arXiv subjects

Liqi Wang

Publications and source records attributed to Liqi Wang.

17 recordsLinked to original sources

arXiv2026

Hulls and sums of separable constacyclic codes over $\mathbb{F}_q \times (\mathbb{F}_q+v\mathbb{F}_q)$ and new quantum codes

We establish the generator polynomials of the Euclidean and Hermitian duals of separable constacyclic codes over $\mathcal{S} = \mathbb{F}_q \times (\mathbb{F}_q+v\mathbb{F}_q)$, with $q$ an odd prime power and $v^2=v$, and we derive the generator polynomials of their Gray images, respectively. The generator polynomials of the Euclidean hulls and Hermitian hulls of separable constacyclic codes over $\mathcal{S}$ and their Gray images are presented, respectively. Furthermore, we provide the generator polynomials of the Euclidean sums and Hermitian sums of separable constacyclic codes and their Gray images, respectively. Finally, we propose two methods to yield quantum error-correcting codes (QECCs) from the hulls and sums of separable constacyclic codes over $\mathcal{S}$, and generate new QECCs that outperform the existing ones in terms of parameters.

cs.IT↗

arXiv2026

A Posterior MWPM Decoding Boosts the XYZ Planar Code

The minimum-weight perfect matching (MWPM) decoder is a standard decoding strategy for surface codes, but its performance degrades considerably under biased noise. In this paper, a modified surface code, termed the XYZ planar code, is introduced, and the MWPM decoder is extended to posterior MWPM (pMWPM) with almost no increase in decoding complexity. The XYZ planar code exhibits higher and more stable thresholds than the planar code under almost all bias conditions, while also achieving significantly lower logical error rates. Specifically, in the infinite-bias case, the threshold of the XYZ planar code is improved by about $36\%$ compared to that of the surface code, and it maintains comparable or higher thresholds under other biases -- for example, the threshold reaches approximately $15.5\%$ at bias $η= 1$ and $14.2\%$ at $η= 100$. Furthermore, pMWPM can be adapted to a wide range of modified surface codes, and the results presented in this work also indicate its excellent potential in other scenarios, such as configurations in which $Y$ operators involve a larger number of data qubits.

cs.IT↗

arXiv2026

Design principles for amorphous solid-state electrolytes

Amorphous solid-state electrolytes (SSEs) offer unique advantages for next-generation batteries, but their rational design is hindered by an unclear structure-property relationship. This study establishes universal design principles through atomistic simulations of 32 amorphous Li-M-X systems (M = B, Al, Si, P; X = F, Cl, Br, I, O, S, Se, N). We identify four structure types governed by a rule that saturated M-X groups with more negative charges preferentially form M-X-M chains, identify paddle-wheel and cooperative migration as two favorable transport mechanisms that are significantly enhanced in amorphous structures. We also pinpoint Oxides and fluorides as optimal for electrochemical and hydrolytic stability, and reveal bulk modulus as a simple predictor for $Li^+$ mobility. These insights are integrated into a practical design diagram, providing a novel and valuable framework for advancing high-performance amorphous SSEs.

cond-mat.mtrl-sci↗

arXiv2025

Several new classes of MDS symbol-pair codes derived from matrix-product codes

In order to correct the pair-errors generated during the transmission of modern high-density data storage that the outputs of the channels consist of overlapping pairs of symbols, a new coding scheme named symbol-pair code is proposed. The error-correcting capability of the symbol-pair code is determined by its minimum symbol-pair distance. For such codes, the larger the minimum symbol-pair distance, the better. It is a challenging task to construct symbol-pair codes with optimal parameters, especially, maximum-distance-separable (MDS) symbol-pair codes. In this paper, the permutation equivalence codes of matrix-product codes with underlying matrices of orders $3$ and $4$ are used to extend the minimum symbol-pair distance, four new classes of MDS symbol-pair codes and a new class of AMDS symbol-pair codes are derived.

cs.IT↗

arXiv2025

EDIS: A Simulation Software for Dynamic Ion Intercalation/Deintercalation Processes in Electrode Materials

As the core determinant of lithium-ion battery performance, electrode materials play a crucial role in defining the battery's capacity, cycling stability, and durability. During charging and discharging, electrode materials undergo complex ion intercalation and deintercalation processes, accompanied by defect formation and structural evolution. However, the microscopic mechanisms underlying processes such as cation disordering, lattice oxygen loss, and stage structure formation phenomena are still not fully understood. To address these challenges, we have developed the Electrode Dynamic Ion Intercalation/Deintercalation Simulator (EDIS), a software platform designed to simulate the dynamic processes of ion intercalation and deintercalation in electrode materials. Leveraging high-precision machine learning potentials, EDIS can efficiently model structural evolution and lithium-ion diffusion behavior under various states of charge and discharge, achieving accuracy approaching that of quantum mechanical methods in relevant chemical spaces. The software supports quantitative analysis of how variations in lithium-ion concentration and distribution affect lithium-ion transport properties, enables evaluation of the impact of structural defects, and allows for tracking of both structural evolution and transport characteristics during continuous cycling. EDIS is versatile and can be extended to sodium-ion batteries and related systems. By enabling in-depth analysis of these microscopic processes, EDIS provides a robust theoretical tool for mechanistic studies and the rational design of high-performance electrode materials for next-generation lithium-ion batteries.

cond-mat.mtrl-sci↗

arXiv2025

Revealing the Staging Structural Evolution and Li (De)Intercalation Kinetics in Graphite Anodes via Machine Learning Potential

Revealing the dynamic structural evolution and lithium transport properties during the charge/discharge processes is crucial for optimizing graphite anodes in lithium-ion batteries, enabling high stability and fast-charging performance. However, the dynamic coupling mechanisms among carbon layer kinetics, lithium (de)intercalation/diffusion, and defects regulation remain insufficiently understood. In this study, we developed a universal automated workflow based on machine learning potentials to simulate the dynamic lithium (de)intercalation process. With this approach, the staging structural evolution of lithium-graphite intercalation compounds and their lithium transport behavior were resolved through molecular dynamics simulations. By introducing stacking faults into the graphite structure, we successfully simulated stage transitions driven by carbon layer sliding and reorganization, accompanied by stress release and structural stabilization. The dynamics of carbon layers regulate the lithium (de)intercalation positional selectivity, producing intermediate states with varying lithium concentrations and distributions during cycling. This facilitates the formation and transformation of stage structures while mitigating residual stress accumulation. A fundamental kinetic asymmetry arises between lithium intercalation and deintercalation, driven by the continuous and heterogeneous lithium transport and carbon layer sliding during charge/discharge processes. The carbon defects regulate lithium transport, in which the atomic-scale defects confine intralayer lithium transport and carbon sliding while enabling interlayer transport via dynamic lithium trapping/release mechanisms. Accordingly, for the future design, it is critical to construct structural units with controllable carbon layer sliding/reorganization, and tunable defects to enhance lithium-ion transport.

cond-mat.mtrl-sci↗

arXiv2025

High-Entropy Solid Electrolytes Discovery: A Dual-Stage Machine Learning Framework Bridging Atomic Configurations and Ionic Transport Properties

The rapid development of computational materials science powered by machine learning (ML) is gradually leading to solutions to several previously intractable scientific problems. One of the most prominent is machine learning interatomic potentials (MLIPs), which expedites the study of dynamical methods for large-scale systems. However, a promising field, high-entropy (HE) solid-state electrolytes (SEs) remain constrained by trial-and-error paradigms, lacking systematic computational strategies to address their huge and high-dimensional composition space. In this work, we establish a dual-stage ML framework that combines fine-tuned MLIPs with interpretable feature-property mapping to accelerate the high-entropy SEs discovery. Using Li$_3$Zr$_2$Si$_2$PO$_{12}$ (LZSP) as a prototype, the fine-tuned CHGNet-based relaxation provides atomic structure for each configuration, the structure features - mean squared displacement (SF-MSD) model predicts the ionic transport properties and identifies critical descriptors. The theoretical studies indicate that the framework can satisfy the multiple requirements including computational efficiency, generalization reliability and prediction accuracy. One of the most promising element combinations in the quinary HE-LZSP space containing 4575 compositions is identified with a high ionic conductivity of 4.53 mS/cm as an application example. The framework contains generalizability and extensibility to other SE families.

cond-mat.mtrl-sci↗

arXiv2024

Li$_{14}$Mn$_{2}$S$_{9}$ and Li$_{10}$Si$_{2}$S$_{9}$ as a pair of all-electrochem-active electrode and solid-state electrolyte with chemical compatibility and low interface resistance

In solid-state batteries (SSBs), improving the physical contact at the electrode-electrolyte interface is essential for achieving better performance and durability. On the one hand, it is necessary to look for solid-state electrolytes (SSEs) with high ionic conductivity and no reaction with the electrode, on the other hand, to design the all-electrochem-active (AEA) electrodes that contain no SSEs and other non-active substances. In this work, we proposed a pair of AEA-electrode and SSE with the same structural framework and excellent interface compatibility, Li$_{14}$Mn$_{2}$S$_{9}$ and Li$_{10}$Si$_{2}$S$_{9}$, and confirmed the feasibility by ab-initio molecular dynamics (AIMD) simulations and machine learning interatomic potential based molecular dynamics (MLIP-based MD) simulations, providing a new approach to promote interfacial stability in SSBs.

cond-mat.mtrl-sci↗

arXiv2024

A family of air-stable chalcogenide solid electrolytes in Li$_2$BMQ$_4$ (B = Ca, Sr and Ba; M = Si, Ge and Sn; Q = O, S and Se) systems

Combining high-throughput first-principles calculations and experimental measurements, we have identified a novel family of fast lithium-ion chalcogenide conductors in Li$_2$BMQ$_4$ (2114, B = Ca, Sr and Ba; M = Si, Ge and Sn; Q = O, S and Se) systems. Our calculations demonstrate that most of the thermodynamically and kinetically stable sulfides and selenides in this new system exhibit ultralow Li$^+$ ion migration activation energy (0.16 eV ~ 0.56 eV) and considerable bandgaps varying between ~ 2 eV and 3.5 eV. We have successfully synthesized Li$_2$BaSnS$_4$ and Li$_2$SrSiS$_4$, and they exhibit excellent moisture stability through H$_2$S gas measurements. Electrochemical impedance measurements indicate 2114 systems show the typical features of solid ionic conductors, with a room-temperature Li$^+$ conductivity close to 5$\times$10$^{-4}$ mS/cm aligning with our molecular dynamics simulations. Furthermore, we have theoretically investigated the substitution of Cl$^-$ at S$^{2-}$ site. The doped compounds display significantly higher conductivity, with an increase of about three orders of magnitude (up to a maximum of 0.72 mS/cm) compared to the undoped compounds. These findings offer valuable insights for the further exploration of potential chalcogenide solid electrolyte materials with robust air stability and enhanced ionic conductivity for practical applications in lithium-ion batteries.

cond-mat.mtrl-sci↗

arXiv2024

Constructions of entanglement-assisted quantum MDS codes from generalized Reed-Solomon codes

By generalizing the stabilizer quantum error-correcting codes, entanglement-assisted quantum error-correcting (EAQEC) codes were introduced, which could be derived from any classical linear codes via the relaxation of self-orthogonality conditions with the aid of pre-shared entanglement between the sender and the receiver. In this paper, three classes of entanglement-assisted quantum error-correcting maximum-distance-separable (EAQMDS) codes are constructed through generalized Reed-Solomon codes. Under our constructions, the minimum distances of our EAQMDS codes are much larger than those of the known EAQMDS codes of the same lengths that consume the same number of ebits. Furthermore, some of the lengths of the EAQMDS codes are not divisors of $q^2-1$, which are completely new and unlike all those known lengths existed before.

cs.IT↗

arXiv2023

R-Block: Regularized Block of Dropout for convolutional networks

Dropout as a regularization technique is widely used in fully connected layers while is less effective in convolutional layers. Therefore more structured forms of dropout have been proposed to regularize convolutional networks. The disadvantage of these methods is that the randomness introduced causes inconsistency between training and inference. In this paper, we apply a mutual learning training strategy for convolutional layer regularization, namely R-Block, which forces two outputs of the generated difference maximizing sub models to be consistent with each other. Concretely, R-Block minimizes the losses between the output distributions of two sub models with different drop regions for each sample in the training dataset. We design two approaches to construct such sub models. Our experiments demonstrate that R-Block achieves better performance than other existing structured dropout variants. We also demonstrate that our approaches to construct sub models outperforms others.

cs.CV↗

arXiv2020

On the constructions of $n$-cycle permutations

Any permutation polynomial is an $ n $-cycle permutation. When $n$ is a specific small positive integer, one can obtain efficient permutations, such as involutions, triple-cycle permutations and quadruple-cycle permutations. These permutations have important applications in cryptography and coding theory. Inspired by the AGW Criterion, we propose criteria for $ n $-cycle permutations, which mainly are of the form $ x^rh(x^s) $. We then propose unified constructing methods including recursive ways and a cyclotomic way for $ n $-cycle permutations of such form. We demonstrate our approaches by constructing three classes of explicit triple-cycle permutations with high index and two classes of $ n $-cycle permutations with low index.

cs.IT↗

arXiv2018

One-Lee weight and two-Lee weight $\mathbb{Z}_2\mathbb{Z}_2[u]$-additive codes

In this paper, we study one-Lee weight and two-Lee weight codes over $\mathbb{Z}_{2}\mathbb{Z}_{2}[u]$, where $u^{2}=0$. Some properties of one-Lee weight $\mathbb{Z}_{2}\mathbb{Z}_{2}[u]$-additive codes are given, and a complete classification of one-Lee weight $\mathbb{Z}_2\mathbb{Z}_2[u]$-additive formally self-dual codes is obtained. The structure of two-Lee weight projective $\mathbb{Z}_2\mathbb{Z}_2[u]$ codes is determined. Some optimal binary linear codes are obtained directly from one-Lee weight and two-Lee weight $\mathbb{Z}_{2}\mathbb{Z}_{2}[u]$-additive codes via the extended Gray map.

math.RA↗

arXiv2017

A note on complete classification of $(δ+αu^2)$-constacyclic codes of length $p^k$ over $\F_{p^m}+u\F_{p^m}+u^2\F_{p^m}$

For units $δ$ and $α$ in $\F_{p^m}$, the structure of $(δ+αu^2)$-constacyclic codes of length $p^k$ over $\mathbb{F}_{p^m}+u\mathbb{F}_{p^m}+u^2\mathbb{F}_{p^m}$ is studied and self-dual $(δ+αu^2)$-constacyclic codes are analyzed.

cs.IT↗

arXiv2016

The symbol-pair distance distribution of repeated-root cyclic codes over $\mathbb{F}_{p^m}$

Symbol-pair codes are proposed to protect against pair errors in symbol-pair read channels. One of the most important task in symbol-pair coding theory is to determine the minimum pair-distance of symbol-pair codes. In this paper, we investigate the symbol-pair distances of cyclic codes of length $p^e$ over $\mathbb{F}_{p^m}$. The exact symbol-pair distances of all cyclic codes of such length are determined.

cs.IT↗

arXiv2014

New quantum MDS codes derived from constacyclic codes

Quantum maximal-distance-separable (MDS) codes form an important class of quantum codes. It is very hard to construct quantum MDS codes with relatively large minimum distance. In this paper, based on classical constacyclic codes, we construct two classes of quantum MDS codes with parameters $$[[λ(q-1),λ(q-1)-2d+2,d]]_q$$ where $2\leq d\leq (q+1)/2+λ-1$, and $q+1=λr$ with $r$ even, and $$[[λ(q-1),λ(q-1)-2d+2,d]]_q$$ where $2\leq d\leq (q+1)/2+λ/2-1$, and $q+1=λr$ with $r$ odd. The quantum MDS codes exhibited here have parameters better than the ones available in the literature.

cs.IT↗

arXiv2014

On the Construction of Optimal Asymmetric Quantum Codes

Constacyclic codes are important classes of linear codes that have been applied to the construction of quantum codes. Six new families of asymmetric quantum codes derived from constacyclic codes are constructed in this paper. Moreover, the constructed asymmetric quantum codes are optimal and different from the codes available in the literature.

cs.IT↗