arXiv subjects

Chengliang Lin

Publications and source records attributed to Chengliang Lin.

9 recordsLinked to original sources

arXiv2026

The virial expansion of the Hydrogen equation of state in comparison to PIMC simulations: the quasiparticle concept, IPD, and ionization degree

The properties of plasmas in the low-density limit are described by virial expansions. Analytical expressions are known for the lowest virial coefficients from Green's function approaches.Recently, accurate path-integral Monte Carlo simulations were performed for the hydrogen plasma at low densities by Filinov and Bonitz [Phys. Rev. E 108 (2023)055212], which made a comparison of the virial expansions and the derivation of interpolation formulas possible. The exact expression for the second virial coefficient is used to test the accuracy of the PIMC simulations and the range of application of the virial expansions.To describe plasmas in a wider range of density and temperature, the concept of quasiparticles is considered. Medium modifications of free and bound states are obtained from the spectral function. Mean-field effects are presented, such as exchange terms, Pauli blocking and screening. The density expansions of the quasiparticle shifts is considered. The combination of PIMC simulations with benchmarks from exact virial expansion results allows us to obtain precise results for the EoS in the low-density range. At low densities, the results are compared with the Saha equation to introduce the medium-dependent ionization potential. The relation to the Beth-Uhlenbeck formula and concepts such as the Mott effect, ionization potential depression (IPD), and ionization degree are discussed. The limits of current PIMC results for hydrogen plasmas are shown. Further improvements of the PIMC simulations are required to compare with analytical benchmarks.

physics.plasm-ph↗

arXiv2026

Dielectric response and structural properties of finite-temperature electron liquids

The dielectric response and structural properties of finite-temperature electron liquids are central to accurately describing the physical behavior of electronic systems. This study presents a robust analytical model for the static structure factor of the uniform electron gas, combining physically motivated form for the static structure factor with constraints derived from high-accuracy path integral Monte Carlo simulations. The model accurately reproduces key features of the static structure factor across a broad range of temperatures and densities. Using this static structure factor, the density response function is directly evaluated, enabling a self-consistent definition of the static local field correction. As practical applications, the model is employed to investigate the low-velocity stopping power and the electron-ion friction coefficient. Results derived for the friction coefficient show good agreement with simulation data at moderate coupling and degeneracy. The proposed approach provides a computationally efficient and reliable method for characterizing the static response properties of correlated electron systems, facilitating improved simulations of energy deposition and ionic transport in warm dense matter and other strongly coupled quantum plasmas.

physics.plasm-ph↗

arXiv2025

On-device Semantic Selection Made Low Latency and Memory Efficient with Monolithic Forwarding

Semantic top-K selection with cross-encoder rerankers underpins on-device AI services, such as retrieval-augmented generation, agent memory, and personalized recommendation. However, its latency and memory demands dominate end-to-end budgets on edge hardware. Revisiting the objective of top-K selection, we reveal that only relative rankings matter, not exact per-candidate scores. We further observe sequence-level sparsity: relative rankings progressively stabilize in intermediate layers, enabling early pruning prior to completing full inference. Building on this insight, we propose monolithic forwarding and develop a training-free inference system, PRISM. By maintaining a global view of all candidates, it reduces latency through progressive cluster pruning. It also bounds peak memory usage by strategically overlapping I/O with computation via overlapped layer streaming and chunked execution. We evaluate PRISM against state-of-the-art baselines on rerankers from 0.6 B to 8 B parameters across Apple M2 and RTX 5070. PRISM consistently reduces latency by up to 89.2% and peak memory by up to 91.3% in microbenchmarks, without compromising precision. Across three real-world on-device AI applications, PRISM lowers latency by 11.6%-51.0% and peak memory by 18.6%-77.8%, demonstrating substantial improvements in efficiency and deployability.

cs.LG↗

arXiv2025

Benchmarking Generalizable Bimanual Manipulation: RoboTwin Dual-Arm Collaboration Challenge at CVPR 2025 MEIS Workshop

Embodied Artificial Intelligence (Embodied AI) is an emerging frontier in robotics, driven by the need for autonomous systems that can perceive, reason, and act in complex physical environments. While single-arm systems have shown strong task performance, collaborative dual-arm systems are essential for handling more intricate tasks involving rigid, deformable, and tactile-sensitive objects. To advance this goal, we launched the RoboTwin Dual-Arm Collaboration Challenge at the 2nd MEIS Workshop, CVPR 2025. Built on the RoboTwin Simulation platform (1.0 and 2.0) and the AgileX COBOT-Magic Robot platform, the competition consisted of three stages: Simulation Round 1, Simulation Round 2, and a final Real-World Round. Participants totally tackled 17 dual-arm manipulation tasks, covering rigid, deformable, and tactile-based scenarios. The challenge attracted 64 global teams and over 400 participants, producing top-performing solutions like SEM and AnchorDP3 and generating valuable insights into generalizable bimanual policy learning. This report outlines the competition setup, task design, evaluation methodology, key findings and future direction, aiming to support future research on robust and generalizable bimanual manipulation policies. The Challenge Webpage is available at https://robotwin-benchmark.github.io/cvpr-2025-challenge/.

cs.RO↗

arXiv2019

Ionization potential depression and ionization balance in dense plasmas

Theoretical modelling of ionization potential depression and the related ionization equilibrium in dense plasmas, in particular in warm/hot dense matter, represents a significant challenge due to ionic coupling and electronic degeneracy effects. We present a quantum statistical model based on dynamical structure factors for the ionization potential depression, where quantum exchange and dynamical correlation effects in plasma environments are consistently and systematically taken into account in terms of the concept of self-energy. Under the condition of local thermodynamic equilibrium, the charge state distribution (or ionic fraction) characterized by the ionization balance is obtained by solving the coupled Saha equations. Calculations for the ionization potential depression of different chemical elements are performed with the electronic and ionic structure factors. The ionic structure factors are determined by solving the Ornstein-Zernike equation in combination with the hypernetted-chain equation. As a further application of our approach, we present results for the charge state distribution of aluminium plasmas at several temperatures and densities.

physics.plasm-ph↗

arXiv2018

Ionization potential depression and Pauli blocking in degenerate plasmas at extreme densities

New facilities explore warm dense matter (WDM) at extreme conditions where the densities are very high (e.g., carbon up to density of 50 g cm$^{-3}$) so that electrons are degenerate even at 100 eV temperature. Whereas in the non-degenerate region correlation effects such as Debye screening and its improvements are relevant for the ionization potential depression (IPD), new effects have to be considered in degenerate plasmas. In addition to the Fock shift of the self-energies, the bound-state Pauli blocking becomes important with increasing density. Taking these degeneracy effects into account leads to a reduction of the ionization potential and to a higher degree of ionization. Standard approaches to IPD such as Stewart-Pyatt and widely used opacity tables (e.g., OPAL) do not contain Pauli blocking effects for bound states so that they fail to explain experiments with WDM in the high density region. As example, results for the ionization degree of carbon plasmas are presented.

physics.plasm-ph↗

arXiv2017

Ionization potential depression and optical spectra in a Debye plasma model

We show how optical spectra in dense plasmas are determined by the shift of energy levels as well as the broadening owing to collisions with the plasma particles. In lowest approximation, the interaction with the plasma particles is described by the RPA dielectric function, leading to the Debye shift of the continuum edge. The bound states remain nearly un-shifted, their broadening is calculated in Born approximation. The role of ionization potential depression as well as the Inglis-Teller effect are shown. The model calculations have to be improved going beyond the lowest (RPA) approximation when applying to WDM spectra.

physics.plasm-ph↗

arXiv2017

Ionization potential depression and dynamical structure factor in dense plasmas

The properties of a bound electron system immersed in a plasma environment are strongly modified by the surrounding plasma. The modification of a basic quantity, the ionization energy, is described by the electronic self-energy and by dynamical screening within the framework of the quantum statistical theory. Introducing the ionic dynamical structure factor as the indicator for the ionic micro-field, we demonstrate that ionic correlations and fluctuations play a critical role in determining the ionization potential depression. This is in particular true for mixtures of different ions with large mass and charge asymmetry. The ionization potential depression is calculated for dense aluminum plasmas as well as for a CH plasma and compared to the experimental data and more phenomenological approaches used so far.

physics.plasm-ph↗

arXiv2016

Transition Rates for a Rydberg Atom Surrounded by a Plasma

We derive a quantum master equation for an atom coupled to a heat bath represented by a charged particle many-body environment. In Born-Markov approximation, the influence of the plasma environment on the reduced system is described by the dynamical structure factor. Expressions for the profiles of spectral lines are obtained. Wave packets are introduced as robust states allowing for a quasi-classical description of Rydberg electrons. Transition rates for highly excited Rydberg levels are investigated. A circular-orbit wave packet approach has been applied, in order to describe the localization of electrons within Rydberg states. The calculated transition rates are in a good agreement with experimental data.

physics.atom-ph↗