A5069409709- Physics of Superconductivity and Magnetism
- Advanced Condensed Matter Physics
- Theoretical and Computational Physics
- Iron-based superconductors research
- Quantum many-body systems
- Markov Chains and Monte Carlo Methods
- Topological Materials and Phenomena
- Complex Network Analysis Techniques
- Complex Systems and Time Series Analysis
- Quantum Chromodynamics and Particle Interactions
- Arctic and Antarctic ice dynamics
- Gaussian Processes and Bayesian Inference
- Fish Ecology and Management Studies
- 2D Materials and Applications
- Smart Grid Energy Management
- Climate change and permafrost
- Cryospheric studies and observations
- Marine animal studies overview
- Marine and fisheries research
- Magnetic and transport properties of perovskites and related materials
- Power Quality and Harmonics
- Geological and Geochemical Analysis
- Evolutionary Game Theory and Cooperation
- Advancements in Semiconductor Devices and Circuit Design
- Graphene research and applications
University of Bergen
2023-2024
The University of Tokyo
2018-2020
RIKEN Center for Emergent Matter Science
2014-2017
Norwegian University of Science and Technology
2013-2014
Recently, there have been extensive efforts to extend the physics of two-dimensional (2D) graphene three-dimensional (3D) semimetals with point/line nodes. Although it has known that certain crystalline symmetries play an important role in protecting band degeneracy, a general recipe for stabilizing especially presence spin-orbit coupling, is still lacking. Here, authors show class novel topological nodes can emerge off-centered rotation/mirror symmetry whose line/plane displaced from center...
We discuss the phase diagram and transitions in $U(1)\times \groupZ{2}$ three-band superconductors with broken time reversal symmetry. find that beyond mean field approximation for sufficiently strong frustration of interband interactions there appears an unusual metallic state precursory to a superconducting transition. In state, system is not superconducting. Nonetheless, it features spontaneously $\groupZ{2}$ By contrast, weak coupling energy domain wall between different states low thus...
Using Monte Carlo simulations, we explore the phase diagram and transitions in $\mathrm{U}(1)\ifmmode\times\else\texttimes\fi{}{\mathbb{Z}}_{2}$ $n$-band superconductors with spontaneously broken time-reversal symmetry (also termed $s+is$ superconductors), focusing on three-band case. In limit of infinite penetration length, system under consideration can, for a certain parameter regime, have single first-order transition from state to normal due nontrivial interplay between $\mathrm{U}(1)$...
In the field of frustrated magnetism, Kitaev models provide a unique framework to study phenomena spin fractionalization and emergent lattice gauge theories in two three spatial dimensions. Their ground states are quantum liquids, which can typically be described terms Majorana band structure an ordering underlying $\mathbb{Z}_2$ structure. Here we comprehensive classification "gauge physics" family elementary three-dimensional models, discussing how their thermodynamics state order depends...
Tracing internal reflection horizons (IRHs) in radio-echo sounding data is crucial for understanding ice sheet dynamics and reconstructing past climate conditions. We present an autoregressive generative model designed to trace IRHs iteratively, mimicking the human annotation process. Unlike conventional segmentation-based approaches, which require large training datasets yield one-shot predictions necessitating extensive post-processing (Moqadam et al. 2024), our works by estimating a...
We study the three-dimensional $SU(2)$-symmetric noncompact ${\text{CP}}^{1}$ model, with two charged matter fields coupled minimally to a Abelian gauge field. The phase diagram and nature of transitions in this model have attracted much interest after it was proposed describe an unusual continuous transition associated deconfinement spinons. Previously, has been demonstrated for various two-component theories that weakly first-order may appear as ones new universality class simulations...
Quantum spin ice, modeled for magnetic rare-earth pyrochlores, has attracted great interest hosting a U(1) quantum liquid, which involves spin-ice monopoles as gapped deconfined spinons, well gapless excitations analogous to photons. However, the global phase diagram under [111] field remains open. Here we uncover by means of unbiased Monte Carlo simulations that supersolid monopoles, showing both superfluidity and partial ionization, intervenes kagome ice fully ionized monopole insulator,...
We introduce \textit{Policy Guided Monte Carlo} (PGMC), a computational framework using reinforcement learning to improve Markov chain Carlo (MCMC) sampling. The methodology is generally applicable, unbiased and opens up new path automated discovery of efficient MCMC samplers. After developing general theory, we demonstrate some PGMC's prospects on an Ising model the kagome lattice, including when in its computationally challenging spin ice regime. Here, show that PGMC able automatically...
We investigate the magnetization processes of a standard Ginzburg-Landau model for chiral $p$-wave superconducting states in an applied magnetic field. find that phase diagram is dominated by triangular lattices doubly quantized vortices. Only close vicinity to upper critical field lattice starts dissociate into structure single-quanta The degeneracy between with opposite chirality broken nonzero If energetically unfavorable chirality, process inversion induced external results formation...
Abstract Otoliths are a central information source for fish ecology and stock management, conveying important data about age other life history individual fish. Traditionally, interpretation of otoliths has required skilled expert readers, but recently deep learning classification regression models have been trained to extract from images variety species. Despite high accuracy in many cases, the adoption such fisheries management slow. One reason may be that underlying mechanisms model uses...
We consider a lattice model of two complex scalar matter fields ${z}_{a},\phantom{\rule{0.16em}{0ex}}a=1,2$, under ${\mathbb{CP}}^{1}$ constraint $|{z}_{1}{|}^{2}+{|{z}_{2}|}^{2}=1$, minimally coupled to compact gauge field, with an additional Berry-phase term. This has been the origin large body works addressing novel paradigms for quantum criticality, in particular ``spin-quark'' (spinon) deconfinement $S=1/2$ antiferromagnets. map exactly onto link-current model, which permits use...
This paper discusses a doubly frustrated Kitaev model, in which not only the original spin degrees of freedom are subject to exchange frustration, but also emergent gauge freedom, exposed geometric frustration. Using sign-free quantum Monte Carlo simulations, it is shown that this frustration' leads suppression usual thermal ordering transition, and Majorana metal liquid ground state characterized by subtle interplay field fermions.
Chiral spin liquids (CSLs) are exceptional magnetic states that break time-reversal symmetry without long-range ordering. Here, the authors showcase a family of CSLs in three-dimensional extension Kitaev model on hypernonagon lattice, using quantum Monte Carlo simulations supplemented by variational calculations. Notably, all found to not only but concurrently also number lattice symmetries forming crystalline ordering underlying \ensuremath{\mathbb{Z}}${}_{2}$ gauge structure. It is further...
We study the effect of an externally imposed rotation or magnetic field on frustrated multiband superconductors and superfluids. The frustration originates with multiple superconducting bands crossing Fermi surface in conjunction interband Josephson couplings a positive sign. These tend to frustrate phases various components order parameter. This turn leads effective description terms $U(1)\ifmmode\times\else\texttimes\fi{}{Z}_{2}$-symmetric system, where essentially only $U(1)$ sector...
We compare the phase-diagrams of an effective theory a three-dimensional multi-band superconductor obtained within standard and cluster mean-field theories, in large-scale Monte Carlo simulations. In three dimensions, mean field fails locating correctly positions phase transitions, as well character transitions between different states. A calculations taking into account order-parameter fluctuations local environment improves results considerably for case extreme type-II superconductors...
We present a multihistogram reweighting technique for nonequilibrium Markov chains with discrete energies. The method generalizes the single-histogram of Yin et al. [Phys. Rev. E 72, 036122 (2005)], making it possible to calculate time evolution observables at posteriori chosen couplings based on set simulations performed other couplings. In same way as in an equilibrium setting improves practical range well use available data compared reweighting, advantages simulations. demonstrate...
We present a multihistogram reweighting technique for nonequilibrium Markov Chains with discrete energies. The method generalizes the single histogram of Yin et al. [Phys. Rev. E72, 036122 (2005)], making it possible to calculate time evolution observables at posteriori chosen couplings based on set simulations performed other couplings. In same way as in an equilibrium setting improves practical range well use available data compared reweighting, advantages simulations. demonstrate...