arXiv subjects

Xinye Fan

Publications and source records attributed to Xinye Fan.

3 recordsLinked to original sources

arXiv2026

Quantum Many-Body Principles of Localized-State Ensemble Luminescence

Localized electron states induced by various disorders, including defects and impurities, usually exist in solids. Their electrical properties have been extensively investigated and well documented, while their optical properties such as localized-state ensemble (LSE) luminescence remain poorly understood. In particular, a microscopic quantum many-body (MB) theory has not yet been established for LSE luminescence so far. In this Letter, we attempt to fill this void via developing a quantum MB luminescence theory taking into account both electron-phonon (e-p) and electron-electron (e-e) interactions. Abnormal thermal behaviors such as redshift and subsequent blueshift of peak position, narrowing and succeeding broadening of linewidth, decline in intensity, and variation in lifetime can be quantitatively interpreted. Within the framework of the MB-LSE theory, moreover, Varshni's empirical formula for bandgap temperature dependence and Huang-Rhys factor for e-p coupling, and other key formulas are further derived and discussed.

quant-ph↗

arXiv2025

Quantum Optics Nature of the Elementary Excitations in Few-Layer WSe2 Semiconductors

A fully quantized description of a two-level system resonantly coupled with an electromagnetic field (light) is among the central topics of quantum electrodynamics, which is theorized by the quantum Rabi model. It is also a fundamental issue of light-matter interactions. The rapid development of two-dimensional (2D) transition-metal dichalcogenide (TMDC) atomically-thin semiconductors brings excellent great chance to test and demonstrate some basic predictions by quantum optics theory in textbook, i.e., by the quantum Rabi model. Such test and demonstration are of both scientific and technological significance because of the quick emergence of the second quantum revolution. In this Letter, we show a quantum optics demonstration of the variable-temperature optical responses of the elementary excitations in few-layer WSe2 flakes. It is unraveled that the variable-temperature reflectance and fluorescence patterns of the elementary excitations (i.e., the band-edge excitons) of monolayer, bilayer and hBN capped WSe2 match well with the predictions by the quantum Rabi model under the rotating wave approximation. Decoherence times, Rabi frequencies, and transition matrix elements of the elementary excitations in these few-layer WSe2 flakes are found to be all negatively correlated with temperature, and to show dependence on layer number and capping layer. These findings may provide a novel perspective for comprehending the fundamental quantum physical properties of two-dimensional materials.

physics.optics↗

arXiv2025

Temperature dependence of quasi-localized phonons-mediated non-Markovianity dynamics of SiV^- centers in diamond

Here we investigate the temperature-dependent non-Markovian dynamics of the SiV^- center in diamond, focusing on the roles of low- and high-frequency quasi-localized phonon modes. Low-frequency phonons exhibit stronger electron-phonon coupling, leading to long-lived dephasing rate, while high-frequency phonons induce rapid attenuation of oscillatory dephasing rate facilitating a persistent memory effect. The non-Markovianity measure N_C shows memory effects persisting at low temperatures but diminishing at high temperatures due to enhanced damping. The temperature dependence of N_C follows a monotonic decay, from which a transition temperature T_NM=110 K is determined. These results highlight the interplay between phonon activation and damping in shaping quantum coherence, offering insights for optimizing solid-state quantum systems.

physics.optics↗