transition between extended and localized phases, with criticality confined to a single mobility edge. Recent advances predict that quasiperiodic systems can instead host a finite critical window bounded by mobility edges, in which localized, critical and extended states coexist. Yet both the experimental realization of this regime and whether interactions can provide controlled access to it remain unknown. Here, we realize such a tripartite phase in a nonlinear quasiperiodic photonic lattice and show that Kerr nonlinearity, acting as an effective interaction, enables state-selective access to the critical window. By tracking wavepacket dynamics, we distinguish localized, critical and extended transport regimes and uncover a state-selective response: rather than simply reinforcing localization through self-trapping, weak nonlinearity drives low-energy localized states into the critical window, whereas stronger nonlinearity restores localization. By contrast, critical, extended and high-energy localized states evolve monotonically towards self-trapped behaviour. Our results reveal a state-selective mechanism by which interactions provide controlled access to a pre-existing critical window in quasiperiodic systems.

cond-mat.mes-hall↗

arXiv2026

M$^2$E-UAV: A Benchmark and Analysis for Onboard Motion-on-Motion Event-Based Tiny UAV Detection

Tiny UAV detection from an onboard event camera is difficult when the observer and target move at the same time. In this motion-on-motion regime, ego-motion activates background edges across buildings, vegetation, and horizon structures, while the UAV may appear as a sparse event cluster. Unlike static- or ground-observer event-based UAV detection, onboard UAV-view detection breaks the clean-background assumption because sensor ego-motion can activate dense background events over the entire field of view. To explore this practical problem, we present M$^2$E-UAV, to the best of our knowledge, the first onboard UAV-view motion-on-motion event-based dataset and benchmark for tiny UAV detection, where both the sensing platform and the target UAV are moving. M$^2$E-UAV provides synchronized event streams and IMU measurements collected from an onboard sensing platform, together with event-level UAV foreground labels derived from temporally propagated 10 Hz bounding-box annotations. The processed benchmark contains 87,223 training samples and 21,395 validation samples across four scene families: sunny building-forest, sunny farm-village, sunset building-forest, and sunset farm-village. We define a train/validation split and an evaluation protocol for comparing representative existing baselines across event-frame, voxel-grid, and point-set representations, with optional IMU input. The benchmark results show that existing baselines remain limited under sparse tiny-target evidence and dense ego-motion-induced background events. Code and benchmark files will be released at https://github.com/Wickyan/M2E-UAV.

cs.CV↗

arXiv2026

Massive coherent equipartition of light by the geometric phase of null space

Light source is a foundational to photonic science and technology. However, a significant challenge remains in generating and distributing coherent light from a single on-chip source with high phase stability across multiple channels. Integrated lasers typically operate independently, and conventional splitters (e.g., multi-mode interferometers) do not guarantee the phase coherence required for advanced applications. Here, we report a purely geometric scheme for achieving massive equipartition of coherent light on a photonic chip by leveraging the geometric phases of a null space spanned by degenerate states with zero eigenvalue. The evolution of the null space maps to real-space rotation described by the special orthogonal group SO(N), thus enabling precise and scalable control over light distribution by engineering the system parameters. We experimentally realize up to one-to-nine equipartition of light on a waveguide array fabricated on a glass-based photonic chip. The framework can be upscaled for one-to-N light distribution. This work establishes a versatile and scalable platform for integrated coherent light sources, paving the way for integrated photonic applications such as quantum photonics and optical computing.

physics.optics↗

arXiv2025

Quantum boomerang effect of light

The quantum boomerang effect is a counterintuitive phenomenon where a wave packet, despite having an initial momentum, returns to its starting position in a disordered medium. However, up to now, the experimental exploration of this effect remains largely unexplored. Here, we report the experimental observation of the quantum boomerang effect of light. Our experiment is based on a one-dimensional disordered photonic lattice, which is composed of on-chip optical waveguides with engineered on-site random potential. We first characterize this optical disordered system by demonstrating the static Anderson localization of light beams. Next, through launching a kinetic light beam into the system, we observe that the light beam first moves away from its starting point, arrives at a maximum value, reverses its direction, and returns to its original position over time, confirming the observation of the quantum boomerang effect of light. Surprisingly, we find that optical loss, usually considered to be detrimental to optical experiments, can enhance the quantum boomerang effect by accelerating the light back to its original position. Our work provides new insights into the light-matter interactions in disordered medium and opens an avenue for future study of this phenomenon in nonlinear and many-photon contexts.

physics.optics↗

arXiv2023

Photonic Floquet skin-topological effect

Non-Hermitian skin effect and photonic topological edge states are of great interest in non-Hermitian physics and optics. However, the interplay between them is largly unexplored. Here, we propose and demonstrate experimentally the non-Hermitian skin effect that constructed from the nonreciprocal flow of Floquet topological edge states, which can be dubbed 'Floquet skin-topological effect'. We first show the non-Hermitian skin effect can be induced by pure loss when the one-dimensional (1D) system is periodically driven. Next, based on a two-dimensional (2D) Floquet topological photonic lattice with structured loss, we investigate the interaction between the non-Hermiticity and the topological edge states. We observe that all the one-way edge states are imposed onto specific corners, featuring both the non-Hermitian skin effect and topological edge states. Furthermore, a topological switch for the skin-topological effect is presented by utilizing the gap-closing mechanism. Our experiment paves the way of realizing non-Hermitian topological effects in nonlinear and quantum regimes.

cond-mat.mes-hall↗