Browsing by Author "Giamarchi, T."

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  • Dynamics of an impurity in a one-dimensional lattice
    (2013-04) Massel, F.; Kantian, A.; Daley, A.D.; Giamarchi, T.; Törmä, P.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    We study the non-equilibrium dynamics of an impurity in a harmonic trap that is kicked with a well-defined quasi-momentum, and interacts with a bath of free fermions or interacting bosons in a one-dimensional lattice configuration. Using numerical and analytical techniques we investigate the full dynamics beyond linear response, which allows us to quantitatively characterize states of the impurity in the bath for different parameter regimes. These vary from a tightly bound molecular state in a strongly interacting limit to a polaron (dressed impurity) and a free particle for weak interactions, with composite behaviour in the intermediate regime. These dynamics and different parameter regimes should be readily realizable in systems of cold atoms in optical lattices.
  • Excitations and impurity dynamics in a fermionic Mott insulator with nearest-neighbor interactions
    (2016-03-08) Visuri, A. M.; Giamarchi, T.; Törmä, Päivi
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    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 a one-dimensional lattice. The bath is in a Mott insulator state with alternating sites occupied and the impurity interacts with the bath by repulsive on-site interactions. We find that when the magnitudes of the on-site and nearest-neighbor interactions are close to each other, the system shows excitations of two qualitatively distinct types. For the first type, a domain wall and an antidomain wall of density propagate into opposite directions, while the impurity stays at the initial position. For the second one, the impurity is bound to the antidomain wall while the domain wall propagates, an excitation where the impurity and bath are closely coupled.
  • Impurity and soliton dynamics in a Fermi gas with nearest-neighbor interactions
    (2017-06-07) Visuri, A. M.; Törmä, P.; Giamarchi, T.
     A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
    We study spinless fermions with repulsive nearest-neighbor interactions perturbed by an impurity particle or a local potential quench. Using the numerical time-evolving block decimation method and a simplified analytic model, we show that the perturbations create a soliton-antisoliton pair. If solitons are already present in the bath, the two excitations have a drastically different dynamics: The antisoliton does not annihilate with the solitons and is therefore confined close to its origin while the soliton excitation propagates. We discuss the consequences for experiments with ultracold gases.