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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…
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…
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…
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…
Fast trimers in one-dimensional extended Fermi-Hubbard model
A. Dhar, P. Törmä, J. J. Kinnunen
We consider a one-dimensional two component extended Fermi-Hubbard model with nearest neighbor interactions and mass imbalance between the two species. We study the stability of tr…
Geometric origin of superfluidity in the Lieb lattice flat band
Aleksi Julku, Sebastiano Peotta, Tuomas Vanhala +2
The ground state and transport properties of the Lieb lattice flat band in the presence of an attractive Hubbard interaction are considered. It is shown that the superfluid weight…
Topological phase transitions in the repulsively interacting Haldane-Hubbard model
Tuomas I. Vanhala, Topi Siro, Long Liang +3
Using dynamical mean-field theory and exact diagonalization we study the phase diagram of the repulsive Haldane-Hubbard model, varying the interaction strength and the sublattice p…
Larkin-Ovchinnikov phases in two-dimensional square lattices
J. E. Baarsma, P. Törmä
We consider a two-component gas of fermions in optical lattices in the presence of a population imbalance within a mean-field theory. We study phase transitions from a normal gas o…
Excitations and impurity dynamics in a fermionic Mott insulator with nearest-neighbor interactions
A. -M. Visuri, T. Giamarchi, P. Törmä
We study analytically and with the numerical time-evolving block decimation method the dynamics of an impurity in a bath of spinless fermions with nearest-neighbor interactions in…
Superfluid phases of fermions with hybridized and orbitals
Shaoyu Yin, J. E. Baarsma, M. O. J. Heikkinen +2
We explore the superfluid phases of a two-component Fermi mixture with hybridized orbitals in optical lattices. We show that there exists a general mapping of this system to the Li…
Dynamical symmetry and pair tunneling in a one-dimensional Bose gas colliding with a mobile impurity
Elmer V. H. Doggen, Sebastiano Peotta, Päivi Törmä +1
Using the time-dependent density matrix renormalization group (TDMRG) we theoretically study the collision of a one-dimensional gas of interacting bosons with an impurity trapped i…
Condensation phenomena in plasmonics
J. -P. Martikainen, M. O. J. Heikkinen, P. Törmä
We study arrays of plasmonic nanoparticles combined with quantum emitters, quantum plasmonic lattices, as a platform for room temperature studies of quantum many-body physics. We o…
Superfluidity and Density Order in a Bilayer Extended Hubbard Model
Tuomas I. Vanhala, Jildou E. Baarsma, Miikka O. J. Heikkinen +3
We use cluster dynamical mean field theory to study the phase diagram of the square lattice bilayer Hubbard model with an interlayer interaction. The layers are populated by two-co…
Topological States with Broken Translational and Time-Reversal Symmetries in a Honeycomb-Triangular Lattice
R. Sarjonen, P. Törmä
We study fermions in a lattice, with on-site and nearest neighbor attractive interactions between two spin species. We consider two geometries: both spins in a triangular lattice,…
Non-local quantum fluctuations and fermionic superfluidity in the imbalanced attractive Hubbard model
M. O. J. Heikkinen, D. -H. Kim, M. Troyer +1
We study fermionic superfluidity in strongly anisotropic optical lattices with attractive interactions utilizing the cluster DMFT method, and focusing in particular on the role of…
One-dimensional Fermi polaron in a combined harmonic and periodic potential
Elmer V. H. Doggen, Anna Korolyuk, Päivi Törmä +1
We study an impurity in a one-dimensional potential consisting of a harmonic and a periodic part using both the time-evolving block decimation (TEBD) algorithm and a variational an…
Moving perturbation in a one-dimensional Fermi gas
A. -M. Visuri, D. -H. Kim, J. J. Kinnunen +2
We simulate a balanced attractively interacting two-component Fermi gas in a one-dimensional lattice perturbed with a moving potential well or barrier. Using the time-evolving bloc…
Fulde-Ferrell states and Berezinskii-Kosterlitz-Thouless phase transition in two-dimensional imbalanced Fermi gases
Shaoyu Yin, J. -P. Martikainen, P. Törmä
We study the superfluid properties of two-dimensional spin-population-imbalanced Fermi gases to explore the interplay between the Berezinskii-Kosterlitz-Thouless (BKT) phase transi…
Tunable critical supercurrent and spin-asymmetric Josephson effect in superlattices
Juha M. Kreula, Miikka O. J. Heikkinen, Francesco Massel +1
Combining the Josephson effect with magnetism, or spin dependence in general, creates novel physical phenomena. The spin-asymmetric Josephson effect is a predicted phenomenon where…
Collective excitations of a trapped Fermi gas at finite temperature
A. Korolyuk, J. J. Kinnunen, P. Törmä
We study collective excitations of a trapped Fermi gas at finite temperature using the Bogoliubov-deGennes mean-field theory in conjunction with the generalized random phase approx…
Finite temperature stability and dimensional crossover of exotic superfluidity in lattices
Miikka O. J. Heikkinen, Dong-Hee Kim, Päivi Törmä
We investigate exotic paired states of spin-imbalanced Fermi gases in anisotropic lattices, tuning the dimension between one and three. We calculate the finite temperature phase di…
Dynamics of an impurity in a one-dimensional lattice
Francesco Massel, Adrian Kantian, Andrew J. Daley +2
We study the non-equilibrium dynamics of an impurity in an harmonic trap that is kicked with a well-defined quasi-momentum, and interacts with a bath of free fermions or interactin…
Fulde-Ferrell--Larkin-Ovchinnikov state in the dimensional crossover between one- and three-dimensional lattices
Dong-Hee Kim, Päivi Törmä
We present a full phase diagram for the one-dimensional (1D) to three-dimensional (3D) crossover of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state in an attractive Hubbard model…
Expansion dynamics of the Fulde-Ferrell-Larkin-Ovchinnikov state
J. Kajala, F. Massel, P. Torma
We consider a two-component Fermi gas in the presence of spin imbalance, modeling the system in terms of a one-dimensional attractive Hubbard Hamiltonian initially in the presence…