arXiv subjects

Timothy Zaklama

Publications and source records attributed to Timothy Zaklama.

8 recordsLinked to original sources

arXiv2026

Large Electron Model: A Universal Ground State Predictor

We introduce Large Electron Model, a single neural network model that produces variational wavefunctions of interacting electrons over the entire Hamiltonian parameter manifold. Our model employs the Fermi Sets architecture, a universal representation of many-body fermionic wavefunctions, which is further conditioned on Hamiltonian parameter and particle number. For interacting electrons in a two-dimensional harmonic potential, a single trained model accurately predicts the ground state wavefunction while generalizing across unseen coupling strengths and particle-number sectors, producing both accurate real-space charge densities and ground state energies, even up to $50$ particles. Our results establish a foundation model method for material discovery that is grounded in the variational principle, while accurately treating strong electron correlation beyond the capacity of density functional theory.

cond-mat.str-el↗

arXiv2025

Attention-Based Foundation Model for Quantum States

We present an attention-based foundation model architecture for learning and predicting quantum states across Hamiltonian parameters, system sizes, and physical systems. Using only basis configurations and physical parameters as inputs, our trained neural network is able to produce highly accurate ground state wavefunctions. For example, we build the phase diagram for the 2D square-lattice $t-V$ model with $N$ particles, from only 18 parameters $(V/t,N)$. Thus, our architecture provides a basis for building a universal foundation model for quantum matter.

cond-mat.str-el↗

arXiv2025

Non-monotonic band flattening near the magic angle of twisted bilayer MoTe$_2$

Twisted bilayer MoTe$_2$ (tMoTe$_2$) is an emergent platform for exploring exotic quantum phases driven by the interplay between nontrivial band topology and strong electron correlations. Direct experimental access to its momentum-resolved electronic structure is essential for uncovering the microscopic origins of the correlated topological phases therein. Here, we report angle-resolved photoemission spectroscopy (ARPES) measurements of tMoTe$_2$, revealing pronounced twist-angle-dependent band reconstruction shaped by orbital character, interlayer coupling, and moir\'e potential modulation. Density functional theory (DFT) captures the qualitative evolution, yet underestimates key energy scales across twist angles, highlighting the importance of electronic correlations. Notably, the hole effective mass at the K point exhibits a non-monotonic dependence on twist angle, peaking near 2{\deg}, consistent with band flattening at the magic angle predicted by continuum models. Via electrostatic gating and surface dosing, we further visualize the evolution of electronic structure versus doping, enabling direct observation of the conduction band minimum and confirm tMoTe$_2$ as a direct band gap semiconductor. These results establish a spectroscopic foundation for modeling and engineering emergent quantum phases in this moir\'e platform.

cond-mat.mes-hall↗

arXiv2025

Solving fractional electron states in twisted MoTe$_2$ with deep neural network

The emergence of moir\'e materials, such as twisted transition-metal dichalcogenides (TMDs), has created a fertile ground for discovering novel quantum phases of matter. However, solving many-electron problems in moir\'e systems presents significant challenges due to strong electron correlation and strong moir\'e band mixing. Recent advancements in neural quantum states hold the promise for accurate and unbiased variational solutions. Here, we introduce a powerful neural wavefunction to solve ground states of twisted MoTe2 across various fractional fillings, reaching unprecedented accuracy and system size. From the full structure factor and quantum weight, we conclude that our neural wavefunction accurately captures both the electron crystal at $\nu = 1/3$ and various fractional quantum liquids in a unified manner.

cond-mat.str-el↗

arXiv2025

Is attention all you need to solve the correlated electron problem?

The attention mechanism has transformed artificial intelligence research by its ability to learn relations between objects. In this work, we explore how a many-body wavefunction ansatz constructed from a large-parameter self-attention neural network can be used to solve the interacting electron problem in solids. By a systematic neural-network variational Monte Carlo study on a moir\'e quantum material, we demonstrate that the self-attention ansatz provides an accurate and efficient solution without human bias. Moreover, our numerical study finds that the required number of variational parameters scales roughly as $N^2$ with the number of electrons, which opens a path towards efficient large-scale simulations.

cond-mat.str-el↗

arXiv2024

Structure factor and topological bound of twisted bilayer semiconductors at fractional fillings

The structure factor is a useful observable for probing charge density correlations in real materials, and its long-wavelength behavior encapsulated by ``quantum weight'' has recently gained prominence in the study of quantum geometry and topological phases of matter. Here we employ the static structure factor, S(q), to explore the phase diagram of twisted transition metal dichalcogenides (TMDs), specifically tMoTe2, at filling factors n=1/3, 2/3 under varying displacement fields. Our results reveal a topological phase transition between a fractional Chern insulator (FCI) and a generalized Wigner crystal (GWC). This transition is marked by the appearance of Bragg peaks at charge-density-wave vectors, and simultaneously, large decrease of S(q) at small q which lowers the interaction energy. We further calculate the quantum weight of various FCI states, verifying the universal topological bound. Our findings provide new insights into the phase diagram of twisted TMDs and establish a general framework for characterizing topological phases through structure factor analysis.

cond-mat.str-el↗

arXiv2021

Energy spectrum and structure of one-dimensional few-electron Wigner crystals with and without coupling to light in cavity

Explicitly Correlated Gaussian basis is used to calculate the energies and wave functions of one dimensional few-electron systems in confinement potentials created by external potentials or coupling to light in cavity. The appearance and properties of Wigner crystal-like structures are discussed. It is shown that one dimensional Wigner crystals can be formed by coupling electrons to light due to the dipole self-interaction term in the light-matter Hamiltonian, provided an additional extremely weak confining potential is present.

quant-ph↗

arXiv2019

Simulation of a Hydrogen Atom in Laser Field Using the Time-Dependent Variational Principle

The time-dependent variational principle is used to optimize the linear and nonlinear parameters of Gaussian basis functions to solve the time-dependent Schrodinger equation in 1 and 3 dimensions for a one-body soft Coulomb potential in a laser field. The accuracy is tested comparing the solution to finite difference grid calculations using several examples. The approach is not limited to one particle systems and the example presented for two electrons demonstrates the potential to tackle larger systems using correlated basis functions.

quant-ph↗