Persona:
Rodríguez Laguna, Javier

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0000-0003-2218-7980
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Rodríguez Laguna
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Javier
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2018 - 20192
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Autor: Santalla, Silvia N. × Fecha de finalización: 2019 ×

Resultados de la búsqueda

Mostrando 1 - 2 de 2
  • Miniatura
    Publicación
    Nonuniversality of front fluctuations for compact colonies of nonmotile bacteria
    (American Physical Society, 2018-07-10) Santalla, Silvia N.; Abad, José P.; Marín, Irma; Muñoz García, Javier; Vázquez, Luis; Cuerno, Rodolfo; Rodríguez Laguna, Javier; Espinosa Escudero, María del Mar
    The front of a compact bacterial colony growing on a Petri dish is a paradigmatic instance of non-equilibrium fluctuations in the celebrated Eden, or Kardar-Parisi-Zhang (KPZ), universality class. While in many experiments the scaling exponents crucially differ from the expected KPZ values, the source of this disagreement has remained poorly understood. We have performed growth experiments with B. subtilis 168 and E. coli ATCC 25922 under conditions leading to compact colonies in the classically alleged Eden regime, where individual motility is suppressed. Non-KPZ scaling is indeed observed for all accessible times, KPZ asymptotics being ruled out for our experiments due to the monotonic increase of front branching with time. Simulations of an effective model suggest the occurrence of transient nonuniversal scaling due to diffusive morphological instabilities, agreeing with expectations from detailed models of the relevant biological reaction-diffusion processes.
  • Miniatura
    Publicación
    Unusual area-law violation in random inhomogeneous systems
    (IOPScience, 2019-02-26) Alba, Vincenzo; Santalla, Silvia N.; Ruggiero, Paola; Calabrese, Pasquale; Sierra, Germán; Rodríguez Laguna, Javier
    The discovery of novel entanglement patterns in quantum manybody systems is a prominent research direction in contemporary physics. Here we provide the example of a spin chain with random and inhomogeneous couplings that in the ground state exhibits a very unusual area-law violation. In the clean limit, i.e. without disorder, the model is the rainbow chain and has volume law entanglement. We show that, in the presence of disorder, the entanglement entropy exhibits a power-law growth with the subsystem size, with an exponent 1/2. By employing the strong disorder renormalization group (SDRG) framework, we show that this exponent is related to the survival probability of certain random walks. The ground state of the model exhibits extended regions of short-range singlets (that we term ‘bubble’ regions) as well as rare long range singlet (‘rainbow’ regions). Crucially, while the probability of extended rainbow regions decays exponentially with their size, that of the bubble regions is power law. We provide strong numerical evidence for the correctness of SDRG results by exploiting the free-fermion solution of the model. Finally, we investigate the role of interactions by considering the random inhomogeneous XXZ spin chain. Within the SDRG framework and in the strong inhomogeneous limit, we show that the above area-law violation takes place only at the free-fermion point of phase diagram. This point divides two extended regions, which exhibit volume-law and area-law entanglement, respectively.