arXiv subjects

Yangguang Zhong

Publications and source records attributed to Yangguang Zhong.

3 recordsLinked to original sources

arXiv2026

Tensor-Engineered Van der Waals NbOCl2 Resonant Metasurface for Polarization-entangled Bell State Generation

Polarization-entangled photon pairs are essential resources for quantum information technologies, yet realizing compact sources with intrinsically controllable entanglement remains challenging. Van der Waals (vdW) nonlinear materials such as NbOCl2 provide atomically thin platforms for quantum light generation, yet their native crystalline anisotropies as natural materials impose limitations on accessible quantum states. Here, we develop a resonant vdW nonlinear metasurface based on NbOCl2 that exploits its intrinsic optical anisotropy to engineer polarization-dependent nonlinear responses. The anisotropic optical dispersion enables selective manipulation of resonant modes, resulting in a three-order-of-magnitude enhancement of the nonlinear response along the c axis. By further tailoring these resonant modes, we redistribute the effective second-order nonlinear susceptibility tensor between orthogonal polarization channels, balancing the spontaneous parametric down-conversion pathways along the b and c axes. This enables polarization-entangled photon generation with a measured fidelity of up to 92%. Our work establishes metasurface-enabled nonlinear optical engineering as a strategy for enhancing and controlling quantum light generation in vdW materials, providing a pathway toward scalable quantum photonic platforms.

physics.optics↗

arXiv2025

All-optical and ultrafast control of high-order exciton-polariton orbital modes

Exciton-polaritons flows within closed quantum circuits can spontaneously form phase-locked modes that carry orbital angular momentum (OAM). With its infinite set of angular momentum quantum numbers, high-order OAM represents a transformative solution to the bandwidth bottleneck in multiplexed optical communication. However, its practical application is hindered by the limited choice of materials which in general requires cryogenic temperatures and the reliance on mechanical switching. In this work, we achieve stable and high-order (up to order of 33) OAM modes by constructing a closed quantum circuit using the halide perovskite microcavities at room temperature. By controlling the spatial and temporal symmetry of the closed quantum circuits using another laser pulse, we achieve significant tuning OAM of EP flows from 8 to 12. Our work demonstrate all-optical and ultrafast control of high-order OAM using exciton-polariton condensates in perovskite microcavities that would have important applications in high-throughput optical communications.

physics.optics↗

arXiv2024

Ultrafast carriers' separation imaging in WS2-WSe2 in plane heterojunction by transient reflectivity microscopy

Carrier transport in nanodevices plays a crucial role in determining their functionality. In the post-Moore era, the behavior of carriers near surface or interface domains the function of the whole devices. However, the femtosecond dynamics and nanometer-scale movement of carriers pose challenges for imaging their behavior. Techniques with high spatial-temporal resolution become imperative for tracking their intricate dynamics. In this study, we employed transient reflectivity microscopy to directly visualize the charge separation in the atomic interface of WS2-WSe2 in-plane heterojunctions. The carriers' drifting behavior was carefully tracked, enabling the extraction of drift velocities of 30 nm/ps and 10.6 nm/ps for electrons and holes. Additionally, the width of the depletion layer was determined to be 300 nm based on the carriers' moving trajectory. This work provides essential parameters for the potential effective utilization of these covalent in-plane heterojunctions,and demonstrates the success of transient optical imaging in unraveling the electrical behavior of nano devices, paving the way for a new avenue of electro-optical analysis.

cond-mat.mes-hall↗