arXiv subjects

Jianxin Zhong

Publications and source records attributed to Jianxin Zhong.

At least 19 recordsLinked to original sources

arXiv2026

Non-Hermitian engineering of superfluidity in a Rashba spin-orbit-coupled Fermi gas

We investigate superfluid pairing in a two-dimensional Rashba spin-orbit-coupled Fermi gas subject to spin-selective one-body loss. Within the non-Hermitian mean-field framework, we self- consistently solve the gap and number equations and find that moderate dissipation can significantly enhance the pairing gap, resulting in a pronounced nonmonotonic dependence on the dissipation strength. Dissipation also provides an additional control parameter for driving the system across the BCS-BEC crossover. We further analyze the quasi-particle spectrum and identify two distinct superfluid regimes characterized by one and three exceptional rings, separated by an exceptional spectral transition. Interestingly, dissipation can enhance both pairing channels while simultaneously inducing a momentum-dependent phase twist in the triplet component. These results demonstrate that spin-selective dissipation provides a versatile non-Hermitian control knob for manipulating superfluid pairing, spectral structure, and crossover physics in spin-orbit-coupled quantum gases.

cond-mat.quant-gas↗

arXiv2026

Inversion-symmetric topological insulators in cut-and-project binary chains

We investigate the electronic properties of binary tight-binding chains generated by the cut-and-project method for rational slopes $α=p/q$, leading to periodic and inversion symmetric chains with $n=p+q$ sites. The binary structure is encoded in two hopping amplitudes $t_a$ and $t_b$. For fixed $t_a \neq t_b$, the support of the energy spectrum as a function of $p/n$ gives rise to a "Cut-and-Project butterfly". We concentrate on insulators with $M$ filled bands among a total of $n$ bands and vary $t_a/t_b$. Inversion symmetry constrains the electric polarization $P$ to $0$ or $P_q/2$ modulo a polarization quantum $P_q = \gcd(M,n)/n$. A topological transition, between two insulators that differ by their quantized polarization, occurs if and only if $n/\gcd(M,n)$ is odd. When $n/\gcd(M,n)$ is even, the two insulating regimes have a vanishing polarization and no topological transition occurs, despite the gap closing at $t_a=t_b$. When $n$ is even and $M$ odd, we find an adiabatic path between $t_a>t_b$ and $t_a<t_b$ that maintains inversion symmetry and a gap.

cond-mat.other↗

arXiv2026

Altermagnetism-Induced Spin-resolved electronic structure in Janus FeX0.5Y0.5 Monolayers (X, Y = S, Se, Te)

Realizing the spin-resolved electronic properties in superconducting materials stands as a critical frontier, offering both novel fundamental physics and potential for dissipationless spin-based devices. Here, we predict a series of Janus FeX0.5Y0.5 monolayers derived from iron-based superconductors (e.g., FeSe, FeTe, and FeS) by using Kondo-type model and first-principles calculations. These Janus structures exhibit significant spin-splittingelectronic states, large topological band gaps (51.4 meV) and high Néel temperatures (415 K). We further reveal that valley polarization can be effectively tuned via applied in-plane strain and the resulting valley-polarized anomalous Hall conductivity can be manipulated by shifting the Fermi level. Our work suggests a new strategy based on altermagnetism for engineering spin-splitting states in superconducting systems and inspires further exploration of superconducting spintronics.

cond-mat.mtrl-sci↗

arXiv2026

Stacking-Engineered Switchable Altermagnetism in Topological FeSe bilayer systems

Altermagnetism and topological insulators represent two of the most transformative frontiers in modern condensed matter physics, spintronics, and quantum information science. Bringing these two paradigms together opens a largely unexplored route toward fundamentally new quantum phenomena. Here, we predict a topological altermagnetic phase in bilayer tetragonal Fe-based superconductors and reveal it as a highly tunable platform for valley-polarized anomalous Hall physics. Based on first-principles calculations, we show that the characteristic spin-splitting and valley polarization can be effectively tuned via applied strain. Moreover, the resulting valley-polarized anomalous Hall conductivity can be manipulated by shifting the Fermi level. These findings reveal a powerful route for controlling altermagnetism in topological materials and identify a realistic material platform for its experimental realization and technological exploitation.

cond-mat.mtrl-sci↗

arXiv2026

TRUST-Planner: Topology-guided Robust Trajectory Planner for AAVs with Uncertain Obstacle Spatial-temporal Avoidance

Despite extensive developments in motion planning of autonomous aerial vehicles (AAVs), existing frameworks faces the challenges of local minima and deadlock in complex dynamic environments, leading to increased collision risks. To address these challenges, we present TRUST-Planner, a topology-guided hierarchical planning framework for robust spatial-temporal obstacle avoidance. In the frontend, a dynamic enhanced visible probabilistic roadmap (DEV-PRM) is proposed to rapidly explore topological paths for global guidance. The backend utilizes a uniform terminal-free minimum control polynomial (UTF-MINCO) and dynamic distance field (DDF) to enable efficient predictive obstacle avoidance and fast parallel computation. Furthermore, an incremental multi-branch trajectory management framework is introduced to enable spatio-temporal topological decision-making, while efficiently leveraging historical information to reduce replanning time. Simulation results show that TRUST-Planner outperforms baseline competitors, achieving a 96\% success rate and millisecond-level computation efficiency in tested complex environments. Real-world experiments further validate the feasibility and practicality of the proposed method.

cs.RO↗

arXiv2026

Heterogeneous AAV Logistics Task Allocation: A Reinforcement Learning Enhanced Overlapping Coalition Formation Game Approach

In dynamic urban logistics, the stochastic emergence of time-sensitive tasks poses a significant optimality challenge for heterogeneous AAVs logistics task allocation. To address this problem, a reinforcement learning enhanced overlapping coalition formation game approach is proposed. A dynamic task allocation model is established, where global optimality is mathematically quantified by a generalized logistics cost coupling service quality and resource consumption. To deal with the time-varying task sets induced by stochastic order arrivals, a transformer-based soft actor-critic network is designed. By leveraging multi-head self-attention to encode variable-length logistics states and capture task-wise spatiotemporal dependencies, the learned policy adaptively guides coalition updates, replacing heuristic rules in the overlapping coalition formation game. On this basis, heterogeneous AAVs can form more efficient overlapping coalitions for dynamic logistics tasks. The resulting coalition formation process is proven to constitute an exact potential game, which guarantees convergence to a Nash-stable equilibrium within a finite number of iterations. Numerical simulations demonstrate that the proposed algorithm effectively improves the optimality of task allocation under the generalized logistics cost criterion. In a scenario with 32 AAVs and 80 tasks, our algorithm achieves a 39.76% cost reduction compared with the heuristic OCF baseline. Indoor flight experiments further validate its practicality.

cs.RO↗

arXiv2026

Direct observation of quadruple spin-texture locking in a 2D d-wave altermagnet

Altermagnets combine vanishing net magnetization with nonrelativistic, momentum-dependent spin splitting, offering a new paradigm for spintronics. Spin-crystal symmetry coupling, namely spin-lattice locking, is the defining mechanism of altermagnetism, enforcing opposite spin sublattices in real space and spin-momentum-locked electronic structure in reciprocal space. Direct atomic-scale visualization of spin-lattice locking therefore constitutes a decisive benchmark of the altermagnetic state, yet such evidence has remained elusive despite extensive efforts. Here we show that the electronic states in RbV2Se2O exhibit a d-wave-like spin texture at the sublattice level, providing the first atomic-scale evidence of spin-lattice locking with a predominantly c-axis spin orientation. By employing an in-situ, field-switchable spin-polarized Cr tip, we realize spin-contrast mapping of quasiparticle interference at identical energies, overcoming a long-standing experimental barrier in altermagnets. The resulting interference patterns exhibit pronounced spin-dependent modulations, establishing spin scattering locking and spin momentum locking as the real and reciprocal space manifestations. Unexpectedly, we uncover that the spin-selective scattering response is organized by a long-period stripe modulation, giving rise to a previously unidentified form of spin-texture locking, spin-stripe locking. We attribute this behavior to the emergence of a spin-density-wave moiré pattern. Together, these results establish a unified picture of quadruple spin-texture locking phenomena in a d-wave altermagnet, and position altermagnets as a versatile platform for exploring many-body interactions among intertwined degrees of freedom, including spin, lattice, momentum, moiré potential and valley.

cond-mat.mtrl-sci↗

arXiv2026

High-Fidelity Universal Quantum Gate Compilation for Non-semisimple Ising Anyons via Genetic Algorithm-Optimized Solovay-Kitaev Decomposition

We present a systematic numerical construction of a universal quantum gate set for topological quantum computation based on the non-semisimple Ising anyons model. By employing a Genetic Algorithm-enhanced Solovay-Kitaev Algorithm (GA-enhanced SKA), we achieve high-fidelity approximations of standard single-qubit gates (Hadamard H-gate and phase T-gate) with a recursion level of just three, meeting the fidelity requirements for fault-tolerant quantum computation. Our numerical results demonstrate that for the critical parameter range α \in [2.001, 2.022], a few braiding operations can approximate the local equivalence class [CNOT] with high precision. Specifically, at α =2.012, 2.015, 2.020, and 2.022, we successfully construct a universal gate set {H, T, CNOT} with leakage errors of two-qubit gate below 0.07,0.08,0.09 and 0.10, respectively. This work establishes a new pathway towards universal quantum computation using non-semisimple Ising anyons, overcoming the limitations of traditional Ising models through optimized braiding sequences and Genetic Algorithm-driven compilation.

quant-ph↗

arXiv2026

Non-Hermitian topological superfluidity in a three-dimensional fermi gas with spin-orbit coupling

The experimental advances in realizing artificial spin-orbit coupling (SOC) and non-Hermitian potentials in ultracold atomic system open a new avenue for exploring their significant roles in quantum many-body physics. Here, we investigate a non-Hermitian, two-component Fermi system in a cubic lattice with Rashba SOC and complex-valued interaction arising from two-body loss. We adopt the non-Hermitian mean field theory and map out the phase diagram at zero temperature. The interplay of dissipation and on-site interaction drives a dissipation-induced phase transition from superfluid (SF) to normal phase (N). Notably, for weak interaction strengths, this leads to a reentrance of the superfluid state. The presence of SOC significantly expands the parameter regime for both the normal phase and the metastable superfluid phase(MSF). Whereas, the Zeeman field can drive the system from a conventional superfluid into a topological superfluid phase(TSF), characterized by a nontrivial topological invariant. These results enrich our knowledge of pairing superfluidity in Fermi systems.

cond-mat.quant-gas↗

arXiv2025

The construction of a universal quantum gate set for the SU(2)k (k=5,6,7) anyon models via genetic optimized algorithm

We study systematically numerical method into constructing a universal quantum gate set for topological quantum computation (TQC) using SU(2)k anyon models. The F-matrices and R-symbol were computed through the q-deformed representation theory of SU(2), enabling precise determination of elementary braiding matrices (EBMs) for SU(2)k anyon systems. Quantum gates were derived from these EBMs. One-qubit gates were synthesized using a genetic algorithm-enhanced Solovay-Kitaev algorithm (GA-enhanced SKA), while two-qubit gates were constructed through brute-force search or GA optimization to approximate local equivalence classes [CNOT]. Implementing this framework for SU(2)5, SU(2)6, and SU(2)7 models successfully generated the canonical universal gate set {H-gate, T-gate, CNOT-gate}. These numerical results provide conclusive verification of the universal quantum computation capabilities inherent in SU(2)k anyon models. Furthermore, we get exact implementations of the local equivalence class [SWAP] using nine EBMs in each model.

quant-ph↗

arXiv2025

Genetic algorithm enhanced Solovay-Kitaev algorithm for quantum compiling of Fibonacci anyons

Quantum compiling, which aims to approximate target qubit gates by finding optimal sequences (braidwords) of basic braid operations, constitutes a fundamental challenge in quantum computing. We develop a genetic algorithm (GA)-enhanced Solovay-Kitaev algorithm (SKA) for approximating single-qubit gates using four elementary braiding matrices (EBMs) derived from Fibonacci anyons. The GA-enhanced SKA demonstrates robust performance, efficiently identifying optimal braidwords within exponentially large search spaces. Notably, the approximation precision achieved by our method surpasses that of Monte Carlo (MC)-enhanced SKA and becomes comparable to deep reinforcement learning (RL) approaches when braidword lengths exceed 25. Implementing 2- and 3-order approximations with the GA-enhanced SKA yields optimal braidword (initial braiding lengths l0=50 and 30 respectively) achieving gate distances of 5.9*10-7 - sufficient precision for most quantum computing applications. This work develops an optimized compilation framework for non-Abelian anyon gates, providing an essential methodology for enhancing future topological quantum computation architectures through gate optimization.

quant-ph↗

arXiv2025

Long-Range Chiral Pairing enables Topological Superconductivity in Triangular Lattices without Spin-Orbit Coupling and Magnetic Field

This paper demonstrates a pathway to topological superconductivity in monolayer triangular lattices through long-range pairing without requiring spin-orbit coupling and magnetic field, contrasting conventional frameworks reliant on superconductivity and spin-orbit coupling and time-reversal symmetry (TRS) breaking. Berry curvature analysis reveals spontaneous TRS-breaking-induced peaks or valleys under long-range pairing, signaling nontrivial topology superconducting state. Notably, the increase in the long-range pairing strength only changes the size of the energy band-gap, without triggering a topological phase transition. This characteristic is verified by calculating Berry curvature and topological edge states. In zigzag and armchair-edge ribbons of finite width, the topological edge states are regulated by the ribbon boundary symmetry and the interact range of long-range pairing. Under nearest-neighbor pairing, the topological edge states maintain particle-hole symmetry and matches the corresponding Chern number. However, next-nearest-neighbor and third-nearest-neighbor pairings break the particle-hole symmetry of the topological edge states in armchair-edge ribbon. This work proposes a mechanism for realizing topological superconductivity without relying on spin-orbit coupling and magnetic field, offering a theoretical foundation for simplifying the design of topological quantum devices.

physics.comp-ph↗

arXiv2025

Surface band-selective moiré effect induces flat band in mixed-dimensional heterostructures

In this work, we reveal a curious type of moiré effect that selectively modifies the surface states of bulk crystal. We synthesize mixed-dimensional heterostructures consisting of a noble gas monolayer grow on the surface of bulk Bi(111), and determine the electronic structure of the heterostructures using angle-resolved photoemission spectroscopy. We directly observe moiré replicas of the Bi(111) surface states, while the bulk states remain barely changed. Meanwhile, we achieve control over the moiré period in the range of 25 Å to 80 Å by selecting monolayers of different noble gases and adjusting the annealing temperature. At large moiré periods, we observe hybridization between the surface band replicas, which leads to the formation of a correlated flat band. Our results serve as a bridge for understanding the moiré modulation effect from 2D to 3D systems, and provide a feasible approach for the realization of correlated phenomena through the engineering of surface states via moiré effects.

cond-mat.str-el↗

arXiv2025

Topological quantum compilation of metaplectic anyons based on the genetic optimized algorithms

Topological quantum computing holding global anti-interference ability is realized by braiding some anyons, such as well-known Fibonacci anyons. Here, based on $SO(3)_2 $ theory we obtain a total of 6 anyon models utilizing \textit{F}-matrices, \textit{R}-symbols, and fusion rules of metaplectic anyon.We obtain the elementary braiding matrices (EBMs) by means of unconventional encoding. After braiding \textit{X} and $X^\prime$, we insert a pair of \textit{Z} anyons into them to ensure that the initial order of anyons remains unchanged. In this process only fusion is required, and measurement is not necessary. Three of them $\{V^{113}_3,V^{131}_3,V^{133}_1\}$ are studied in detail. We study systematically the compilation of these three models through EBMs obtained analytically. For one-qubit case, the classical \textit{H}- and \textit{T}-gate can be well constructed using the genetic algorithm enhanced Solovay-Kitaev algorithm (GA-enhanced SKA) by $\{V^{113}_3,V^{131}_3,V^{133}_1\}$. The obtained accuracy of the \textit{H}/\textit{T}-gate by $\{V^{113}_3,V^{133}_1\}$ is slightly inferior to the corresponding gates of the Fibonacci anyon model, but it also can meet the requirements of fault-tolerant quantum computing, $V^{131}_3$ giving the best performance of these four models. For the two-qubit case, we use the exhaustive method for short lengths and the GA for long lengths to obtain braidword for $\{V^{113}_3,V^{131}_3,V^{133}_1\}$ models. The resulting matrices can well approximate the local equivalence class of the CNOT-gate, while demonstrating a much smaller error than the Fibonacci model, especially for the $V^{113}_3$.The braiding processes of conventional encoding (using identical anyons) and unconventional encoding (using distinct anyons) are compared. Finally, we attempt to generalize the model to the \textit{N}-qubit case.

quant-ph↗

arXiv2025

Natural and Intrinsic Vacancies in two-dimensional g-C$_3$N$_4$ for Trapping Isolated B and C Atoms as Color Centers

Color centers are vital for quantum information processing, but traditional ones often suffer from instability, difficulty in realization, and precise control of locations. In contrast, natural intrinsic vacancy-based color centers in two-dimensional systems offer enhanced stability and tunability. In this work, we demonstrate that g-C$_3$N$_4$ with natural intrinsic vacancies is highly suitable for trapping B/C atoms to form stable color centers as qubits. With easily identifiable vacancies, B/C atoms are expectable to be placed at the vacancy sites in g-C$_3$N$_4$ through STM manipulation. The vacancy sites are confirmed as the most stable adsorption positions, and once atoms are adsorbed, they are protected by diffusion barriers from thermal diffusions. The most stable charge states are C$_V^{+2}$/B$_V^{+2}$, C$_V^{+1}$/B$_V^{+1}$, and C$_V^0$/B$_V^0$ in turn, with charge transition levels of 0.39 eV and 2.49 eV, respectively. Specifically, the defect levels and net spin of C$_V$/B$_V$ can be adjusted by charge states. C$_V$, C$_V^{+1}$, C$_V^{+2}$, B$_V^{+1}$, and B$_V^{+2}$ exhibit optically allowable defect transition levels. The zero-phonon lines suggest fluorescence wavelengths fall within the mid-infrared band, ideal for qubit operations of stable initialization and readout. Furthermore, the Zero-field splitting (ZFS) parameter and the characteristic hyperfine tensor are provided as potential fingerprints for electron paramagnetic resonance (EPR) experiments.

cond-mat.mes-hall↗

arXiv2024

Mass Acquisition of Dirac Fermions in Bi4I4 by Spontaneous Symmetry Breaking

Massive Dirac fermions, which are essential for realizing novel topological phenomena, are expected to be generated from massless Dirac fermions by breaking the related symmetry, such as time-reversal symmetry (TRS) in topological insulators or crystal symmetry in topological crystalline insulators. Here, we report scanning tunneling microscopy and angle-resolved photoemission spectroscopy studies of α-Bi4I4, which reveals the realization of massive Dirac fermions in the (100) surface states without breaking the TRS. Combined with first-principle calculations, our experimental results indicate that the spontaneous symmetry breaking engenders two nondegenerate edges states at the opposite sides of monolayer Bi4I4 after the structural phase transition, imparting mass to the Dirac fermions after taking the interlayer coupling into account. Our results not only demonstrate the formation of the massive Dirac fermions by spontaneous symmetry breaking, but also imply the potential for the engineering of Dirac fermions for device applications.

cond-mat.mtrl-sci↗

arXiv2024

Isolated zero-energy flat-bands and intrinsic magnetism in carbon monolayers

Flat-band in twisted graphene bilayer has garnered widespread attention, and whether flat-bands can be realized in carbon monolayer is an interesting topic worth exploring in condensed matter physics. In this work, we demonstrate that, based on the theory of compact localized states, a series of two-dimensional carbon allotropes with flat-bands can be achieved. Two of them named as 191-8-66-C-r567x-1 and 191-10-90-C-r567x-1 are confirmed to be dynamically stable carbon phases with isolated or weakly overlapped flat-bands at the Fermi-level. The maximum Fermi velocities of the flat-band electrons are evaluated to be 1x10^4 m/s and 0.786x10^4 m/s, both of which are lower than the Fermi velocity of the flat-band electrons in magic-angle graphene (4x10^4 m/s). Furthermore, 191-8-66-C-r567x-1 has been confirmed to be a flat-band related magnetic half-metal with a magnetic moment of 1.854 miuB per cell, while 191-10-90-C-r567x-1 is a flat-band related magnetic normal metal with a magnetic moment of 1.663 miuB per cell. These results not only show that flat-bands can be constructed in carbon monolayer, but also indicate the potential for achieving metal-free magnetic materials with light elements based on flat-band theory.

cond-mat.mes-hall↗

arXiv2024

Switchable Ferroelectricity in Subnano Silicon Thin Films

Recent advancements underscore the critical need to develop ferroelectric materials compatible with silicon. We systematically explore possible ferroelectric silicon quantum films and discover a low-energy variant (hex-OR-2*2-P) with energy just 1 meV/atom above the ground state (hex-OR-2*2). Both hex-OR-2*2 and hex-OR-2*2-P are confirmed to be dynamically and mechanically stable semiconductors with indirect gaps of 1.323 eV and 1.311 eV, respectively. The ferroelectric hex-OR-2*2-P exhibits remarkable in-plane spontaneous polarization up to 120 Pc/m and is protected by a potential barrier (13.33 meV/atom) from spontaneously transitioning to hex-OR-22. To simulate the switching ferroelectricity in electric fields of the single-element silicon bilayer, we develop a method that simultaneously learns interatomic potentials and Born effective charges (BEC) in a single equivariant model with a physically informed loss. Our method demonstrates good performance on several ferroelectrics. Simulations of hex-OR-2*2-P silicon suggest a depolarization temperature of approximately 300 K and a coercive field of about 0.05 V/Å. These results indicate that silicon-based ferroelectric devices are feasible, and the ground state phase of the silicon bilayer (hex-OR-2*2) is an ideal system. Our findings highlight the promise of pure silicon ferroelectric materials for future experimental synthesis and applications in memory devices, sensors, and energy converters.

cond-mat.mtrl-sci↗