Inhomogeneous superfluids

We show examples of a striped superfluid in a simple $\lambda\varphi^4$ model at finite velocity and chemical potential with a global $U(1)$ or $U(2)$ symmetry. Whenever the chemical potential is large enough we find flowing homogeneous solutions and static inhomogeneous solutions at any arbitrary small velocity. For the $U(1)$ model the inhomogeneous solutions found are energetically favourable for large enough superfluid velocity and the homogeneous and inhomogeneous phases are connected via a first order phase transitions. On the other hand, the $U(2)$ model becomes striped as soon as we turn on the velocity through a second order phase transition. In both models increasing the velocity leads to a second order phase transition into a phase with no condensate.Comment: 14 pages, 6 figures, references adde

Hydrodynamic Modes of a holographic p−p- wave superfluid

In this work we analyze the hydrodynamics of a $p-$ wave superfluid on its strongly coupled regime by considering its holographic description. We obtain the poles of the retarded Green function through the computation of the quasi-normal modes of the dual AdS black hole background finding diffusive, pseudo-diffusive and sound modes. For the sound modes we compute the speed of sound and its attenuation as function of the temperature. For the diffusive and pseudo-diffusive modes we find that they acquire a non-zero real part at certain finite momentum.Comment: 16 pag., 6 fig. Reference added. Minor corrections. Version accepted for publication in JHE

Backreacting p-wave Superconductors

We study the gravitational backreaction of the non-abelian gauge field on the gravity dual to a 2+1 p-wave superconductor. We observe that as in the $p+ip$ system a second order phase transition exists between a superconducting and a normal state. Moreover, we conclude that, below the phase transition temperature $T_c$ the lowest free energy is achieved by the p-wave solution. In order to probe the solution, we compute the holographic entanglement entropy. For both $p$ and $p+ip$ systems the entanglement entropy satisfies an area law. For any given entangling surface, the p-wave superconductor has lower entanglement entropy.Comment: Minor Typos corrected, version published in JHE

The g-theorem and quantum information theory

We study boundary renormalization group flows between boundary conformal field theories in $1+1$ dimensions using methods of quantum information theory. We define an entropic $g$-function for theories with impurities in terms of the relative entanglement entropy, and we prove that this $g$-function decreases along boundary renormalization group flows. This entropic $g$-theorem is valid at zero temperature, and is independent from the $g$-theorem based on the thermal partition function. We also discuss the mutual information in boundary RG flows, and how it encodes the correlations between the impurity and bulk degrees of freedom. Our results provide a quantum-information understanding of (boundary) RG flow as increase of distinguishability between the UV fixed point and the theory along the RG flow.Comment: 34 pages + appendices, 8 figures. v2. Improved and corrected version of the proo

La dualidad gauge/gravedad y sus aplicaciones a la materia condensada

La presente tesis doctoral trata sobre recientes contribuciones en el contexto de super uidos holográ cos. Esto signi ca intentar preguntar y responder cuestiones relevantes acerca de super uidos fuertemente acoplados en el contexto de la conjetura de AdS/CFT. Siendo así, investigamos agujeros negros cargado y campos en un espacio asintóticamente AdS que consideramos buenos candidatos a duales gravitatorios de un super uido. Luego usando el diccionario holográ co vemos qué fenomenología obtenemos para los material que viven en el borde de AdS y esperamos que dicha fenomenología sea relevante. La tesis se organiza de la siguiente manera: Como toda tesis, comienza con una breve introducción al tema, donde se explican conceptos básicos de la conjetura de Maldacena y el Diccionario escrito por Gubser, Klebanov, Polyakov y Witten. Además en dicha introducción se habla sobre algunos de los desafíos actuales en el contexto de materia condensada y sobre cómo la holografía podría ayudar a superar algunos de estos desafíos. Luego se procede a narrar las contribuciones originales del autor al tema, que resumiremos a continuación. En el capítulo 2 se comenta el trabajo fundacional en el tema, por Hartnoll, Herzog y Horowitz para luego ir un paso más allá y estudiar el caso desordenado. El desorden se logra mediante considerando un potencial químico con una dependencia espacial aleatoria. Luego en el capítulo 3 se estudia la Entropía de entrelazamiento de un modelo con parámetro de orden vectorial. Extensión natural de estos dos modelos, imaginamos un super uido holográ co con simetría U(2), que nos acompañará desde el capítulo 4 en adelante. De este último modelo estudiaremos conductividades, modos quasinormales, y su comportamiento ante otras fuentes externas, como la velocidad o un segundo potencial químico.Facultad de Ciencias Exacta

Hydrodynamic modes of a holographic p−wave superfluid

In this work we analyze the hydrodynamics of a p− wave superfluid on its strongly coupled regime by considering its holographic description. We obtain the poles of the retarded Green function through the computation of the quasi-normal modes of the dual AdS black hole background finding diffusive, pseudo-diffusive and sound modes. For the sound modes we compute the speed of sound and its attenuation as function of the temperature. For the diffusive and pseudo-diffusive modes we find that they acquire a non-zero real part at certain finite momentum.Instituto de Física La Plat

Intermediate scalings for solv, nil, and SL2 (R) black branes

In this work, we will study black brane solutions that are not translationally invariant in the spatial directions along which it extends. Instead, we require homogeneity, which still allows points along the spatial directions to be related to each other by symmetries. We find Einstein-Maxwell-anti-de Sitter black hole solutions of which the near-horizon geometry corresponds to solv (Bianchi V1-1), nil (Bianchi II), or SL2(R) (Bianchi VIII). Interestingly, we observe that at intermediate temperatures our solutions have an scaling regime where different spacetime directions scale differently. We also compute the dc conductivities for these charged solutions and study how they scale in this intermediate regime.Fil: Arias, Raúl Eduardo. Scuola Internazionale Superiore Di Studi Avanzati; Italia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; ArgentinaFil: Landea, Ignacio Salazar. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Física La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Física La Plata; Argentin

The entropic gg-theorem in general spacetime dimension

We establish the irreversibility of renormalization group flows on a pointlike defect inserted in a $d$-dimensional Lorentzian conformal field theory. We identify the impurity entropy $g$ with the quantum relative entropy in two equivalent ways. One involves a null deformation of the Cauchy surface, and the other is given in terms of a local quench protocol. Positivity and monotonicity of the relative entropy imply that $g$ decreases monotonically along renormalization group flows, and provides a clear information-theoretic meaning for this irreversibility.Comment: v2: minor corrections, matches published version. 6 pages, 2 figure