arXiv subjects

Yunlong Xue

Publications and source records attributed to Yunlong Xue.

4 recordsLinked to original sources

arXiv2026

Floquet-sideband-enhanced shortwave electrometry with Rydberg atoms

Rydberg atomic electric-field sensors, under the framework of optical excitation and readout, can overcome the size-to-wavelength constraint imposed by the Chu limit. However, their sensitivity for decametric-wavelength shortwave electric fields is substantially lower than that for microwave ones, stemming from the off-resonant nature of low-frequency signals with Rydberg transitions. Here, we demonstrate a high-sensitivity heterodyne shortwave sensor based on microwave-dressed Rydberg atoms, leveraging precisely modulated Floquet sidebands. Around local- and microwave-field-engineered Floquet sidebands, the steep response gradient, arising from the enhanced atom-shortwave interaction through additionally created coherent channels, induces pronounced amplification of the heterodyne intermediate-frequency signal. As a result, compared to the same atomic heterodyne setup without microwave modulation, such Floquet-sideband-enhanced shortwave measurement boosts the sensitivity by four orders of magnitude, yielding a sensitivity of -122.7 dBm/Hz for shortwave at 30 MHz. This work offers a potential route to high-sensitive portable shortwave receivers in radio astronomy, radar and long-distance communications.

physics.atom-ph↗

arXiv2026

HAFM: Hierarchical Autoregressive Foundation Model for Music Accompaniment Generation

Music accompaniment generation aims to automatically produce instrumental accompaniments that are rhythmically, harmonically, and timbrally coherent with a given vocal input, with broad applications in personalized music creation, arrangement assistance, and music education. Existing approaches, primarily operating in the symbolic domain or relying on single-stage audio generation frameworks, commonly suffer from insufficient high-level semantic structure modeling, limited acoustic detail reconstruction, and weak conditional controllability. To address these limitations, this paper proposes HAFM, a Hierarchical Autoregressive Foundation Model for vocal-conditioned music accompaniment generation. The model employs a dual-rate tokenization strategy in which $50$ Hz HuBERT semantic tokens capture high-level musical structure and $75$ Hz EnCodec acoustic tokens encode fine-grained acoustic content, enabling explicit disentanglement of semantic and acoustic representations. Building on this foundation, a three-stage cascaded generation framework is designed to progressively generate semantic tokens, coarse acoustic tokens, and fine acoustic tokens, refining the accompaniment from global structure to local detail. . Objective evaluation on the MUSDB18 dataset demonstrates that the full three-stage model achieves a Fr{\'e}chet Audio Distance (FAD) score of 1.71, representing an 18.6% relative improvement over the two-stage baseline (FAD = 2.10). Subjective listening tests show that the generated accompaniments achieve a 51.5% preference rate against ground-truth accompaniments in head-to-head comparisons, and substantially outperform the random baseline in terms of rhythmic alignment, harmonic compatibility, and overall musical coherence. The source code and demo are available at https://github.com/HackerHyper/HAFM.git.

cs.SD↗

arXiv2026

Enhanced Microwave Sensing with Dissipative Continuous Time Crystals

A dissipative time crystal is an emergent phase in driven-dissipative quantum many-body systems, characterized by sustained oscillations that break time-translation symmetry spontaneously. Here, we explore nonequilibrium phase transitions in a dissipative Rydberg system driven by a microwave (MW) field and demonstrate their critical sensitivity to high-precision MW sensing. Distinct dynamical regimes are identified, including monostable, bistable, and oscillatory phases under mean-field coupling. Unlike single-particle detection--where the beating signal decays linearly with MW field strength--the time crystalline phase exhibits high sensitivity to MW perturbations, with rapid, discontinuous frequency switching near the monostable-oscillatory boundary. The abrupt transition is rooted in spontaneous symmetry breaking in time and is fundamentally insensitive to the background noise. On this basis, a minimum detectable MW field strength on the order of 1nV/cm is achieved by leveraging this sensitivity. Our results establish a framework for controlling time crystalline phases with external fields and advance MW sensing through many-body effects.

cond-mat.quant-gas↗

arXiv2025

Non-reciprocal Synchronization in Thermal Rydberg Ensembles

Optical non-reciprocity is a fundamental phenomenon in photonics. It is crucial for developing devices that rely on directional signal control, such as optical isolators and circulators. However, most research in this field has focused on systems in equilibrium or steady states. In this work, we demonstrate a room-temperature Rydberg atomic platform where the unidirectional propagation of light acts as a switch to mediate time-crystalline-like collective oscillations through atomic synchronization. We find that thermal-motion-induced coupling asymmetry, enabled by counterpropagating probe and control fields, generates persistent oscillations; conversely, co-propagation quenches this effect. We identify, through both numerical and analytical approaches, the criteria for realizing optical non-reciprocity within a synchronization regime. These results provide key insights for chiral quantum optics and promote the on-chip integration of non-reciprocal devices in nonequilibrium many-body systems.

quant-ph↗