arXiv subjects

Hanbo Yang

Publications and source records attributed to Hanbo Yang.

3 recordsLinked to original sources

arXiv2026

Low-Loss Optical Nanofibers with Submicron Waist Diameters and Millimeter-Scale Waist Lengths

Optical nanofibers with subwavelength diameters generate strong evanescent fields, enabling efficient light-matter interactions for optical sensing, spectroscopy, and cold-atom experiments. We report a heat-and-pull system for fabricating low-loss optical nanofibers with controllable waist dimensions and investigate the fabrication limits for achieving small waist diameters and long waist lengths. We study factors that influence fabrication performance, including flame geometry, nanofiber dimensions, and surface contamination. Using a multi-hole torch tip that provides a relatively large and uniform heating region, we achieve reproducible fabrication with optical transmission above $99.9\%$ for waist diameters as small as 200 nm for a 1-mm waist length and 250 nm for a 50-mm waist length. We also develop a preparation procedure for fiber splicing and cleaning to minimize transmission loss caused by surface contamination. In addition, we measure long-term transmission degradation due to dust accumulation in a typical laboratory environment and find that nanofibers fabricated in an enclosed setup maintain transmission above $85\%$ for more than 1 hour for nanofibers with a 300-nm waist diameter and waist lengths ranging from 1 to 30 mm. Our work provides practical guidelines for constructing nanofiber fabrication platforms and producing low-loss nanofibers for optics and atomic physics applications.

physics.optics↗

arXiv2025

Single-Beam Magneto-Optical Trap in Back-to-Back Pyramidal and Conical Mirrors

A three-dimensional magneto-optical trap (MOT), as an efficient method of producing cold atoms from room-temperature atomic vapor, has been widely used to develop atomic sensors. Various compact MOTs using a single laser beam have been reported, simplifying apparatuses and leading to miniaturized devices. Here, we propose single-beam MOTs based on back-to-back pyramidal and conical mirrors. In such back-to-back mirrors, a MOT trapping volume is formed by an incident laser beam, a retroreflected beam, and multiple reflections from the mirror surfaces. We present the design of back-to-back mirrors and a series of compact MOT configurations, with the potential of increasing access to the MOT and simultaneously creating multiple MOTs. We demonstrate a MOT in a back-to-back conical mirror, loading 10 million rubidium-87 atoms from background vapor and cooling the atoms to 7 {\mu}K using polarization gradients. Single-beam MOTs based on back-to-back mirrors will contribute to building compact and scalable cold-atom-based sensors.

physics.atom-ph↗

arXiv2024

Transfer Learning for High-dimensional Quantile Regression with Distribution Shift

Information from related source studies can often enhance the findings of a target study. However, the distribution shift between target and source studies can severely impact the efficiency of knowledge transfer. In the high-dimensional regression setting, existing transfer approaches mainly focus on the parameter shift. In this paper, we focus on the high-dimensional quantile regression with knowledge transfer under three types of distribution shift: parameter shift, covariate shift, and residual shift. We propose a novel transferable set and a new transfer framework to address the above three discrepancies. Non-asymptotic estimation error bounds and source detection consistency are established to validate the availability and superiority of our method in the presence of distribution shift. Additionally, an orthogonal debiased approach is proposed for statistical inference with knowledge transfer, leading to sharper asymptotic results. Extensive simulation results as well as real data applications further demonstrate the effectiveness of our proposed procedure.

stat.ME↗