1.7k citations · 5.7k across the 76 of their papers we have counts for
79 papers
Incoherent Spectral Weight Emerging from a Van Hove Singularity in a Kagome Metal
C. -y. Lim, J. Deng, A. Korshunov +14
Waterfall-like spectral features observed by angle-resolved photoemission spectroscopy (ARPES) are commonly associated with strong electronic correlations or electron-boson couplin…
Second-order coherence properties of ultrafast polariton dynamics in plasmonic lattices
Evgeny A. Mamonov, Lukas Freter, Sioneh Eyvazi +2
The first-order coherence properties of strongly coupled systems supporting polariton lasing and Bose-Einstein condensation (BEC) have been thoroughly studied and show consistent r…
Momentum Structure of Superconductivity and Sublattice Effects from Quasiparticle Interference in CsVSb
Aaron G. Greenberg, Xinze Yang, Junze Deng +11
Quantum interference encoded in the sublattice texture of kagome Bloch wavefunctions has been widely invoked as a route to correlated states, including chiral charge order, unconve…
Quantum geometry and critical temperature enhancement in MgB superconductivity
Yi Jiang, Haoyu Hu, Dumitru Călugăru +13
MgB, a phonon-mediated superconductor with record-high critical temperature K, is revisited to obtain a comprehensive theory of electrons, phonons, and their cou…
Superfluid weight in disordered flat-band superconductors as a competition between localization functionals
Kryštof Kolář, Tero T. Heikkilä, Päivi Törmä
According to Anderson's theorem, the gap of a time-reversal symmetric weak-coupling superconductor is unaffected by non-magnetic disorder. However, the superfluid weight (stiffness…
Theory of dynamical superradiance in organic materials
Lukas Freter, Piper Fowler-Wright, Javier Cuerda +3
We develop the theory of dynamical superradiance -- the collective exchange of energy between an ensemble of initially excited emitters and a single-mode cavity -- for organic mate…
T-matrix representation of optical scattering response: Suggestion for a data format
Nigar Asadova, Karim Achouri, Kristian Arjas +39
The transition matrix, frequently abbreviated as T-matrix, contains the complete information in a linear approximation of how a spatially localized object scatters an incident fiel…
Superfluid weight cross-over and critical temperature enhancement in singular flat bands
Guodong Jiang, Päivi Törmä, Yafis Barlas
Non-analytic Bloch eigenstates at isolated band degeneracy points exhibit singular behavior in the quantum metric. Here, a description of superfluid weight for zero-energy flat ban…
High topological charge lasing in quasicrystals
Kristian Arjas, Jani M. Taskinen, Rebecca Heilmann +2
Photonic modes exhibiting a polarization winding akin to a vortex possess an integer topological charge. Lasing with topological charge 1 or 2 can be realized in periodic lattices…
Flat-band ratio and quantum metric in the superconductivity of modified Lieb lattices
Reko P. S. Penttilä, Kukka-Emilia Huhtinen, Päivi Törmä
Flat bands may offer a route to high critical temperatures of superconductivity. It has been predicted that the quantum geometry of the bands as well as the ratio of the number of…
Essay: Where Can Quantum Geometry Lead Us?
Paivi Torma
Quantum geometry defines the phase and amplitude distances between quantum states. The phase distance is characterized by the Berry curvature and thus relates to topological phenom…
All-optical switching at the two-photon limit with interference-localized states
Ville A. J. Pyykkönen, Grazia Salerno, Jaakko Kähärä +1
We propose a single-photon-by-single-photon all-optical switch concept based on interference-localized states on lattices and their delocalization by interaction. In its 'open' ope…
Pseudospin-orbit coupling and non-Hermitian effects in the Quantum Geometric Tensor of a plasmonic lattice
Javier Cuerda, Jani M. Taskinen, Nicki Källman +2
We theoretically predict the full quantum geometric tensor, comprising the quantum metric and the Berry curvature, for a square lattice of plasmonic nanoparticles. The gold nanopar…
Observation of Quantum metric and non-Hermitian Berry curvature in a plasmonic lattice
Javier Cuerda, Jani M. Taskinen, Nicki Källman +2
We experimentally observe the quantum geometric tensor, namely the quantum metric and the Berry curvature, for a square lattice of radiatively coupled plasmonic nanoparticles. We o…
Suppression of non-equilibrium quasiparticle transport in flat band superconductors
Ville A. J. Pyykkönen, Sebastiano Peotta, Päivi Törmä
We study non-equilibrium transport through a superconducting flat-band lattice in a two-terminal setup with the Schwinger-Keldysh method. We find that quasiparticle transport is su…
Supefluidity of flat band Bose-Einstein condensates revisited
Aleksi Julku, Grazia Salerno, Päivi Törmä
We consider the superfluid weight, speed of sound and excitation fraction of a flat band Bose-Einstein condensate (BEC) within multiband Bogoliubov theory. The superfluid weight is…
Many-Body Superconductivity in Topological Flat Bands
Jonah Herzog-Arbeitman, Aaron Chew, Kukka-Emilia Huhtinen +2
In a flat band superconductor, bosonic excitations can disperse while unpaired electrons are immobile. To study this strongly interacting system, we construct a family of multi-ban…
Loss-driven topological transitions in lasing
Grazia Salerno, Rebecca Heilmann, Kristian Arjas +3
We experimentally observe lasing in a hexamer plasmonic lattice and find that when tuning the scale of the unit cell, the polarization winding of the emission changes. By a theoret…
Revisiting flat band superconductivity: dependence on minimal quantum metric and band touchings
Kukka-Emilia Huhtinen, Jonah Herzog-Arbeitman, Aaron Chew +2
A critical result in superconductivity is that flat bands, though dispersionless, can still host nonzero superfluid weight due to quantum geometry. We show that the derivation of t…
Orbital magnetization of Floquet topological systems
Gabriel E. Topp, Päivi Törmä, Dante M. Kennes +1
A general expression for the orbital magnetization of a Floquet system is derived. The expression holds for a clean system, and is valid for any driving protocol, and arbitrary occ…
Superfluidity and Quantum Geometry in Twisted Multilayer Systems
P. Törmä, S. Peotta, B. A. Bernevig
Designer 2D materials where the constituent layers are not aligned may result in band structures with dispersionless, "flat" bands. Twisted bilayer graphene has been found to show…
Spatial and Temporal Coherence in Strongly Coupled Plasmonic Bose-Einstein Condensates
Antti J. Moilanen, Konstantinos S. Daskalakis, Jani M. Taskinen +1
We report first-order spatial and temporal correlations in strongly coupled plasmonic Bose-Einstein condensates. The condensate is large, more than twenty times the spatial coheren…
Insulator-pseudogap crossover in the Lieb lattice
Kukka-Emilia Huhtinen, Päivi Törmä
We study the attractive Hubbard model in the Lieb lattice to understand the normal state above the superconducting critical temperature in a flat band system. We use cluster dynami…
Spin-Imbalanced Pairing and Fermi Surface Deformation in Flat Bands
Kukka-Emilia Huhtinen, Marek Tylutki, Pramod Kumar +3
We study the attractive Hubbard model with spin imbalance on two lattices featuring a flat band: the Lieb and kagome lattices. We present mean-field phase diagrams featuring exotic…