Tootfinder

Cone-dependent retro and specular Andreev reflections in AA-stacked bilayer graphene
Wei-Tao Lu, Qing-Feng Sun
https://arxiv.org/abs/2509.04841 https://arx…

Cone-dependent retro and specular Andreev reflections in AA-stacked bilayer graphene
We theoretically study the Andreev reflection (AR) in AA-stacked bilayer graphene/superconductor (AABG/SC) junction. AABG has a linear gapless energy band with two shifted Dirac cones and the electronic states are described by the cone indices. The results indicate that the property of AR strongly depends on the cone degree of freedom. In the absence of the inter-layer potential difference, only intra-cone AR and normal reflection (NR) could occur, and the inter-cone process is forbidden. By ad…

On the $O(1/T)$ Convergence of Alternating Gradient Descent-Ascent in Bilinear Games
Tianlong Nan, Shuvomoy Das Gupta, Garud Iyengar, Christian Kroer
https://arxiv.org/abs/2510.03855

On the $O(1/T)$ Convergence of Alternating Gradient Descent-Ascent in Bilinear Games
We study the alternating gradient descent-ascent (AltGDA) algorithm in two-player zero-sum games. Alternating methods, where players take turns to update their strategies, have long been recognized as simple and practical approaches for learning in games, exhibiting much better numerical performance than their simultaneous counterparts. However, our theoretical understanding of alternating algorithms remains limited, and results are mostly restricted to the unconstrained setting. We show that f…

Double-pair Coulomb(-Breit) photon correction to the correlated relativistic energy
P\'eter Jeszenszki, Edit M\'atyus
https://arxiv.org/abs/2510.04571 https://

Double-pair Coulomb(-Breit) photon correction to the correlated relativistic energy
The simplest, algebraic quantum-electrodynamical corrections, due to the double-negative energy subspace and instantaneous interactions, are computed to the no-pair Dirac-Coulomb(-Breit) energy of two-spin-1/2-fermion systems. Numerical results are reported for two-electron atoms with a clamped nucleus and positronium-like genuine two-particle systems. The Bethe-Salpeter equation provides the theoretical framework, and numerical methods have been developed for its equal-time time-slice. In prac…

Coevolutionary Continuous Discrete Diffusion: Make Your Diffusion Language Model a Latent Reasoner
Cai Zhou, Chenxiao Yang, Yi Hu, Chenyu Wang, Chubin Zhang, Muhan Zhang, Lester Mackey, Tommi Jaakkola, Stephen Bates, Dinghuai Zhang
https://arxiv.org/abs/2510.03206

Coevolutionary Continuous Discrete Diffusion: Make Your Diffusion Language Model a Latent Reasoner
Diffusion language models, especially masked discrete diffusion models, have achieved great success recently. While there are some theoretical and primary empirical results showing the advantages of latent reasoning with looped transformers or continuous chain-of-thoughts, continuous diffusion models typically underperform their discrete counterparts. In this paper, we argue that diffusion language models do not necessarily need to be in the discrete space. In particular, we prove that continuo…

Strain Effects on Electronic Properties of Cobalt-Based Coordination Nanosheets
Kento Nishigomi, Yu Yi, Souren Adhikary, Kazuhito Tsukagoshi, Katsunori Wakabayashi
https://arxiv.org/abs/2510.03549

Strain Effects on Electronic Properties of Cobalt-Based Coordination Nanosheets
We theoretically study the strain effects on the electronic properties of cobalt-based benzenehexathiol (CoBHT) coordination nanosheets using first-principles calculations. Two distinct crystal structures, high-density structure (HDS) and low-density structure (LDS), are explored. Our results reveal that HDS behaves as a metal, while LDS exhibits semiconducting. Spin-polarized electronic band structures highlight the presence of energy band structures of Kagome lattice, and the incl…

Pointed Hopf algebras revisited, with a view from tensor categories
Iv\'an Angiono
https://arxiv.org/abs/2510.03124 https://arxiv.org/pdf/2510.03124

Pointed Hopf algebras revisited, with a view from tensor categories
Hopf algebras appear in connection with various problems in Pure Mathematics and Theoretical Physics, mainly through their categoriesof representations, which are examples of tensor categories. In recent years, there have been major advances in the classification of finite-dimensional Hopf algebras over the complex numbers, especially when restricted to the pointed case. In this survey, we aim to review the main results in this direction, stating the classification theorems recently obtained an…

Rectifying Regression in Reinforcement Learning
Alex Ayoub, David Szepesv\'ari, Alireza Baktiari, Csaba Szepesv\'ari, Dale Schuurmans
https://arxiv.org/abs/2510.00885 ht…

Rectifying Regression in Reinforcement Learning
This paper investigates the impact of the loss function in value-based methods for reinforcement learning through an analysis of underlying prediction objectives. We theoretically show that mean absolute error is a better prediction objective than the traditional mean squared error for controlling the learned policy's suboptimality gap. Furthermore, we present results that different loss functions are better aligned with these different regression objectives: binary and categorical cross-entrop…

Triple-Tone Microwave Control for Sensitivity Optimization in Compact Ensemble Nitrogen-Vacancy Magnetometers
Ankita Chakravarty, Romain Ruhlmann, Vincent Halde, David Roy-Guay, Michel Pioro-Ladri\`ere, Lilian Childress, Yves B\'erub\'e-Lauzi\`ere
https://arxiv.org/abs/2510.00913

Triple-Tone Microwave Control for Sensitivity Optimization in Compact Ensemble Nitrogen-Vacancy Magnetometers
Ensembles of nitrogen-vacancy (NV) centers in diamond are a well-established platform for quantum magnetometry under ambient conditions. One challenge arises from the hyperfine structure of the NV, which, for the common $^{14}$N isotope, results in a threefold reduction of contrast and thus sensitivity. By addressing each of the NV hyperfine transitions individually, triple-tone microwave (MW) control can mitigate this sensitivity loss. Here, we experimentally and theoretically investigate the …

Design of a Josephson diode based on double magnetic impurities
Yu-Fei Sun, Yue Mao, Qing-Feng Sun
https://arxiv.org/abs/2509.03984 https://arxiv.org/pdf/2…

Design of a Josephson diode based on double magnetic impurities
We theoretically propose a universal superconducting diode device based on double magnetic impurities which are coupled to the connection region of the Josephson junction. The positive and negative currents flowing across the junction can generate opposite magnetic fields, flipping the magnetic moment of the side magnetic impurity to the opposite directions, and in turn, the two impurities will have different impacts on the opposite currents. This results in the phenomenon that the positive and…

Quantum Effects or Theoretical Artifacts? A Computational Reanalysis of Hydrogen at High-Pressure
Stefano Racioppi, Eva Zurek
https://arxiv.org/abs/2510.02098 https://

Quantum Effects or Theoretical Artifacts? A Computational Reanalysis of Hydrogen at High-Pressure
The stability of high-pressure phases of hydrogen remains a central question in condensed matter physics, where both experimental observations and theoretical predictions are highly sensitive to methodological choices. Here, we revisit the cold phase diagram of hydrogen between 400 and 700 GPa using the meta-GGA functionals (R2SCAN and SCAN0) and compare the results with the more common PBE. At the meta-GGA level, molecular phases (Cmca-4, Cmca-12, and C2/c) are stabilized over the atomic I41/a…